CN102421734B - Method for producing denatured ethanol - Google Patents

Abstract

A process for producing a denatured ethanol composition, the process comprising the steps of: hydrogenating an acetic acid feed in the presence of a catalyst to form a caide ethanol product comprising ethanol and at least one denaturant, and separating the caide ethanol product in one or more separation units into a denatured ethanol composition and one or more derivative streams. The denatured ethanol composition comprises 0.01 wt.% to 40 wt.% of a denaturant, based on the total weight of the denatured ethanol composition.

Description

Method for producing denatured ethanol

priority claim

This application claims priority to: U.S. Provisional Application No. 61/300,815, filed February 2, 2010, U.S. Provisional Application No. 61/332,727, filed May 7, 2010, filed May 7, 2010 US Provisional Application No. 61/332,696; and US Application No. 12/889,260, filed September 23, 2010, which are hereby incorporated by reference in their entirety.

field of invention

The present invention relates generally to methods of producing denatured ethanol compositions, and more particularly to methods of producing denatured ethanol compositions by hydrogenation of acetic acid to form a crude ethanol product and a denaturant.

Background of the invention

The ethanol produced is commonly used as a component in a variety of consumer products such as beer, wine and spirit. Typically, ethanol intended for such uses is produced by fermentation. Many government agencies impose heavy taxes on consumer ethanol, raising costs for consumers.

However, there are many other uses of ethanol that do not involve consumption, such as fuel, chemical solvents or pharmaceuticals. As such, in an effort to provide cheap ethanol for non-consumer uses, the tax on consumer ethanol is typically not required for ethanol that is not intended for consumption. To ensure that such ethanol compositions are used in non-consumer applications, most countries have laws and regulations requiring these ethanol compositions to contain denaturants, which are added to otherwise substantially pure ethanol compositions to render the ethanol unsuitable for use in drink. Accordingly, ethanol compositions that contain denaturants and are not intended for consumption are often referred to as "denatured ethanol" or "denatured alcohol." Common denaturants include methanol, isopropanol, acetone, methyl ethyl ketone, ethyl acetate, methyl isobutyl ketone, and acetaldehyde.

The processing step of adding a denaturant to an otherwise potable ethanol composition adds complexity and cost to conventional denatured ethanol formation methods. Therefore, new and improved denatured ethanol formation methods are needed.

Summary of the invention

In a first embodiment, the present invention is directed to a method of producing a denatured ethanol composition comprising: hydrogenating acetic acid in the presence of a catalyst to form a crude ethanol product comprising ethanol and at least one denaturant; The crude ethanol product is separated in the unit into a denatured ethanol composition and one or more derivative streams, wherein the denatured ethanol composition, when formed, comprises from 0.01 wt.% to 40 wt.% based on the total weight of the denatured ethanol composition denaturant.

In a second embodiment, the present invention is directed to a method of producing a denatured ethanol composition comprising: hydrogenating acetic acid in the presence of a catalyst to form a caide ethanol product comprising ethanol and a denaturant; separating the caide ethanol product into an ethanol stream with at least one derived stream comprising the separated denaturant; further purifying the ethanol stream to form a purified ethanol stream; and combining at least a portion of the separated denaturant with the purified ethanol stream to produce a denatured ethanol composition.

Description of drawings

The present invention is described in detail below with reference to the accompanying drawings, in which like numerals designate like parts.

Figure 1A is a schematic diagram of a hydrogenation system according to one embodiment of the present invention.

Figure IB is a schematic diagram of the system shown in Figure IA in which the distillate from the second column is returned to the reactor zone.

Figure 1C is a schematic diagram of a hydrogenation system according to one embodiment of the invention.

Figure 2 is a graph showing the composition of an exemplary second residue stream at various tray locations within the third column.

Detailed description of the invention

Conventional denatured ethanol production methods begin with the production of purified ethanol. In these methods, ethanol can be formed and subsequently purified by conventional methods. A denaturant is then added to the purified ethanol to form denatured ethanol.

The present invention relates to methods of producing denatured ethanol compositions. In one embodiment, the invention is directed to a process comprising the step of hydrogenating acetic acid to form a caide ethanol product, eg, in the presence of a catalyst. The caide ethanol product comprises at least one, such as at least two or at least three denaturants. In one embodiment, a denaturant can be co-produced with ethanol. In another embodiment, the denaturant is formed as a by-product of the hydrogenation reaction. In other words, the denaturant is formed in situ along with the ethanol. In one embodiment, the method of the present invention further comprises separating the crude ethanol product into a denatured ethanol composition and one or more derivative streams. The separation may be performed in one or more, such as two or more, or three or more separation units (eg distillation columns). The resulting denatured ethanol composition as formed is derived from acetic acid and comprises 0.01 wt.% to 40 wt.%, such as 0.01 wt.% to 25 wt.%, 0.01 wt.% to 20 wt.%, based on the total weight of the denatured ethanol composition, or 1wt.%-15wt.% denaturant, and 50wt.%-99wt.%, such as 60wt.%-99wt.% or 70wt.%-95wt.% ethanol. Thus, by forming the denaturant in situ along with the ethanol during the hydrogenation step, the process of the present invention can produce denatured ethanol more efficiently and can reduce processing steps. In particular, the methods of the invention can eliminate the need to separately produce or obtain the denaturant and then add the denaturant to ethanol.

In another embodiment, the present invention is directed to a method of producing a denatured ethanol composition wherein the denaturant is formed by hydrogenation of acetone, which can be added to the reaction zone or formed in situ as an intermediate by-product of hydrogenation of acetic acid. In one aspect, for example, the method includes the step of contacting acetic acid with acetone to form an acetic acid reaction mixture. The process also includes hydrogenating the acetic acid reaction mixture in the presence of a catalyst to form a caide ethanol product comprising ethanol and isopropanol. In one embodiment, acetone is formed in an auxiliary acetone reactor or obtained from an external source. Once formed or obtained, acetone can be contacted with acetic acid as described above. In another aspect, the catalyst or reaction conditions used in the hydrogenation reaction are selected such that acetone is formed as a by-product of the acetic acid hydrogenation reaction. Once formed, the acetone intermediate can be hydrogenated to form isopropanol denaturant. In these embodiments, ethanol is co-produced with isopropanol denaturant. Preferably, ethanol and isopropanol are produced in the same reactor. In one embodiment, the method of the present invention further comprises separating the crude ethanol product into a denatured ethanol composition and one or more derivative streams. The resulting denatured ethanol composition, when formed, comprises 0.01 wt.% to 10 wt.%, such as 0.01 wt.% to 5 wt.%, or 0.01 wt.% to 3 wt.% isopropanol denatured based on the total weight of the denatured ethanol composition agent, and 50wt.%-99wt.%, such as 60wt.%-99wt.% or 70wt.%-95wt.% ethanol.

The hydrogenation of acetic acid to form ethanol and water can be represented by the following reaction:

Suitable hydrogenation catalysts include catalysts that optionally include a first metal and optionally include one or more of a second metal, a third metal, or an additional metal on a catalyst support. The first and optional second and third metals may be selected from: IB, HB, IIIB, IVB, VB, VIB, VIIB, VIII transition metals, lanthanides, actinides or from IIIA, IVA, VA and metals of any group in group VIA. Preferred metal combinations for some exemplary catalyst compositions include platinum/tin, platinum/ruthenium, platinum/rhenium, palladium/ruthenium, palladium/rhenium, cobalt/palladium, cobalt/platinum, cobalt/chromium, cobalt/ruthenium, Silver/palladium, copper/palladium, nickel/palladium, gold/palladium, ruthenium/rhenium and ruthenium/iron. Exemplary catalysts are also described in US Patent Nos. 7,608,744 and 7,863,489 and US Publication No. 2010/0197485, which are hereby incorporated by reference in their entirety.

In an exemplary embodiment, the catalyst comprises a first metal selected from the group consisting of copper, iron, cobalt, nickel, ruthenium, rhodium, palladium, osmium, iridium, platinum, titanium, zinc, chromium, rhenium, molybdenum, and tungsten. Preferably, the first metal is selected from platinum, palladium, cobalt, nickel and ruthenium. More preferably, the first metal is selected from platinum and palladium. When the first metal comprises platinum, the catalyst preferably comprises platinum in an amount of less than 5 wt.%, such as less than 3 wt.% or less than 1 wt.%, due to the high demand for platinum.

As indicated above, the catalyst optionally also includes a second metal, which can generally function as a promoter. If present, the second metal is preferably selected from copper, molybdenum, tin, chromium, iron, cobalt, vanadium, tungsten, palladium, platinum, lanthanum, cerium, manganese, ruthenium, rhenium, gold and nickel. More preferably, the second metal is selected from copper, tin, cobalt, rhenium and nickel. More preferably, the second metal is selected from tin and rhenium.

If the catalyst comprises two or more metals, such as a first metal and a second metal, the first metal is optionally present in an amount of 0.1 wt.% to 10 wt.%, such as 0.1 wt.% to 5 wt.% or 0.1 wt.%. An amount of -3 wt.% is present in the catalyst. The second metal is preferably present in an amount of 0.1 wt.% to 20 wt.%, such as 0.1 wt.% to 10 wt.% or 0.1 wt.% to 5 wt.%. For catalysts comprising two or more metals, the two or more metals may be alloyed with each other or may comprise non-alloyed metal solid solutions or mixtures.

The preferred metal ratios can vary depending on the metals used in the catalyst. In some exemplary embodiments, the molar ratio of the first metal to the second metal is preferably 10:1-1:10, such as 4:1-1:4, 2:1-1:2, 1.5:1-1 :1.5 or 1.1:1-1:1.1.

The catalyst may also comprise a third metal selected from any of the metals listed above with respect to the first or second metal, so long as the third metal is different from the first and second metals. In preferred aspects, the third metal is selected from cobalt, palladium, ruthenium, copper, zinc, platinum, tin and rhenium. More preferably, the third metal is selected from cobalt, palladium and ruthenium. When present, the total weight of the third metal is preferably from 0.05 wt.% to 4 wt.%, such as 0.1 to 3 wt.% or 0.1 wt.% to 2 wt.%.

Exemplary catalysts include, in addition to one or more metals, a support or a modified support, which refers to a support that includes a support material and a support modifier that adjusts the acidity of the support material. The total weight of the support or modified support is preferably 75 wt.% to 99.9 wt.%, such as 78 wt.% to 97 wt.% or 80 wt.% to 95 wt.%, based on the total weight of the catalyst. In a preferred embodiment using a modified support, the support modifier is based on the total weight of the catalyst at 0.1wt.%-50wt.%, such as 0.2wt.%-25wt.%, 0.5wt.%-15wt.% or 1wt .%-8 wt.% is present.

Suitable support materials may include, for example, stable metal oxide-based supports or ceramic-based supports. Preferred supports include siliceous supports such as silica, silica/alumina, Group IIA silicates such as calcium metasilicate, fumed silica, high purity silica, and mixtures thereof. Other supports may include, but are not limited to, iron oxides, alumina, titania, zirconia, magnesia, carbon, graphite, high surface area graphitized carbon, activated carbon, and mixtures thereof.

In the production of ethanol, catalyst supports can be modified with support modifiers. Preferably, the support modifier is a basic modifier with low or no volatility. Such basic modifiers may for example be selected from: (i) alkaline earth metal oxides, (ii) alkali metal oxides, (iii) alkaline earth metal metasilicates, (iv) alkali metal metasilicates, (v ) Group IIB metal oxides, (vi) Group IIB metal metasilicates, (vii) Group IIIB metal oxides, (viii) Group IIIB metal metasilicates, and mixtures thereof. In addition to oxides and metasilicates, other types of modifiers including nitrates, nitrites, acetates and lactates may be used. Preferably, the support modifier is selected from oxides and metasilicates of any element in sodium, potassium, magnesium, calcium, scandium, yttrium and zinc, and any mixture of the foregoing. Preferably, the support modifier is calcium silicate, more preferably calcium metasilicate (CaSiO ₃ ). If the support modifier comprises calcium metasilicate, at least a portion of the calcium metasilicate is preferably in crystalline form.

A preferred silica support material is SS61138 high surface area (HSA) silica catalyst support from Saint Gobain NorPro. Saint-Gobain NorProSS 61138 silica contains about 95 wt.% high surface area silica; surface area about 250 ^m2 /g; median pore diameter about 12 nm; average pore size of about 1.0 ^cm3 /g as measured by mercury intrusion porosimetry volume and bulk density of about 0.352 g/cm ³ (22 lb/ft ³ ).

A preferred silica/alumina support material is KA-160 (SudChemie) silica spheres having a nominal diameter of about 5 mm, a density of about 0.562 g/ml, an absorption of about 0.583 gH20/ _g support, Surface area of about 160-175 m ² /g and pore volume of about 0.68 ml/g.

Those skilled in the art will appreciate that the support material is selected such that the catalyst system has suitable activity, selectivity, and robustness under the process conditions used to produce ethanol.

The metal of the catalyst can be dispersed throughout the support, coated on the outer surface of the support (eggshell) or decorated on the support surface.

Catalyst compositions suitable for use in the present invention are preferably formed by metal impregnation of the modified support, although other methods such as chemical vapor deposition may also be used. Such impregnation techniques are described in US Patent Nos. 7,608,744 and 7,863,489 and US Publication No. 2010/0197485, which are hereby incorporated by reference in their entirety.

As will be readily appreciated by those skilled in the art, some embodiments of the method of hydrogenating acetic acid to form ethanol according to an embodiment of the present invention may include various configurations using fixed bed reactors or fluidized bed reactors. In many embodiments of the invention, "adiabatic" reactors may be used; that is, with little or no internal plumbing through the reaction zone to add or remove heat. In other embodiments, one reactor or multiple reactors with radial flow may be used, or a series of reactors with or without heat exchange, cooling, or introduction of additional feeds may be used. Alternatively, a shell and tube reactor equipped with a heat transfer medium can be used. In many cases, the reaction zone can be housed in a single vessel or in a series of vessels with heat exchangers in between.

In a preferred embodiment, the catalyst is used in a fixed bed reactor, eg in the shape of a tube or conduit, through which the reactants, typically in vapor form, are passed or passed. Other reactors may be used, such as fluidized bed or ebullating bed reactors. In some cases, hydrogenation catalysts may be used in conjunction with inert materials to regulate the pressure drop of the reactant stream through the catalyst bed and the contact time of the reactant compounds with the catalyst particles.

The hydrogenation reaction can be carried out in liquid or gas phase. Preferably, the reaction is carried out in the gas phase under the following conditions. The reaction temperature may be 125°C-350°C, such as 200°C-325°C, 225°C-300°C or 250°C-300°C. The pressure may be 10KPa-3000KPa (about 1.5-435psi), such as 50KPa-2300KPa or 100KPa-1500KPa. The reactants may be fed to the reactor at a gas hourly space velocity (GHSV) greater than 500 hr ⁻¹ , such as greater than 1000 hr ⁻¹ , greater than 2500 hr ⁻¹ , or even greater than 5000 hr ⁻¹ . In terms of ranges, the GHSV can be from 50 hr ⁻¹ to 50,000 hr ⁻¹ , such as 500 hr ⁻¹ to 30,000 hr ⁻¹ , 1000 hr ⁻¹ to 10,000 hr ⁻¹ , or 1000 hr ⁻¹ to 6500 hr ⁻¹ .

The hydrogenation is optionally carried out at the selected ^GHSV at a pressure just sufficient to overcome the pressure drop across the catalytic bed, although not limited to the use of higher pressures, it is understood that at high space velocities such as 5000 hr or 6,500 hr ^-1 may experience a considerable pressure drop across the reactor bed.

Although the reaction consumes 2 moles of hydrogen per mole of acetic acid to produce 1 mole of ethanol, the actual molar ratio of hydrogen to acetic acid in the feed stream can range from about 100:1 to 1:100, such as 50:1 to 1:50, 20: 1-1:2 or 12:1-1:1. Most preferably, the molar ratio of hydrogen to acetic acid is greater than 2:1, such as greater than 4:1 or greater than 8:1.

Contact or residence times can also vary widely, depending on variables such as the amount of acetic acid, catalyst, reactor, temperature and pressure. When using catalyst systems other than fixed beds, typical contact times range from fractions of a second to greater than several hours, at least for gas phase reactions, preferred contact times being 0.1-100 seconds, such as 0.3-80 seconds or 0.4-30 seconds Second.

The feedstocks, acetic acid and hydrogen used in connection with the methods of the present invention may be derived from any suitable source, including natural gas, petroleum, coal, biomass, and the like. As examples, acetic acid can be produced by methanol carbonylation, acetaldehyde oxidation, ethylene oxidation, oxidative fermentation, and anaerobic fermentation. As oil and gas prices fluctuate and become more or less expensive, methods for producing acetic acid and intermediates such as methanol and carbon monoxide from alternative carbon sources have gradually attracted attention. In particular, the production of acetic acid from synthesis gas ("syngas") derived from any available carbon source may become advantageous when petroleum is relatively expensive compared to natural gas. For example, US Patent No. 6,232,352, the disclosure of which is incorporated herein by reference, teaches a method of retrofitting a methanol plant to produce acetic acid. By retrofitting a methanol plant, the substantial capital costs associated with carbon monoxide production are significantly reduced or largely eliminated for new acetic acid plants. All or part of the synthesis gas is diverted from the methanol synthesis loop and fed to a separator unit to recover carbon monoxide and hydrogen, which are then used to produce acetic acid. In addition to acetic acid, this method can also be used to produce hydrogen which can be utilized in connection with the present invention.

Methanol carbonylation processes suitable for acetic acid production are described in U.S. Patent Nos. 7,208,624, 7,115,772, 7,005,541, 6,657,078, 6,627,770, 6,143,930, 5,599,976, 5,144,068, 5,026,908, 5,001,259, and 4,994,608, the disclosures of which are incorporated herein by reference. Optionally, ethanol production can be integrated with this methanol carbonylation process.

US Patent No. RE35,377 (also incorporated herein by reference) provides a method for producing methanol by converting carbonaceous materials such as oil, coal, natural gas, and biomass materials. The process includes hydrogasifying solid and/or liquid carbonaceous materials to obtain a process gas that is steam pyrolyzed with additional natural gas to form synthesis gas. This synthesis gas is converted to methanol which can be carbonylated to acetic acid. This process also produces hydrogen which can be used as described above in relation to the present invention. US Patent No. 5,821,111 and US Patent No. 6,685,754 disclose a method of converting waste biomass to syngas by gasification, the disclosures of which are incorporated herein by reference.

In an optional embodiment, the acetic acid feed stream to the hydrogenation reaction comprises acetic acid and may also comprise other carboxylic acids (eg propionic acid), esters and anhydrides, as well as acetaldehyde and acetone. In one embodiment, the acetic acid fed to the hydrogenation reaction comprises propionic acid. For example propionic acid in the acetic acid feed stream can be 0.001 wt.%-15 wt.%, such as 0.001 wt.%-0.11 wt.%, 0.125 wt.%-12.5 wt.%, 1.25 wt.%-11.25 or 3.75 wt. .%-8.75wt.%. Thus, the acetic acid feed stream may be a cruder acetic acid feed stream, such as a less refined acetic acid feed stream. In these embodiments, propionic acid in the acetic acid feed stream is hydrogenated to form n-propanol, which can act as a denaturant. N-propanol can be 0.001wt.%-15wt.%, such as 0.001wt.%-0.11wt.%, 0.13wt.%-13.2wt.%, 1.3wt.%-11.9wt.% or 4wt.%-9.3 An amount of wt.% is present in the denatured ethanol composition.

Alternatively, acetic acid in vapor form may be withdrawn directly as a crude product from the flasher of a methanol carbonylation unit of the type described in US Patent No. 6,657,078, which is hereby incorporated by reference in its entirety. For example, the crude vapor product can be fed directly to the ethanol synthesis reaction zone of the present invention without the need to condense acetic acid and light ends or remove water, thereby saving overall process costs.

In one embodiment, acetone is added as a reactant to the reactor in addition to acetic acid and hydrogen. Without being bound by theory, it is believed that adding acetone to the reaction produces isopropanol, which can act as a denaturant. On the other hand, acetone is formed as a by-product of the hydrogenation of acetic acid. Once formed, acetone can be hydrogenated to form isopropanol as a denaturant. In some embodiments, when isopropanol denaturant is desired, a separate catalyst can be used to produce higher concentrations of acetone, which upon subsequent hydrogenation can produce higher concentrations of isopropanol in the caide ethanol composition. propanol. As an example, catalyst compositions comprising supports such as TiO ₂ , ZrO ₂ , Fe ₂ O ₃ or CeO ₂ may be used. Other exemplary catalyst compositions include ruthenium on SiO ₂ , iron on carbon, or palladium on carbon.

In one embodiment, acetone is formed in an auxiliary reaction carried out in an auxiliary acetone reactor. As an example, acetic acid can be reacted in a secondary reactor under conditions effective to form acetone, such as ketolation. The acetic acid fed to the auxiliary reactor can be obtained from the acetic acid feed stream fed to the hydrogenation reactor. The auxiliary reactor can be of the type discussed above. For example, the auxiliary reactor may be a fixed bed reactor in which the catalyst is located. Preferably, the auxiliary reactor is in the shape of a tube or conduit wherein the reactants (typically in vapor form) pass through or through the catalyst located in the tube or conduit. In some embodiments, the auxiliary reactor utilizes a catalyst that promotes ketoylation and/or aids in the production of acetone. As an example, the catalyst may comprise a basic catalyst such as thorium oxide. In some embodiments, acetone produced in the auxiliary reactor is directed to the hydrogenation reactor as a reactant in addition to acetic acid and hydrogen.

Acetic acid can be vaporized at the reaction temperature, and the vaporized acetic acid can then be fed with hydrogen either undiluted or diluted with a relatively inert carrier gas such as nitrogen, argon, helium, carbon dioxide, and the like. To run the reaction in the gas phase, the temperature in the system should be controlled so that it does not drop below the dew point of the acetic acid. In one embodiment, acetic acid can be vaporized at a specific pressure at the boiling point of acetic acid, and then the vaporized acetic acid can be further heated to the reactor inlet temperature. In another embodiment, the acetic acid vapor is wetted by passing hydrogen, cycle gas, another suitable gas, or a mixture thereof through the acetic acid at a temperature below the boiling point of the acetic acid to convert the acetic acid to a vapor state. The carrier gas, followed by heating the mixed vapors up to the reactor inlet temperature. Preferably, the acetic acid is converted to vapor by passing hydrogen and/or recycle gas through the acetic acid at a temperature of or below 125°C, followed by heating the combined gaseous streams to the reactor inlet temperature.

In particular, hydrogenation of acetic acid can achieve favorable conversion of acetic acid and favorable selectivity and yield to ethanol. For the purposes of the present invention, the term "conversion" refers to the amount of acetic acid in the feed that is converted to compounds other than acetic acid. Conversions are expressed in mole percent based on acetic acid in the feed. The conversion may be at least 10%, such as at least 20%, at least 40%, at least 50%, at least 60%, at least 70%, or at least 80%. While catalysts with high conversions, such as at least 80% or at least 90%, are desirable, low conversions may be acceptable in some embodiments where ethanol selectivity is high. Of course, it is well understood that in many cases conversions can be made up by appropriate recycle streams or by using larger reactors, but poor selectivities are more difficult to make up for.

Selectivities are expressed in mole percent based on converted acetic acid. It is understood that each compound converted from acetic acid has an independent selectivity and that selectivity is independent of conversion. For example, if 50 mole percent of the converted acetic acid is converted to ethanol, then the ethanol selectivity is 50%. Preferably, the selectivity of the catalyst to ethoxylates is at least 60%, such as at least 70% or at least 80%. As used herein, the term "ethoxylate" specifically refers to the compounds ethanol, acetaldehyde and ethyl acetate. Preferably, the selectivity to ethanol is at least 80%, such as at least 85% or at least 88%. Preferred embodiments of this hydrogenation process also have low selectivity to undesired products such as methane, ethane and carbon dioxide. The selectivity to these undesired products is preferably less than 4%, such as less than 2% or less than 1%. More preferably, these undesired products are not detectable. The formation of alkanes can be low, ideally less than 2%, less than 1% or less than 0.5% of the acetic acid passing through the catalyst is converted to alkanes which have little value other than as fuel.

The term "productivity" as used herein refers to the grams of a defined product, such as ethanol, formed per hour during hydrogenation based on kilograms of catalyst used. Preferably the ethanol production rate is at least 200 grams per kilogram of catalyst per hour, such as at least 400 grams or at least 600 grams. In terms of ranges, the production rate is preferably 200-3,000 grams of ethanol per kilogram of catalyst per hour, such as 400-2,500 or 600-2,000.

In various embodiments, the crude ethanol product produced by the hydrogenation process will typically contain unreacted acetic acid, ethanol, and water prior to any subsequent processing, such as purification and isolation. As used herein, the term "caide ethanol product" refers to any composition comprising 5 wt.% to 70 wt.% ethanol and 5 wt.% to 35 wt.% water. In some exemplary embodiments, the caide ethanol product comprises ethanol in an amount of 5 wt.% to 70 wt.%, such as 10 wt.% to 60 wt.% or 15 wt.% to 50 wt.%, based on the total weight of the caide ethanol product. Preferably, the caide ethanol product comprises at least 10 wt.% ethanol, at least 15 wt.% ethanol, or at least 20 wt.% ethanol.

Depending on conversion, the caide ethanol product will typically also contain unreacted acetic acid, eg in an amount less than 90 wt.%, eg less than 80 wt.% or less than 70 wt.%. In terms of range, unreacted acetic acid is preferably 0wt.%-90wt.%, such as 5wt.%-80wt.%, 15wt.%-70wt.%, 20wt.%-70wt.% or 25wt.%-65wt. % amount present. When including acetone as a reactant, the crude ethanol product may contain 0.01 wt.%-10 wt.%, such as 0.1 wt.%-10 wt.%, 1 wt.%-9 wt.%, or 3 wt.%-7 wt.% isopropanol . In other embodiments, the caide ethanol product comprises 0.01 wt.% to 20 wt.%, such as 0.1 wt.% to 10 wt.%, 1 wt.% to 9 wt.%, or 3 wt.% to 7 wt.% diethyl ether. Since water is formed during the reaction, the caide ethanol product typically contains water in an amount of, for example, 5-35 wt.%, such as 10-30 wt.% or 10-26 wt.%. Ethyl acetate can also be produced during the hydrogenation of acetic acid or by side reactions. In these embodiments, the caide ethanol product comprises ethyl acetate in an amount of 0-20 wt.%, such as 0-15 wt.%, 1-12 wt.%, or 3-10 wt.%. Acetaldehyde can also be produced by side reactions. In these embodiments, the caide ethanol product comprises acetaldehyde in an amount of 0-10 wt.%, such as 0-3 wt.%, 0.1-3 wt.%, or 0.2-2 wt.%. In some embodiments wherein propionic acid is included as a reactant, n-propanol formed by hydrogenation may be present at 0.001 wt.% to 15 wt.%, such as 0.001 wt.% to 0.11 wt.%, 0.13 wt.% to 13.2 %, 1.3 wt.% - 11.9 wt.%, or 4 wt.% - 9.3 wt.% is present in the caide ethanol product.

Thus, the hydrogenation reaction produces a crude ethanol product that may include, inter alia, denaturants such as acetic acid, isopropanol, ethyl acetate, diethyl ether, acetaldehyde, and/or n-propanol. Each of these in situ formed compounds, alone or in combination with each other, can act as a denaturant in the denatured ethanol composition. In some embodiments, all or a portion of the crude ethanol product may be combined with a purified ethanol stream to form a denatured ethanol composition. It is within the scope of the present invention to adjust the reaction parameters to obtain the desired crude ethanol product and thus the desired denatured ethanol composition. In one embodiment, the amount of reactants such as acetic acid, acetone and/or propionic acid, etc., fed to the hydrogenation reactor can be adjusted to obtain a specific amount of one or more components in the crude ethanol product, e.g. denatured agent. The denaturant thus produced can be combined with the purified ethanol stream to form a denatured ethanol composition. For example, a denatured ethanol composition comprising about 5 parts isopropanol to 100 parts ethanol can be prepared by feeding an acetic acid stream comprising acetic acid and acetone. As another example, a denatured ethanol composition comprising about 5 parts n-propanol to 100 parts ethanol can be produced by feeding an acetic acid stream comprising acetic acid and propionic acid. It is also within the scope of this invention to adjust additional hydrogenation reactor parameters to obtain a caide ethanol product comprising a desired amount of a particular denaturant or combination of denaturants. For example, to produce a caide ethanol product containing about 10 parts diethyl ether, one can use co-pending U.S. application Ser. and disclosures incorporated herein) using a hydrogenation catalyst with an acidic support.

In one embodiment, because of the difficulty in separating isopropanol and ethanol from each other, all or part of the isopropanol formed in the hydrogenation reaction can follow ethanol through a separation scheme.

Because the caide ethanol composition may contain denaturant formed in situ as it is formed, at least a portion of the caide ethanol composition may be combined with the purified ethanol stream to form the denatured ethanol composition, with or without further separation. In one embodiment, one or more in situ formed denaturants may be separated from the crude ethanol product and combined with the purified ethanol stream. In other embodiments, at least a portion (eg, an aliquot) of the crude ethanol product can be combined with the purified ethanol stream. For example, when the caide ethanol product comprises n-propanol, at least a portion of the caide ethanol product comprising n-propanol can be combined with a purified ethanol stream to form a denatured ethanol composition comprising n-propanol denaturant. In another embodiment, at least a portion of the n-propanol is separated from the crude ethanol product and combined with the purified ethanol stream to form the n-propanol-denatured ethanol composition. As another example, when acetic acid is the desired denaturant, at least a portion of the crude ethanol composition comprising acetic acid can be combined with the purified ethanol stream to form a denatured ethanol composition comprising the acetic acid denaturant. In another embodiment, at least a portion of the acetic acid in the acetic acid feed and/or in any acetic acid recycle stream can be combined with the purified ethanol stream to form an acetic acid-denatured ethanol composition.

Other components such as esters, ethers, aldehydes, ketones, alkanes and carbon dioxide, if detectable, may together be present in an amount of less than 10 wt.%, such as less than 6 wt.% or less than 4 wt.%. In terms of ranges, the caide ethanol composition may comprise other components in an amount of 0.1 wt.% to 10 wt.%, such as 0.1 wt.% to 6 wt.% or 0.1 wt.% to 4 wt.%. Exemplary embodiments of crude ethanol composition ranges are provided in Table 1.

As shown in Table 1, in some embodiments, the caide ethanol product can be a denatured ethanol composition. For example, a caide ethanol composition may comprise ethanol and at least one denaturant such as acetic acid, ethyl acetate, or acetaldehyde. In other embodiments, the crude ethanol composition may be a denatured ethanol composition comprising at least one of the denaturants described above.

Figure 1A shows a hydrogenation system 100 suitable for hydrogenation of acetic acid and separation of ethanol from a crude reaction mixture, according to one embodiment of the invention. System 100 includes reaction zone 101 and distillation zone 102 . Reaction zone 101 comprises a reactor 103 , a hydrogen feed line 104 and an acetic acid feed line 105 . In other embodiments, when acetone is used as a reactant, reaction zone 101 also includes an acetone feed line (not shown). In other embodiments, when propionic acid is used as a reactant, reaction zone 101 also includes a propionic acid feed line (not shown). Distillation zone 102 comprises flasher 106 , first column 107 , second column 108 and third column 109 . Hydrogen, acetic acid, and optionally acetone and/or propionic acid are fed to vaporizer 110 via lines 104 and 105 to produce a vapor feed stream in line 111 leading to reactor 103 . In one embodiment, lines 104 and 105 can be combined and co-fed to vaporizer 110, for example, in one stream comprising hydrogen and acetic acid. The temperature of the vapor feed stream in line 111 is preferably from 100°C to 350°C, eg, from 120°C to 310°C or from 150°C to 300°C. As shown in FIG. 1A , any feed that is not vaporized is removed from vaporizer 110 and may be recycled thereto. Furthermore, while FIG. 1A shows line 111 leading to the top of reactor 103 , line 111 may lead to the side, top, or bottom of reactor 103 . Although one reactor and one flasher are shown in Figures 1A, 1B and 1C, additional reactors and/or components may be included in various alternative embodiments of the invention. For example, the hydrogenation system may optionally contain dual reactors, dual flashers, heat exchangers, and/or preheaters.

Reactor 103 contains a catalyst for hydrogenating a carboxylic acid, preferably acetic acid. In some embodiments where acetone is the reactant and isopropanol is the desired co-product along with ethanol, the catalyst in reactor 103 is selected such that isopropanol is produced in addition to ethanol. As an example, catalyst compositions comprising supports such as TiO ₂ , ZrO ₂ , Fe ₂ O ₃ or CeO ₂ may be used. In some embodiments, these catalysts promote higher acetone formation. Other exemplary catalyst compositions include ruthenium on SiO ₂ , iron on carbon, or palladium on carbon. In other embodiments, the temperature of reactor 103 can be adjusted to obtain a desired concentration of isopropanol. For example, maintaining the reaction temperature at 200°C-350°C, such as in the range of 225°C-300°C, can produce 0.1wt.%-10wt.%, such as 1wt.%-9wt.% or 3wt.%-7wt. Ethanol composition of % isopropanol. In one embodiment, one or more guard beds (not shown) may be used to protect the catalyst from toxics or undesired impurities contained in the feed or return/recycle streams. Such guard beds can be used in vapor or liquid streams. Suitable guard bed materials are known in the art and include, for example, carbon, silica, alumina, ceramics or resins. In one aspect, the guard bed media is functionalized to trap specific species such as sulfur or halogens. A caide ethanol product stream is preferably withdrawn continuously from reactor 103 via line 112 during the hydrogenation process. The caide ethanol product stream can be condensed and fed to flasher 106, which in turn provides a vapor stream and a liquid stream. In one embodiment, flasher 106 preferably operates at a temperature of 50°C to 500°C, eg, 70°C to 400°C or 100°C to 350°C. In one embodiment, the pressure of the flasher 106 is preferably 50KPa-2000KPa, such as 75KPa-1500KPa or 100-1000KPa. In a preferred embodiment, the temperature and pressure of the flasher are similar to those of reactor 103.

The vapor stream exiting flasher 106 may contain hydrogen and hydrocarbons, which may be purged and/or returned to reaction zone 101 via line 113 . As shown in FIG. 1A , the return portion of the vapor stream passes through compressor 114 and is combined with the hydrogen feed, co-fed to vaporizer 110 .

Liquid from flasher 106 is withdrawn and pumped as a feed composition through line 115 to the side of first column 107 (also referred to as an acid separation column). The contents of line 115 will typically be substantially similar to the product obtained directly from the reactor, and indeed may also be referred to as the caide ethanol product. However, the feed composition in line 115 is preferably substantially free of hydrogen, carbon dioxide, methane or ethane, which are removed via flasher 106 . Exemplary compositions of the liquid in line 115 are provided in Table 2. It should be understood that liquid line 115 may contain other components (not listed) such as those in the feed.

Throughout the tables of this application less than (<) indicated amounts are preferably absent and if present may be present in trace amounts or in amounts greater than 0.0001 wt.%.

"Other esters" in Table 2 may include, but are not limited to, ethyl propionate, methyl acetate, isopropyl acetate, n-propyl acetate, n-butyl acetate, or mixtures thereof. "Other ethers" in Table 2 may include, but not limited to, diethyl ether, methyl ethyl ether, isobutyl ethyl ether, or mixtures thereof. "Other alcohols" in Table 2 may include, but are not limited to, methanol, isopropanol, n-propanol, n-butanol, or mixtures thereof. In one embodiment, a feed composition such as line 115 may advantageously comprise a small amount of, for example, 0.001 wt. Alcohols such as isopropanol and/or n-propanol. Due to these low concentrations of alcohols, the resulting denatured ethanol composition advantageously contains only traces, if any, of said alcohols (see discussion below). These traces are significantly lower than those obtained by processes that do not use acetic acid hydrogenation. In other embodiments, the concentration of isopropanol in the feed composition is higher, eg, 0.01-10 wt.%. In other embodiments, the concentration of n-propanol in the feed composition is higher, eg, 0.01-10 wt.%. In other embodiments, the concentration of diethyl ether in the feed composition is higher, eg, 0.01-20 wt.%. It should be understood that these other components may be carried over in any of the distillate or residue streams described herein. In addition, as indicated above, some of these other components, such as isopropanol or diethyl ether, can also be used as denaturants.

When the content of acetic acid in line 115 is less than 5 wt.%, acid separation column 107 can be skipped and line 115 can be introduced directly to second column 108 (also referred to herein as light ends column).

In the embodiment shown in FIG. 1A , line 115 is introduced into the lower portion of first column 107 , eg, the lower half or third. In first column 107, unreacted acetic acid, some of the water, and other heavies, if present, are removed from the composition in line 115 and preferably continuously as a residue. Some or all of the residue may be returned and/or recycled back to reaction zone 101 via line 116 . The first column 107 also forms an overhead, which is withdrawn in line 117 and which can be split, for example, in a ratio of 10:1-1:10, such as 3:1-1:3 or 1:2-2: 1 ratio condensation and reflux.

Any of columns 107, 108 or 109 may comprise any distillation column capable of separation and/or purification. The column preferably comprises a tray column having 1-150 trays, eg 10-100 trays, 20-95 trays or 30-75 trays. The trays may be sieve trays, fixed valve trays, moving valve trays, or any other suitable design known in the art. In other embodiments, packed columns may be used. For packed columns, structured packing or random packing can be used. The columns or packing can be arranged in a continuous column or they can be arranged in two or more columns so that the vapor from the first stage enters the second stage while the liquid from the second stage enters the second stage. For a while, wait.

The associated condensers and liquid separation vessels that may be used with each distillation column may be of any conventional design and are simplified in Figures 1A, 1B and 1C. As shown in Figures 1A, 1B and 1C, heat can be supplied to the bottom of each column or to a circulating bottoms stream through a heat exchanger or reboiler. In some embodiments, other types of reboilers, such as internal reboilers, may also be used. The heat provided to the reboiler may be derived from any heat generated during a process integrated with the reboiler or from an external source such as another chemical process or boiler that produces heat. Although one reactor and one flasher are shown in Figures 1A, IB and 1C, additional reactors, flashers, condensers, heating elements and other components may be used in embodiments of the invention. As can be appreciated by those skilled in the art, various condensers, pumps, compressors, reboilers, drums, valves, connectors, separation vessels, etc. commonly used in conducting chemical processes can also be combined and used in the method of the present invention.

The temperatures and pressures used in any column can vary. As a practical matter, pressures from 10 KPa to 3000 KPa may generally be used in these regions, although in some embodiments subatmospheric pressures as well as superatmospheric pressures may be used. The temperature in each zone will generally be in the range between the boiling point of the composition removed as distillate and the composition removed as residue. Those skilled in the art will recognize that the temperature at a given location in an operating distillation column depends on the composition of the feed at that location and the pressure of the column. Furthermore, feed rates may vary depending on the scale of the production process and, if described, may generally refer to feed weight ratios.

When column 107 is operated at normal atmospheric pressure, the temperature of the residue exiting column 107 in line 116 is preferably from 95°C to 120°C, eg 105°C to 117°C or 110°C to 115°C. The temperature of the distillate exiting column 107 in line 117 is preferably from 70°C to 110°C, eg, from 75°C to 95°C or from 80°C to 90°C. In other embodiments, the pressure of the first column 107 may be 0.1KPa-510KPa, such as 1KPa-475KPa or 1KPa-375KPa. Exemplary components of the distillate and residue compositions of first column 107 are provided in Table 3 below. It should also be understood that the distillates and residues may also contain other components not listed, such as components in the feed. For convenience, the distillate and residue of the first column may also be referred to as "first distillate" or "first residue". Distillates or residues from other columns may also be referred to with similar numerical modifiers (second, third, etc.) in order to distinguish them from each other, but such modifiers should not be construed as requiring any particular order of separation .

As shown in Table 3, while not being bound by theory, it has been surprisingly and unexpectedly discovered that when any amount of acetal is detected in the feed to the acid separation column (first column 107), the acetal appears to be present in the The decomposition in this column is such that little or even no detectable amount is present in the distillate and/or residue.

Depending on the reaction conditions, the caide ethanol product exiting reactor 103 in line 112 may comprise ethanol, acetic acid (unconverted), ethyl acetate, and water. After exiting reactor 103, the caide ethanol product may undergo a non-catalyzed equilibrium reaction between the components contained therein before being fed to flasher 106 and/or first column 107. As shown below, this equilibrium reaction tends to drive the crude ethanol product to an equilibrium between ethanol/acetic acid and ethyl acetate/water.

Extended residence times may be encountered where the crude ethanol product is temporarily stored, eg, in storage tanks, before being directed to distillation zone 102 . In general, the longer the residence time between reaction zone 101 and distillation zone 102, the more ethyl acetate is formed. For example, when the residence time between reaction zone 101 and distillation zone 102 is greater than 5 days, significantly more ethyl acetate is formed at the loss of ethanol. Accordingly, shorter residence times between reaction zone 101 and distillation zone 102 are generally preferred to maximize the amount of ethanol formed. In one embodiment, a storage tank (not shown) is included between reaction zone 101 and distillation zone 102 for temporary storage of liquid components from line 115 for up to 5 days, eg up to 1 day or up to 1 hour. In a preferred embodiment, a tank is not included and the condensed liquid is fed directly to the first distillation column 107 . Additionally, the rate at which the non-catalyzed reaction proceeds can increase as the temperature of the caide ethanol product in line 115, for example, increases. These reaction rates can be particularly problematic at temperatures above 30°C, such as above 40°C or above 50°C. Thus, in one embodiment, the temperature of the liquid component in line 115 or in an optional storage tank is maintained at a temperature of less than 40°C, eg, less than 30°C or less than 20°C. One or more cooling devices may be used to reduce the temperature of the liquid in line 115.

As discussed above, a storage tank (not shown) may be included between reaction zone 101 and distillation zone 102 for temporary storage of the liquid component from line 115, for example, for 1-24 hours, optionally at a temperature of about 21°C, and corresponding to 0.01 wt.%-1.0 wt.% ethyl acetate formation, respectively. Additionally, the rate at which non-catalyzed reactions proceed can increase as the temperature of the caide ethanol product increases. For example, as the temperature of the caide ethanol product in line 115 increases from 4°C to 21°C, the rate of ethyl acetate formation can increase from about 0.01 wt.%/hour to about 0.005 wt.%/hour. Thus, in one embodiment, the temperature of the liquid component in line 115 or in an optional storage tank is maintained at a temperature of less than 21°C, eg, less than 4°C or less than -10°C.

Furthermore, it has been found that the above-mentioned equilibrium reaction can also promote the formation of ethanol in the top region of the first column 107 .

As shown in Figures 1A-C, the distillate from column 107, eg, the overhead stream, is optionally condensed and refluxed, preferably at a reflux ratio of 1:5 to 10:1. The distillate in line 117 preferably contains ethanol; in situ denaturants such as ethyl acetate and/or acetaldehyde; water, and other impurities that can be difficult to separate due to the formation of binary and ternary azeotropes. The first distillate also contained significantly reduced amounts of acetic acid. As shown in Figure 1C, in some embodiments, the distillate from the first column (without further treatment) is 0.0001wt.%-80wt.%, such as 0.001wt.%-60wt.% denaturant, and 20wt Denatured ethanol composition of .%-75wt.%, such as 30wt.%-70wt.% ethanol. Preferably, the denaturant in these embodiments is ethyl acetate. In other embodiments, the distillate from the first column (without further treatment) comprises 0.0001 wt.% to 10 wt.%, such as 0.001 wt.% to 5 wt.% or 0.01 wt.% to 4 wt.% denaturant, And denatured ethanol compositions of 20wt.%-75wt%, such as 30wt.%-70wt.% ethanol. Preferably, the denaturant in these embodiments is acetaldehyde.

In another embodiment, at least a portion of the first distillate can be combined with the purified ethanol stream via optional line 117' to form a denatured ethanol composition. Preferably, the denaturant comprises ethyl acetate and/or acetaldehyde. In another embodiment, at least a portion of the first distillate may be fed to an additional column, such as a third column as discussed below. As a result, denaturants, such as ethyl acetate and/or acetaldehyde, in the first distillate can be carried over to the distillate from the third column. As such, the third distillate may be a denatured ethanol composition comprising the denaturant from the first distillate. In these embodiments, the weight percent of denaturant in the denatured ethanol composition can be as previously discussed. The weight ratio of the denaturant-containing stream, such as line 117, to the purified ethanol stream varies widely and can be adjusted to obtain a particular desired concentration of denaturant in the denatured ethanol composition. For example, the weight ratio of the purified ethanol stream to the denaturant-containing stream may be from 0.01:1 to 5:1, such as from 0.05:1 to 3:1.

As discussed above, the residue from first column 107 contains some amount of unreacted acetic acid. Thus, in another embodiment, at least a portion of the first residue can be combined with the purified ethanol stream to form an acetic acid-denatured ethanol composition.

Advantageously, these denatured ethanol compositions are produced using denaturants formed in situ by hydrogenation reactions and without additional separation steps. As such, it is not necessary to provide an additional external source of denaturant or combine the denaturant with purified ethanol, which cuts down process steps and simplifies the overall process. It is also within the scope of the invention to further purify the first column distillate to remove, for example, additional water and/or acetaldehyde. Such additional purification can be achieved using conventional separation methods.

As shown in Table 3, the first residue contains a significant portion of unreacted acetic acid, which can in turn be recycled back to reactor 103 as shown in Figures 1A, 1B and 1C.

The first distillate in line 117 is introduced to second column 108 (also referred to as "light ends column"), preferably in the middle portion of column 108, such as the middle half or middle third. The second column 108 may be a tray column or a packed column. In one embodiment, the second column 108 is a tray column having 5-70 trays, such as 15-50 trays or 20-45 trays.

As an example, when using a 25-tray column in a column without water extraction, line 117 is introduced at tray 17. When the second column is not an extractive distillation column, it is expected that ethyl acetate in line 117 can be separated along with ethanol and water into a second residue. As a result, in one embodiment, more ethyl acetate may be fed to third column 109, and thus, this ethyl acetate may be present in the third distillate. In other embodiments, at least a portion of the ethyl acetate-containing second residue can be combined with the purified ethanol stream to form a denatured ethanol composition.

However, in a preferred embodiment, second column 108 may be an extractive distillation column. In the extractive distillation column, it is expected that the ethyl acetate in line 117 can be separated from the ethanol and water and passed into the second distillate. In such an embodiment, an extractant, such as water, may optionally be added to second column 108 via line 127 . If the extractant comprises water, it can be obtained from an external source or from an internal return/recycle line from one or more other columns. In a preferred embodiment, water in the third residue of third column 109 is utilized as the extractant. As shown in Figures 1A, 1B, and 1C, the third residue can optionally be directed to second column 108 via line 121'.

Although the temperature and pressure of the second column 108 can vary, the temperature of the second residue exiting the second column 108 in line 118 is preferably from 60°C to 90°C, such as 70°C to 90°C or 80°C when at atmospheric pressure. ℃-90℃. The temperature of the second distillate exiting second column 108 in line 120 is preferably from 50°C to 90°C, eg, from 60°C to 80°C or from 60°C to 70°C. Column 108 can operate at atmospheric pressure. In other embodiments, the pressure of the second column 108 may be 0.1KPa-510KPa, such as 1KPa-475KPa or 1KPa-375KPa. Exemplary components of the distillate and residue compositions of second column 108 are provided in Table 4 below. It is understood that the distillates and residues may also contain other components not listed, such as components in the feed.

The weight ratio of ethanol in the second residue to ethanol in the second distillate is preferably at least 3:1, such as at least 6:1, at least 8:1, at least 10:1 or at least 15:1. The weight ratio of ethyl acetate in the second residue to ethyl acetate in the second distillate is preferably less than 0.4:1, such as less than 0.2:1 or less than 0.1:1. In embodiments using an extraction column with water as the extractant as the second column 108, the weight ratio of ethyl acetate in the second residue to ethyl acetate in the second distillate is close to zero. Thus, as shown in Table 4, the second distillate in line 120, which is a derivative stream of the crude ethanol product, contains a significant amount of denaturant separated in situ, and the second residue in line 118 contains a significant amount of denaturant. amount of ethanol. In some embodiments, the second distillate comprises diethyl ether. Diethyl ether may be present in an amount ranging from 0.1 wt.% to 20 wt.%, such as 0.1 wt.% to 10 wt.%, 1 wt.% to 9 wt.%, or 3 wt.% to 7 wt.%. In these cases, the second distillate may be a denatured ethanol composition with diethyl ether denaturant. In one embodiment, the second residue in line 118 also includes isopropanol. Isopropanol can be derived from acetone by the method described above. Acetone can, for example, be formed in situ in the hydrogenation and/or acetone can be added as a reactant to the hydrogenation reactor. Thus, in embodiments wherein a sufficient amount, such as 0.1 wt.% to 10 wt.%, 1 wt.% to 9 wt.%, or 3 wt.% to 7 wt.% of isopropanol is present in the second residue, the second The residue may be a denatured ethanol composition with isopropanol denaturant.

In another embodiment of the invention as shown in FIG. 1A , at least a portion of the second distillate is directed to purified ethanol exiting third column 109 , eg, via line 120 . In this case, the denatured ethanol composition results from the addition of an in situ formed denaturant to purified ethanol. Preferably, the ethyl acetate denaturant in the second distillate is combined with the purified ethanol obtained from the third column 109 . In other embodiments, the acetaldehyde denaturant in the second distillate is combined with the purified ethanol obtained from the third column 109 . In other embodiments, at least a portion of the second distillate is fed to third column 109 . In these cases, at least a portion of the denaturant, such as ethyl acetate and/or acetaldehyde, in the second distillate is passed through third column 109 along with the ethanol. Other impurities in the second distillate can be removed in the third column 109 residue. As a result, the third distillate contains ethanol along with the denaturant from the second column distillate. The denatured ethanol composition so formed can have the characteristics and composition of the denatured ethanol composition discussed herein. The weight ratio of the denaturant-containing stream, such as line 120, to the purified ethanol stream varies widely and can be adjusted to obtain a particular desired concentration of denaturant in the denatured ethanol composition. For example, when ethyl acetate is the denaturant, the weight ratio of the purified ethanol stream to the denaturant-containing stream may range from 100:1 to 1:1, eg, from 25:1 to 5:1.

In another embodiment, at least a portion of the second distillate is recycled to reactor 103 (not shown). As shown, the second residue from the bottom of second column 108 , which comprises ethanol and water, is fed to third column 109 (also referred to as the "product column") via line 118 . More preferably, the second residue in line 118 is introduced into the lower portion of third column 109, such as the lower half or third. Third column 109 recovers ethanol (preferably substantially pure except for azeotropic water content) as a distillate in line 119 . The distillate from the third column 109 is preferably refluxed as shown in Figure 1A, for example at a reflux ratio of 1:10-10:1, such as 1:3-3:1 or 1:2-2:1. The third residue in line 121 , which preferably consists primarily of water, is preferably removed from system 100 or may be partially returned to any part of system 100 . The third column 109 is preferably a tray column as described above and preferably operates at atmospheric pressure. The temperature of the third distillate exiting third column 109 in line 119 is preferably from 60°C to 110°C, for example from 70°C to 100°C or from 75°C to 95°C. When the column is operated at atmospheric pressure, the temperature of the third residue exiting the third column 109 is preferably from 70°C to 115°C, eg 80°C to 110°C or 85°C to 105°C. Exemplary components of the third column 109 distillate, residue, and optional sidestream compositions are provided in Table 5 below. As shown in Table 5, the third distillate may contain significant amounts of isopropanol denaturant. In these cases, the third distillate can be a denatured ethanol composition. It is understood that the distillates and residues may also contain other components not listed, such as components in the feed.

Since the separation takes place in the third column, the composition of the stream to be separated can be varied plate by plate in the third column. In some embodiments, the composition of the stream in the third column (depending on the operating conditions) may contain increased concentrations or accumulations of alcohols, for example boiling below water and above the intermediate boiling point of the ethanol/water low boiling azeotrope ( mid-boiling) alcohol. Examples of these alcohols include n-propanol (BP97.1°C), isopropanol (BP82.5°C) and 2-butanol (BP99.5°C). Some of these alcohols are formed in situ by the hydrogenation of acetic acid. Preferably, these in situ formed intermediate boiling alcohols can be used as denaturants.

One or more side streams 138 withdrawn from third column 109 may be used to remove intermediate boiling alcohols. Preferably, side stream 138 is taken from the middle or upper portion of third column 109 (above the feed point of the second residue). Most preferably, sidestream 138 is withdrawn from above tray 25 , such as from above tray 30 or from above tray 40 . By adjusting the process parameters of third column 109 and withdrawing sidestream 138 at appropriate locations, sidestream 138 advantageously removes a substantial portion of the intermediate boiling alcohol, such as n-propanol, from the feed in line 118 . The side stream 138 preferably comprises 0.01 wt.% to 10 wt.%, such as 0.01 to 5 wt.% or 0.01 wt.% to 3 wt.% n-propanol. By taking side stream 138, a significant amount of n-propanol is removed to purify the ethanol in the third distillate in line 119. It is within the scope of the invention to select the appropriate tray in the column from which to obtain a particular sidestream based on column configuration and operating conditions. Additionally, the contents of sidestream 138 may constitute a denatured ethanol composition comprising ethanol and n-propanol. Thus, in this embodiment, a pure ethanol composition can be co-produced with a denatured ethanol composition. In other embodiments, the sidestream 138 and the third distillate are each independently of the other a denatured ethanol composition. For example, sidestream 130 may comprise an n-propanol-denatured ethanol composition and third distillate 119 may comprise an ethyl acetate-denatured ethanol composition. By separating in this manner, the resulting third distillate 119 advantageously contains less n-propanol. In other embodiments, at least a portion of withdrawn sidestream 138 may be combined with third distillate 119 to form a denatured ethanol composition comprising at least a portion of the in-situ formed denaturant from sidestream 130 .

Any compounds carried over from the feed or crude reaction product during the distillation typically remain in an amount of less than 0.1 wt.%, such as less than 0.05 wt.% or less than 0.02 wt.%, based on the total weight of the third distillate composition in the third distillate. In one embodiment, one or more side streams may remove impurities from any of columns 107 , 108 , and/or 109 of system 100 . In one embodiment, at least one side stream may be used to remove impurities from third column 109. Impurities may be purged and/or retained within the system 100 .

The third distillate in line 119 may be further purified using one or more additional separation systems, such as distillation columns (eg, work-up columns) or molecular sieves, to form an anhydrous ethanol product stream, ie, "finished anhydrous ethanol."

Returning now to second column 108, the distillate in line 120 is preferably as shown in Figures 1A, 1B and 1C, for example at 1:10-10:1, such as 1:5-5:1 or 1:3- Reflux at a reflux ratio of 3:1. As noted above, the second distillate contains a significant portion of denaturants such as ethyl acetate and/or acetaldehyde. Thus, all or a portion of the second distillate can be directed downstream as shown in line 120 and can be combined with ethanol that is further purified, eg, by third column 109 . Additionally, at least a portion of the distillate from second column 108 may be purged if necessary. In another embodiment, as shown in FIG. 1B , a portion of the second distillate from second column 108 can be recycled to reaction zone 101 via line 120 to convert ethyl acetate to additional ethanol, e.g., Can be recycled to reactor 103 and fed along with acetic acid feed line 105 . In another embodiment, the second distillate in line 120 can be further purified to remove other components, such as acetaldehyde, using one or more additional columns (not shown). Such a configuration can be used in situations where the desired denaturant consists essentially of ethyl acetate, such as in Part 21 (Part) of the US Code of Code of Federal Regulations, Title 27 (hereinafter abbreviated as 27C.F.R.Part21). Formula 35 or 35-A (herein incorporated by reference in its entirety). As another option, an additional column (not shown) can be used to remove ethyl acetate and leave acetaldehyde behind, which can be useful in cases where the desired denaturant contains acetaldehyde but not ethyl acetate.

System 100 in Figure 1C is similar to that of Figures IA and IB, except that the second distillate in line 120 is fed to a fourth column 123, also referred to as the "acetaldehyde removal column". In fourth column 123 , the second distillate is separated into a fourth distillate comprising acetaldehyde in line 124 and a fourth residue comprising ethyl acetate in line 125 . The fourth distillate is preferably refluxed at a reflux ratio of 1:20-20:1, for example 1:10-10:1 or 1:5-5:1, at least part of the fourth distillate may pass through line as shown 124 returns to the reaction zone 101. For example, the fourth distillate can be combined with the acetic acid feed, added to evaporator 110 , or added directly to reactor 103 . The fourth distillate is co-fed to evaporator 110 with acetic acid in line 105 as shown. Without being bound by theory, since acetaldehyde can be hydrogenated to form ethanol, recycling the acetaldehyde-containing stream to the reaction zone increases the yield of ethanol and reduces by-product and waste generation. In another embodiment (not shown in the figure), acetaldehyde can be collected and utilized with or without further purification to produce compounds including but not limited to n-butanol, 1,3-butanediol and and/or useful products of crotonaldehyde and derivatives. In a preferred embodiment, acetaldehyde is removed from the second distillate in fourth column 123 such that no detectable amount of acetaldehyde is present in the residue of column 123 .

In a preferred embodiment, at least a portion of the fourth distillate is combined (not shown) with the purified ethanol stream to form a denatured ethanol composition. Preferably, the denaturant comprises acetaldehyde and/or ethyl acetate. In other embodiments, at least a portion of the fourth distillate may be fed to third column 109 . As a result, in these embodiments, the distillate exiting third column 109 may comprise at least a portion of the in situ formed acetaldehyde and/or ethyl acetate present in the fourth distillate. In these embodiments, the weight percent of acetaldehyde denaturant in the denatured ethanol composition can be as previously discussed. The weight ratio of purified ethanol stream to fourth distillate can vary widely and can be adjusted to obtain a specific desired concentration of denaturant in the denatured ethanol composition. For example, the weight ratio of the purified ethanol stream to the fourth distillate may be from 2:1 to 75:1, such as from 7:1 to 50:1.

The fourth residue mainly contains ethyl acetate and ethanol. Preferably, at least a portion of the fourth residue is combined with the purified ethanol stream to form a denatured ethanol composition. Preferably, the denaturant comprises ethyl acetate. In other embodiments, at least a portion of the fourth residue may be fed to third column 109 . As a result, in these embodiments, the distillate exiting third column 109 may comprise at least a portion of the in situ formed ethyl acetate present in the fourth residue. In these embodiments, the weight percent of ethyl acetate denaturant in the denatured ethanol composition can be as previously discussed. The weight ratio of the purified ethanol stream to the fourth residue can vary widely and be adjusted to obtain a particular desired concentration of denaturant in the denatured ethanol composition. For example, the weight ratio of the purified ethanol stream to the fourth residue may be from 1:1 to 50:1, such as from 1.75:1 to 20:1. In other embodiments, the fourth residue from fourth column 123 may be purged via line 125 .

The fourth column 123 is preferably a tray column as described above and preferably operates at superatmospheric pressure. In one embodiment, the pressure is 120KPa-5000KPa, such as 200KPa-4,500KPa or 400-3000KPa. In a preferred embodiment, fourth column 123 may operate at a higher pressure than the other columns.

The temperature of the fourth distillate exiting fourth column 123 in line 124 is preferably from 60°C to 110°C, eg, from 70°C to 100°C or from 75°C to 95°C. The temperature of the residue exiting the fourth column 125 is preferably from 70°C to 115°C, eg 80°C to 110°C or 85°C to 110°C. Exemplary components of the distillate and residue compositions of fourth column 123 are provided in Table 6 below. It is understood that the distillates and residues may also contain other components not listed, such as components in the feed.

FIG. 1C also shows that the third residue in line 121 can be recycled to second column 108 . In one embodiment, recycling the third residue further reduces the aldehyde components in the second residue and concentrates these aldehyde components in distillate stream 120 and from there to fourth column 123, wherein The aldehydes can be more easily separated in the fourth column 123 . These embodiments also provide a finished ethanol product that preferably has low amounts of aldehydes and esters.

In several embodiments, the denaturant-containing stream is combined with the purified ethanol stream to form a denatured ethanol composition. In other embodiments, these denaturant-containing streams may be fed to third column 109 rather than combined with the distillate from third column 109 . In these cases, the denaturant fed to column 109 may be separated in the distillate of third column 109, and as such may be present in the purified ethanol. Accordingly, the third distillate may comprise a denatured ethanol composition.

As mentioned above, the denatured ethanol composition obtained by the method of the present invention comprises ethanol and at least one, such as at least two or at least three denaturants. The denaturant can be generated in situ by a hydrogenation reaction, thus eliminating the need for an external source of denaturant. Preferably, the denaturant comprises ethyl acetate, acetaldehyde, diethyl ether, acetic acid, isopropanol and/or mixtures thereof.

The denaturant so produced should be present in an effective amount, eg, an amount sufficient to provide a denatured ethanol composition in accordance with appropriate government regulations. As used herein, the term "denatured ethanol composition" refers to a composition comprising ethanol and one or more denaturants that are not suitable for use in beverages or medical pharmaceuticals, such as unpalatable. In other embodiments, the denatured ethanol may comprise "specially denatured ethanol," which is an ethanol composition that has been denatured according to a recipe approved under 27 C.F.R. Part 21, Subpart D. Furthermore, denatured ethanol requires different requirements for different applications, such as fuel applications and industrial applications. Therefore, some applications may require higher amounts of denaturant while others may require lower amounts. 27 C.F.R. Part 21, which is hereby incorporated by reference in its entirety, provides a listing of some of these applications. Table 7 shows some denaturing compositions according to the amount of denaturant added to 100 gallons of ethanol.

^* Ethanol not less than 160proof.

Furthermore, in other embodiments, the denatured ethanol compositions of the present invention correspond to denatured formulations of countries other than the United States when formed. For example, in the UK, one recipe for commercial special denatured alcohol is as follows. Not less than 20 parts by volume of ethyl acetate and 1 part by volume of isopropanol are mixed per 979 parts by volume of alcohol (the concentration of which is not less than 85% by volume of alcohol).

Another exemplary UK specific denatured alcohol formula is as follows. Not less than 50 parts by volume of isopropanol is mixed per 950 parts by volume of alcohol (the concentration of which is not less than 85% alcohol by volume).

Of course, this list of US and international denatured ethanol composition formulations is not exhaustive, and other formulations are of course within the scope of the present invention.

Preferably, the denatured ethanol composition comprises 50wt.%-99wt.%, such as 60wt.%-99wt.% or 70wt.%-95wt.%, of ethanol based on the total weight of the denatured ethanol composition, and 0.01wt.%- 40wt.%, such as 0.01wt.%-25wt.%, 0.01wt.%-20wt.%, or 1wt.%-15wt.% of denaturant.

In addition to ethanol and denaturants, denatured ethanol compositions may also contain only trace amounts of other impurities such as acetic _acid ; C3 alcohols such as n-propanol and isopropanol; and/or _C4 - _C5 alcohols.

In some embodiments, as discussed above, the denatured ethanol composition of the present invention comprises at least a portion of the first column distillate. At this time, the denatured ethanol composition may contain ethyl acetate and/or acetaldehyde as a denaturant. Exemplary weight percent ranges for ethanol and denaturant (and other optional components) are provided in Table 3 above. Preferably, the total amount of denaturants (ethyl acetate and acetaldehyde) in these denatured ethanol compositions is 0.01wt.%-90wt.%, such as 0.01wt.%-65wt.% or 0.01wt.%-34wt.% denaturant.

In other embodiments, the denatured ethanol composition is withdrawn from a separation column in the separation zone. In these cases, the ethanol composition may, for example, comprise an isopropanol denaturant in an amount of 0.1 wt.% to 10 wt.%, such as 1 wt.% to 9 wt.% or 3 wt.% to 7 wt.% isopropanol.

In other embodiments, the ethanol composition comprises diethyl ether in an amount of 0.1 wt.% to 20 wt.%, such as 0.1 wt.% to 10 wt.%, 1 wt.% to 9 wt.%, or 3 wt.% to 7 wt.% diethyl ether For example, diethyl ether is a denaturant. In other embodiments, the ethanol composition comprises an acetic acid denaturant in an amount of 0.1 wt.% to 20 wt.%, such as 1 wt.% to 15 wt.% or 2 wt.% to 12 wt.% acetic acid. In other embodiments, the ethanol composition comprises 0.001-wt.%-10wt.%, such as 0.001-0.1wt.%, 0.1wt.%-10wt.%, 1wt.%-9wt.%, or 3wt. n-propanol denaturant in an amount of %-7wt.% n-propanol.

In a preferred embodiment, the denatured ethanol composition is formed by combining a denaturant-containing crude ethanol product derived stream, such as a second distillate, with a purified ethanol stream. Exemplary weight percent ranges for ethanol and denaturants such as ethyl acetate and/or acetaldehyde (and other optional components) are provided in Table 8. In some embodiments, the ethanol composition comprises 0.01 wt.%-40 wt.%, such as 0.01 wt.%-15 wt.%, 0.01 wt.%-10 wt.%, or 0.01 wt.%-9 wt.% of ethyl acetate amount of ethyl acetate denaturant. In other embodiments, the ethanol composition comprises acetaldehyde in an amount of 0.01 wt.%-10 wt.%, such as 0.01 wt.%-5 wt.%, 0.01 wt.%-2 wt.%, or 0.01 wt.%-1 wt.% acetaldehyde denaturant. Preferably, the total amount of denaturant in these denatured ethanol compositions is 0.01wt.%-20wt.%, such as 0.01wt.%-12wt.% or 0.01wt.%-10wt.% of denaturant.

In other embodiments, although exemplary weight percents of water in the embodiments of Table 8 range from 0.0001 wt.% to 1 wt.%, water may be present in the denatured ethanol composition in larger amounts. For example, the denatured ethanol composition may comprise water in an amount of 0.1 wt.% to 8 wt.%, such as 0.1 wt.% to 5 wt.% or 0.1 wt.% to 2 wt.% water.

Denatured ethanol compositions produced by embodiments of the present invention may be suitable for use in a variety of applications, including fuels, solvents, chemical feedstocks, pharmaceutical products, detergents, sanitizers, or hydroconversion. In fuel applications, the denatured ethanol composition can be blended with gasoline for use in motor vehicles such as automobiles, boats and small piston engine aircraft. In non-fuel applications, the denatured ethanol composition can be used as a solvent for cosmetics and cosmetic preparations, detergents, disinfectants, paints, inks and pharmaceuticals. The denatured ethanol composition can also be used as a processing solvent in manufacturing processes such as pharmaceutical products, food preparation, dyes, photochemical and latex processing.

The denatured alcohol composition can also be used as a chemical feedstock to make other chemicals such as vinegar, ethyl acrylate, ethyl acetate, ethylene, glycol ethers, ethylamines, aldehydes and higher alcohols, especially butanol. The denatured ethanol composition may be suitable for use as a feedstock in ester production. Preferably, in the preparation of ethyl acetate, the denatured ethanol composition may be esterified with acetic acid or reacted with polyvinyl acetate. The denatured ethanol composition can be dehydrated to produce ethylene. Ethanol can be dehydrated using any known dehydration catalyst, such as those described in U.S. Publication Nos. 2010/0030001 and 2010/0030002, the entire contents and disclosure of which are hereby incorporated by reference herein . For example, zeolite catalysts can be used as dehydration catalysts. Preferably, the zeolite has a pore size of at least about 0.6 nm, and preferred zeolites include dehydration catalysts selected from the group consisting of mordenite, ZSM-5, zeolite X, and zeolite Y. For example, Zeolite X is described in US Patent No. 2,882,244 and Zeolite Y is described in US Patent No. 3,130,007, which are hereby incorporated by reference in their entirety.

In order that the invention disclosed herein may be more effectively understood, some non-limiting examples are provided below. The following examples describe various embodiments of the ethanol compositions of the present invention.

Example

Example 1

At an average temperature of 291 °C and an outlet pressure of 2,063 KPa, a gasification feed containing 95.2 wt.% acetic acid and 4.6 wt.% water was reacted with hydrogen in the presence of a catalyst to produce Caide ethanol product of esters, the catalyst comprising 1.6 wt.% platinum and 1 wt.% tin supported on a 1/8 inch calcium silicate modified silica extrudate. Unreacted hydrogen was recycled back to the reactor inlet to give a total hydrogen/acetic acid molar ratio of 5.8 at a GHSV of 3,893 hr ⁻¹ . Under these conditions, 42.8% of acetic acid was converted with a selectivity of 87.1% for ethanol, 8.4% for ethyl acetate and 3.5% for acetaldehyde. The crude ethanol mixture was purified using a separation scheme with a distillation column as shown in Figure 1A.

The crude ethanol product was fed into the first column at a feed rate of 20 g/min. The composition of the liquid feed is provided in Table 8. The first column was a 2 inch diameter Oldershaw with 50 trays. The column was operated at a temperature of 115°C at atmospheric pressure. Unless otherwise indicated, the column operating temperature is the temperature of the liquid in the reboiler, and the pressure at the top of the column is atmospheric pressure (about one atmosphere). The column pressure difference between trays in the first column is 7.4KPa. The first residue was withdrawn at a flow rate of 12.4 g/min and returned to the hydrogenation reactor.

The first distillate was condensed and refluxed in a 1:1 ratio at the top of the first column, and a portion of the distillate was introduced into the second column at a feed rate of 7.6 g/min. The second column was a 2 inch diameter Oldershaw design equipped with 25 trays. The second column was operated at a temperature of 82°C at atmospheric pressure. In this embodiment, no extractant is used. The column pressure difference between trays in the second column is 2.6KPa. The second residue was withdrawn at a flow rate of 5.8 g/min and directed to the third column. The second distillate was refluxed at a ratio of 4.5:0.5 and the remaining distillate was collected for analysis. The compositions of the feed, distillate and residue are provided in Table 9.

As shown in Table 9, the first column distillate is a denatured ethanol composition comprising ethanol and a significant portion of the in situ forming denaturant.

The residue from the second column was collected from several passes and introduced into the third column, a 2 inch Oldershaw containing 60 trays, at a rate of 10 g/min above the 25th tray. The third column was operated at a temperature of 103°C at atmospheric pressure. The column pressure difference between trays in the third column is 6.2KPa. The third residue was withdrawn at a flow rate of 2.7 g/min. The third distillate was condensed and refluxed at the top of the third column in a 3:1 ratio. In Table 10 the composition of the recovered ethanol composition is shown. The ethanol composition comprises ethanol and a substantial portion of ethyl acetate formed in situ. Surprisingly and unexpectedly, the denatured ethanol composition is a denatured ethanol composition prepared without an added denaturant. The ethanol composition also contained 10 ppm of n-butyl acetate.

Example 2

At an average temperature of 290°C and an outlet pressure of 2,049KPa, a gasification feed containing 96.3 wt.% acetic acid and 4.3 wt.% water was reacted with hydrogen in the presence of a catalyst to produce Caide ethanol product of esters, the catalyst comprising 1.6 wt.% platinum and 1 wt.% tin supported on a 1/8 inch calcium silicate modified silica extrudate. Unreacted hydrogen was recycled back to the reactor inlet to give a total hydrogen/acetic acid molar ratio of 10.2 at a GHSV of 1,997 hr ⁻¹ . Under these conditions, 74.5% of the acetic acid was converted with a selectivity of 87.9% for ethanol, 9.5% for ethyl acetate and 1.8% for acetaldehyde. The crude ethanol mixture was purified using a separation scheme with a distillation column as shown in Figure 1A.

The crude ethanol product was fed into the first column at a feed rate of 20 g/min. The composition of the liquid feed is provided in Table 11. The first column was a 2 inch diameter Oldershaw with 50 trays. The column was operated at a temperature of 116°C at atmospheric pressure. The column pressure difference between trays in the first column is 8.1KPa. The first residue was withdrawn at a flow rate of 10.7 g/min and returned to the hydrogenation reactor.

The first distillate was condensed and refluxed in a 1 :1 ratio at the top of the first column and a portion of the distillate was introduced into the second column at a feed rate of 9.2 g/min. The second column was a 2 inch diameter Oldershaw design equipped with 25 trays. The second column was operated at a temperature of 82°C at atmospheric pressure. The column pressure difference between trays in the second column is 2.4KPa. The second residue was withdrawn at a flow rate of 7.1 g/min and directed to the third column. The second distillate was refluxed at a ratio of 4.5:0.5 and the remaining distillate was collected for analysis. The compositions of the feed, distillate and residue are provided in Table 11.

As shown in Table 11, the first column distillate is a denatured ethanol composition comprising ethanol and a significant portion of the in situ forming denaturant.

Example 3

At an average temperature of 291°C and an outlet pressure of 1,420KPa, a gasification feed containing 98 wt.% acetic acid and 2 wt.% acetone was reacted with hydrogen in the presence of a catalyst to produce Ethyl acetate caide ethanol product, the catalyst comprising 1.6 wt.% platinum and 1 wt.% tin supported on a 1/8 inch calcium silicate modified silica extrudate. The catalyst was diluted with 3mm glass beads in a 1:1 volume ratio. Under these conditions, the acetone conversion was 68%, and after separation, the resulting ethanol/isopropanol mixture contained 4.3 wt.% isopropanol.

The composition of the resulting caide ethanol composition is provided in Table 12.

As shown in Table 12, when the acetic acid feed was subjected to hydrogenation, the addition of acetone to the acetic acid feed provided the isopropanol product. The caide ethanol product formed from hydrogenation provided a denatured ethanol composition comprising ethanol and 4.3 wt.% of isopropanol formed in situ.

In other embodiments, the denatured ethanol composition is formed by combining a crude ethanol product derived stream comprising a denaturant with a purified ethanol stream. As such, the denaturant from the derived stream is combined with the purified ethanol stream.

Example 4

The production of a crude ethanol product comprising ethanol, acetic acid, acetaldehyde, water, and ethyl acetate by hydrogenation of acetic acid is discussed above. The crude ethanol product was purified using a separation scheme with a distillation column as shown in Figure 1A. The second column operates as an extractive distillation column with water extractant.

In Table 13 the compositions of the distillate exiting the second column and the distillate exiting the third column are provided.

The second and third distillates of Table 13, when combined in weight ratios of 1.6:1 and 21:1 respectively, provided denatured ethanol compositions as shown in Table 14.

Example 5

The production of a crude ethanol product comprising ethanol, acetic acid, acetaldehyde, water, and ethyl acetate by hydrogenation of acetic acid is discussed above. The crude ethanol product was purified using a separation scheme with a distillation column as shown in Figure 1C.

In Table 15 the composition of the residue exiting the fourth column and the distillate exiting the third column is provided.

The third distillate and fourth residue of Table 15, when combined in weight ratios of 1.75:1 and 20:1 respectively, provided denatured ethanol compositions as shown in Table 16.

Example 6

The production of a crude ethanol product comprising ethanol, acetic acid, acetaldehyde, water, and ethyl acetate by hydrogenation of acetic acid is discussed above. The crude ethanol product was purified using a separation scheme with a distillation column as shown in Figure 1C.

In Table 17 the compositions of the distillate exiting the fourth column and the distillate exiting the third column are provided.

The third and fourth distillates of Table 17, when combined in weight ratios of 7:1 and 50:1 respectively, provided denatured ethanol compositions as shown in Table 18.

Example 7

The production of a crude ethanol product comprising ethanol, acetic acid, acetaldehyde, water, and ethyl acetate by hydrogenation of acetic acid is discussed above. The crude ethanol product was purified using a separation scheme with a distillation column as shown in Figure 1A.

In Table 19 the compositions of the distillate exiting the first column and the distillate exiting the third column are provided.

The third and first distillates of Table 19, when combined in weight ratios of 0.05:1 and 3:1, respectively, provided denatured ethanol compositions as shown in Table 20.

Example 8

The production of a crude ethanol product comprising ethanol, acetic acid, acetaldehyde, water, and ethyl acetate by hydrogenation of acetic acid is discussed above. The crude ethanol product can be purified using the first column. In this separation scheme, however, it is possible to send the first distillate directly to the third column, thus bypassing the second and/or fourth column. A third column can provide residue and distillate. In Table 24 the compositions of the first and third distillates are provided. The third distillate is a denatured ethanol composition which can advantageously be produced without the need for a second or fourth column.

Example 9

The production of a crude ethanol product comprising ethanol, acetic acid, acetaldehyde, water, and ethyl acetate by hydrogenation of acetic acid is discussed above. The crude ethanol product was purified using a separation scheme as shown in Figure 1A, inter alia, with first and second distillation columns.

The residue from the second column was collected from several passes and introduced into the third column, a 2 inch Oldershaw containing 50 trays, at a rate of 18 g/min. The third column was operated at a temperature of 102°C at atmospheric pressure. The column pressure difference between trays in the third column is 6.2KPa. The third residue was withdrawn at a flow rate of 13 g/min. The third distillate was condensed and refluxed at the top of the third column in a 3:2 ratio.

The composition of some of the components in the second residue stream at various tray positions within the third column is shown in FIG. 2 . Ethanol was also present in significant amounts at each tray.

As shown in Figure 2, a side stream can be taken from the third column. Preferably, the withdrawn side stream comprises ethanol and n-propanol. The side stream withdrawn from the third column provides a denatured ethanol composition comprising ethanol and n-propanol. In some embodiments, the side stream can be combined with a purified ethanol stream, such as a third distillate, to form a single denatured ethanol composition. Surprisingly and unexpectedly, each of these denatured ethanol compositions can be prepared without the addition of external denaturants.

In the example of FIG. 2, the side stream may be taken at trays 22-52, eg, tray 25-tray 43; tray 25-tray 40; or tray 26-tray 39. However, the example of FIG. 2 is merely exemplary. It is within the scope of the invention to adjust the sidestream withdrawal location based on process parameters to achieve the desired sidestream composition.

Having described the invention in detail, various modifications within the spirit and scope of the invention will become apparent to those skilled in the art. In view of the foregoing discussion, the relevant knowledge in the art and references discussed above in relation to the Background and Detailed Description, the disclosures of which are hereby incorporated by reference in their entirety. Furthermore, it is to be understood that aspects of the invention, as well as various embodiments and portions of features recited below and/or in the appended claims may be combined or interchanged in part or in whole. In the foregoing description of each embodiment, an embodiment referring to another embodiment may be appropriately combined with other embodiments as can be recognized by those skilled in the art. Furthermore, those skilled in the art will appreciate that the foregoing description is by way of example only, and is not intended to limit the invention.

Claims (35)

1. A method of producing a denatured ethanol composition, the method comprising: hydrogenating the acetic acid feed in the presence of a catalyst in a reactor from which a caide ethanol product comprising ethanol and at least one denaturant is continuously withdrawn; separating the crude ethanol product into an ethanol stream and at least one derivative stream comprising said at least one denaturant; further purifying the ethanol stream to form a purified ethanol stream; and combining at least a portion of the at least one derived stream with a purified ethanol stream to produce a denatured ethanol composition; wherein the denatured ethanol composition comprises 50-99 wt.% ethanol and 0.01 wt.%-40 wt.% of the at least one denaturant based on the total weight of the denatured ethanol composition; and Wherein said at least one denaturant comprises acetaldehyde. 2. The method of claim 1, wherein said at least one denaturant further comprises at least one selected from the group consisting of aldol, diethyl ether, ethyl acetate, isopropanol, acetic acid, and methanol. 3. The method of claim 1, wherein said at least one denaturant further comprises ethyl acetate. 4. The method of any one of claims 1-3, wherein the at least one denaturant further comprises isopropanol. 5. The method of any one of claims 1-3, wherein the at least one denaturant further comprises diethyl ether. 6. The method of any one of claims 1-3, wherein the at least one denaturant further comprises acetic acid. 7. The method of any one of claims 1-3, wherein the denatured ethanol composition comprises 50 wt.% to 99 wt.% ethanol. 8. The process of any one of claims 1-3, wherein the acetic acid feed comprises acetic acid and propionic acid. 9. The method of claim 8, wherein propionic acid is hydrogenated to produce n-propanol. 10. The method of claim 9, further comprising: separating at least a portion of the crude ethanol product in a first column into a first distillate comprising ethanol and n-propanol, and a first residue comprising acetic acid; separating at least part of the first distillate in a second column into a second distillate and a second residue comprising ethanol, at least part of n-propanol and water; and At least part of the second residue is separated in a third column into a third distillate comprising ethanol and a third residue comprising water. 11. The method of claim 10, further comprising: A side stream comprising n-propanol is withdrawn from the third column. 12. The method of any one of claims 1-3, wherein the caide ethanol product further comprises: Based on the total weight of the crude ethanol product, 0.01wt.%-20wt.% ethyl acetate; 0.01wt.%-10wt.% acetaldehyde; 0.01wt.%-10wt.% isopropanol; 0.01wt.%-20wt.% diethyl ether; 0wt.%-90wt.% acetic acid; and 5wt.%-35wt.% water. 13. The process of any one of claims 1-3, wherein the acetic acid feed comprises acetic acid and acetone, and the at least one denaturant comprises isopropanol. 14. The process of any one of claims 1-3, further comprising contacting the acetic acid with hydrogen in the auxiliary reactor under conditions effective to form acetone. 15. The method of any one of claims 1-3, wherein the denatured ethanol composition comprises 0.1 wt.% to 10 wt% isopropanol based on the total weight of the denatured ethanol composition. 16. The method of any one of claims 1-3, wherein said separating comprises: separating a first portion of the crude ethanol product into an ethanol stream and one or more derivative streams; and A second portion of the crude ethanol product is combined with the purified ethanol stream to form a denatured ethanol composition. 17. The method of any one of claims 1-3, wherein said separating comprises: separating at least a portion of the crude ethanol product into an ethanol stream and one or more derivative streams; and Combining at least a portion of the acetic acid feed with the purified ethanol stream forms a denatured ethanol composition. 18. The method of any one of claims 1-3, wherein said separating comprises: At least a portion of the crude ethanol product is separated in a first column into a first distillate comprising ethanol, acetaldehyde, and ethyl acetate, and a first residue comprising acetic acid. 19. The method of claim 18, further comprising: separating at least a portion of the first distillate into an ethanol stream and a denaturant stream comprising at least one denaturant comprising acetaldehyde and ethyl acetate; and Combining at least a portion of the denaturant stream with the purified ethanol stream to form a denatured ethanol composition. 20. The method of claim 18, further comprising: separating at least a portion of the first distillate into an ethanol stream; and Combining at least a portion of the first residue with the purified ethanol stream forms a denatured ethanol composition. 21. The method of claim 18, further comprising: separating at least part of the first distillate into a second distillate comprising ethyl acetate and/or acetaldehyde, and an ethanol stream in a second column; and At least a portion of the second distillate is combined with the purified ethanol stream to form a denatured ethanol composition. 22. The method of claim 21, wherein the second column is an extractive distillation column. 23. The method of claim 21, further comprising: separating at least a portion of the first distillate into a second residue comprising ethyl acetate, and an ethanol stream in a second column; and At least a portion of the second residue is combined with the purified ethanol stream to form a denatured ethanol composition. 24. The method of claim 23, wherein the second column is a non-extractive distillation column. 25. The method of claim 18, further comprising: separating at least part of the first distillate into a second residue comprising ethyl acetate, and an ethanol stream in a second column; At least part of the second residue is separated in a third column into a third distillate comprising ethyl acetate and ethanol. 26. The method of any one of claims 1-3, wherein the denaturant comprises ethyl acetate, and wherein the denatured ethanol composition further comprises: Based on the total weight of the crude ethanol product, 0.01wt.%-40wt.% ethyl acetate; 50wt.%-99wt.% ethanol; and 1wt.%-35wt.% water. 27. The method of any one of claims 1-3, wherein the denaturant comprises acetaldehyde, and wherein the denatured ethanol composition further comprises: Based on the total weight of the crude ethanol product, 0.01wt.%-10wt.% acetaldehyde; 50wt.%-99wt.% ethanol; and 1wt.%-35wt.% water. 28. The method of any one of claims 1-3, wherein the denaturant comprises isopropanol, and wherein the denatured ethanol composition further comprises: Based on the total weight of the crude ethanol product, 0.1wt.%-10wt.% isopropanol; 50wt.%-99wt.% ethanol; and 1wt.%-35wt.% water. 29. The method of any one of claims 1-3, wherein the denaturant comprises diethyl ether, and wherein the denatured ethanol composition further comprises: Based on the total weight of the crude ethanol product, 0.1wt.%-20wt.% diethyl ether; 50wt.%-99wt.% ethanol; and 1wt.%-35wt.% water. 30. The method of any one of claims 1-3, wherein the denaturant comprises acetic acid, and wherein the denatured ethanol composition further comprises: Based on the total weight of the crude ethanol product, 0.01wt.%-20wt.% acetic acid 50wt.%-99wt.% ethanol; and 1wt.%-35wt.% water. 31. The method of any one of claims 1-3, wherein the denaturant comprises n-propanol, and wherein the denatured ethanol composition further comprises: Based on the total weight of the crude ethanol product, 0.1wt.%-10wt.% n-propanol 50wt.%-99wt.% ethanol; and 1wt.%-35wt.% water. 32. A denatured ethanol composition formed by the method of any one of claims 1-31. 33. A fuel composition comprising the denatured ethanol composition of claim 32. 34. A feedstock comprising the denatured ethanol composition of claim 32 for ester production. 35. A solvent comprising the denatured ethanol composition of claim 32.