JP6046713B2 - Process of sulfone conversion with superelectron donors - Google Patents

Description

Related applications:
This application claims the benefit of Patent Document 1 filed on July 12, 2011, the disclosure of which is incorporated herein by reference.

  The process of the present invention relates to the removal of sulfur oxide-containing compounds after oxidative desulfurization of crude oil or distilled oil or comprehensive hydrodesulfurization / oxidative desulfurization. More specifically, the process of the present invention relates to a process for the decomposition of residual sulfones and sulfoxides after oxidative desulfurization.

  Crude oil is a major source of hydrocarbons used worldwide as fuel and petrochemical feedstock. Although the composition of natural oils or crude oils is quite diverse, all crude oils contain sulfur compounds and most contain nitrogen compounds, which may also contain oxygen, but most crude oxygen The content is low. Generally, crude oils have sulfur concentrations of less than about 5% by weight, and most crudes have sulfur concentrations in the range of about 0.5 to about 1.5% by weight. The nitrogen concentration is usually less than 0.2% by weight, but may be as high as 1.6% by weight.

  Crude oil is refined at refineries to produce transportation fuels and petrochemical feedstocks. In general, transportation fuel is produced by processing and blending fractions obtained from crude oil to meet specific end-use specifications. Since most of the crude oil currently available in large quantities is high in sulfur, the fraction must be desulfurized to obtain a product that meets performance standards and / or environmental standards.

  Sulfur-containing organic compounds in fuels are actually a major source of environmental pollution. Sulfur compounds are converted to sulfur oxides in the combustion process, producing sulfur oxyacids and contributing to particulate matter emissions. Oxygenated fuel blend compounds and compounds containing little or no carbon-carbon chemical bonds (eg, methanol and dimethyl ether) are known to reduce smoke and engine exhaust emissions. However, most compounds of this type have a high vapor pressure and / or are almost insoluble in diesel fuel and have low ignitability, as indicated by their cetane number. For example, refined diesel fuel with reduced sulfur and aroma content by chemical hydrotreating and hydrogenation also results in reduced fuel lubricity. Low lubricity diesel fuel can cause excessive wear of fuel pumps, injectors and other moving parts that come into contact with the fuel under high pressure. Middle distillates (fractions with a nominal boiling point in the range of 180 ° C. to 370 ° C.) are used as fuel or fuel blend components for compression ignition internal combustion engines (diesel engines). The intermediate extract usually contains about 1-3% by weight of sulfur. Since 1993, middle distillate standards in Europe and the United States have been reduced from 3000 parts per million (ppmw) to 5-50 ppmw.

  To comply with these ultra-low sulfur fuel regulations, refiners need to produce fuels with lower sulfur levels at refinery gates so that they can meet stringent standards after blending at the gate.

  A low pressure conventional hydrodesulfurization (HDS) process can be used to remove most of the sulfur from the petroleum distillate for refinery transportation fuel blends. The HDS device is not effective in removing sulfur from compounds in which the sulfur atoms are sterically shielded, such as polycyclic aromatic sulfur compounds, under mild conditions (ie, pressure 30 bar). This is especially true when the sulfur heteroatom is shielded by two alkyl groups (eg, 4,6-dimethyldibenzothiophene). These shielded dibenzothiophenes account for the majority at low sulfur levels, such as 50-100 ppmw. In order to remove sulfur from these difficult-to-treat sulfur compounds, severe operating conditions (ie higher hydrogen partial pressure, temperature, catalyst amount) must be applied. Increasing the hydrogen partial pressure can only be done by raising the purity of the recycle gas, otherwise a new grassroots device must be designed, which is an expensive option. The use of harsh operating conditions results in yield loss, reduced catalyst cycle and product quality degradation (eg, color).

Such shielded sulfur compounds will also need to be removed from distillate feedstocks and products in order to meet future stricter standards. This need has become the driving force for the development of new unconventional process technologies. Oxidative desulfurization is one known technique for reducing sulfur to low levels. However, unlike the situation widely practiced in hydrodesulfurization processes where sulfur is removed as H ₂ S and nitrogen is removed as NH ₃ , oxidative desulfurization involves oxidized sulfur compounds (eg, sulfoxide and sulfone). ) And nitrogen compounds. For example, in the oxidative desulfurization of 1000 tons of hydrogen-treated diesel that initially contains 500 ppmw of sulfur, 1 ton of sulfone is produced, assuming complete conversion. These oxidized compounds are then further removed by extraction or adsorption.

  Sulfur-containing compounds commonly present in hydrocarbon fuels include aliphatic molecules such as sulfides, disulfides and mercaptans, as well as thiophene, benzothiophene, dibenzothiophene and alkyl derivatives (eg, 4,6-dimethyl-dibenzothiophene). Aromatic molecules are included. These aromatic molecules have a higher boiling point than aliphatic molecules and as a result are more abundant in high-boiling fractions.

  Aliphatic sulfur compounds are easily desulfurized using hydrodesulfurization, but some hyperbranched aliphatic molecules can interfere with sulfur atom removal and are somewhat difficult to desulfurize.

  Of the sulfur-containing aromatic compounds, thiophene and benzothiophene are relatively easy to hydrodesulfurize, but the addition of an alkyl group to the ring compound slightly increases the difficulty of hydrodesulfurization. Dibenzothiophene obtained by adding another ring to benzothiophenes is directionally more difficult to desulfurize. The degree of difficulty varies greatly depending on the alkyl substitution, and di-beta substitution is the most difficult to desulfurize, which is the basis for the name “difficult to process”. These so-called beta substituents shield the heteroatoms from the active site of the catalyst. Thus, economical removal of so-called “refractory sulfur” is extremely difficult to achieve, so removing sulfur compounds in hydrocarbon fuels to a level of less than about 10 ppmw is not Technology is very expensive. In order to meet more stringent sulfur standards, these refractory sulfur compounds need to be removed from the hydrocarbon fuel stream.

  An option that could potentially reduce the sulfur level of a hydrocarbon stream economically could be to integrate an oxidation reaction zone into the hydrodesulfurization process. In the oxidation reaction zone, hydrocarbon-based sulfur compounds are readily converted to sulfur and oxygen containing compounds (eg, sulfoxides or sulfones) under very mild conditions. Because the converted compounds have different chemical and physical properties, it is possible to remove sulfur-containing compounds from the remainder of the original hydrocarbon stream. Techniques for removing sulfur oxide compounds include extraction, distillation, and adsorption processing steps. However, no efficient method has been proposed for the final disposal of sulfoxide and sulfone.

  Some teachings of the prior art deal with desulfurization processes that integrate hydrodesulfurization and oxidative desulfurization processes. For example, U.S. Patent No. 6,057,096, incorporated herein by reference, discloses an integrated process in which a hydrocarbon feed is first contacted with a hydrodesulfurization catalyst in a hydrodesulfurization reaction zone to reduce the sulfur content to a low sulfur level. ing. The hydrocarbon stream obtained from hydrodesulfurization is then sent in its entirety to an oxidation zone containing an oxidant, where residual sulfur is converted to sulfur oxide compounds under mild conditions. After decomposing the residual oxidant, the resulting sulfur oxide compound is extracted with a solvent to obtain a stream containing the sulfur oxide compound and a hydrocarbon oil stream having a reduced concentration of the sulfur oxide compound. The final stage adsorption is carried out in the latter hydrocarbon oil stream to reach an ultra-low sulfur level. However, this document does not give any teaching on the final disposal method of sulfur oxide compounds.

  In US Pat. No. 6,057,031, incorporated herein by reference, a stream containing hydrocarbon oil and a recycle stream containing a sulfur oxide compound are contacted with a hydrodesulfurization catalyst in a hydrodesulfurization reaction zone to produce low levels of sulfur. A process for desulfurization of hydrocarbon-based oils is disclosed. The resulting hydrocarbon stream is subsequently contacted in its entirety with an oxidizing agent in the oxidation reaction zone to convert residual sulfur compounds to sulfur oxide compounds. After decomposing the residual oxidant, the sulfur oxide compound is removed, resulting in a stream containing the sulfur oxide compound and a hydrocarbon oil stream having a reduced concentration of the sulfur oxide compound. To increase hydrocarbon recovery from the process, at least a portion of the sulfur oxide compound is returned to the hydrodesulfurization reaction zone and recycled. However, since some of the produced sulfone compounds are reduced back to the original sulfur compounds, the sulfur disposal problem remains unsolved.

  U.S. Patent No. 6,057,097, incorporated herein by reference, discloses a process for producing a distillate fuel having a lower sulfur level than the distillate feed stream. The distillate feed stream is first fractionated into a light fraction containing only about 50-100 ppmw sulfur and a heavy fraction. The light fraction is then sent to the hydrodesulfurization reaction zone where substantially all the sulfur contained therein is removed. Finally, the desulfurized light fraction is blended with half of the heavy fraction to produce a low sulfur distillate fuel. However, not all distillate feed streams are recovered to obtain a low sulfur distillate fuel product.

  U.S. Patent No. 6,057,096, incorporated herein by reference, discloses an integrated process in which a hydrocarbon feed is first contacted with a hydrodesulfurization catalyst in a hydrodesulfurization reaction zone to reduce the sulfur level to a low sulfur level. . The resulting hydrocarbon stream is then sent in its entirety to an oxidation zone containing an oxidant, where residual sulfur is converted to sulfur oxide compounds under mild conditions. After decomposing the residual oxidant, the resulting sulfur oxide compound is extracted with a solvent to obtain a stream containing the sulfur oxide compound and a hydrocarbon oil stream having a reduced concentration of the sulfur oxide compound. The final stage adsorption is carried out in a hydrocarbon oil stream to reach an ultra-low sulfur level.

  U.S. Patent No. 6,057,097, incorporated herein by reference, discloses contacting a recycle stream containing a hydrocarbon oil and a sulfur oxide compound with a hydrodesulfurization catalyst in a hydrodesulfurization reaction zone to produce low levels of sulfur. The resulting process for desulfurization of hydrocarbon oils is disclosed. The resulting hydrocarbon stream is subsequently contacted in its entirety with an oxidizing agent in the oxidation reaction zone to convert residual sulfur compounds to sulfur oxide compounds. After decomposing the residual oxidant, the sulfur oxide compound is removed, resulting in a stream containing the sulfur oxide compound and a hydrocarbon oil stream having a reduced concentration of the sulfur oxide compound. In order to recover the hydrocarbon portion of the sulfur oxide compound, at least a portion of the sulfur oxide compound is returned to the hydrodesulfurization reaction zone and recycled.

  In U.S. Patent No. 6,057,096, which is incorporated herein by reference, a two-stage desulfurization process is provided downstream of the hydrotreater. After hydrotreating in the hydrodesulfurization reaction zone, the entire distillate feed stream is sent to the oxidation reaction zone, and the two-phase oxidation of aqueous formic acid-hydrogen peroxide solution results in the oxidation compound corresponding to the thiophene sulfur compound, Converted to sulfone. Part of this sulfone is present in the aqueous oxidation solution at the end of the oxidation reaction and is further removed by a subsequent phase separation step. The oil phase containing residual sulfone is finally treated in a liquid-liquid extraction process. There is no description about the fate of sulfone.

  U.S. Patent No. 6,057,097, incorporated herein by reference, discloses a process for removing sulfur from a hydrocarbon stream. The hydrocarbon stream containing the sulfur compound is sent to an oxidation reaction zone where the organic sulfur compound is oxidized to the corresponding sulfone using an aqueous oxidant. After separating the aqueous oxidant from the hydrocarbon phase, the resulting hydrocarbon stream is sent to a hydrodesulfurization step. The resulting hydrocarbon is substantially reduced in sulfur.

  U.S. Patent No. 6,057,096, incorporated herein by reference, discloses a process for producing a transportation fuel or transportation fuel blend component by reducing the sulfur and / or nitrogen content of the distillate feedstock. The hydrotreated feed is contacted in an oxidation / adsorption zone with an oxygen-containing gas and a titanium-containing mesoporous oxidation catalyst to convert the sulfur compound to the corresponding sulfone that is adsorbed on the catalyst. There is no description about the fate of sulfone.

  U.S. Patent No. 6,057,028, incorporated herein by reference, discloses a process for removing sulfur compounds present in a hydrocarbon stream. Sulfur compounds are first introduced into the enrichment zone and their concentration is increased, for example by complexing with ammonium complexes, adsorption or extraction, and then separated from the sulfur-depleted petroleum feed. Subsequently, selective oxidation of the separated sulfur compounds is carried out in the gas phase using air or oxygen in the presence of a supported catalyst to obtain useful oxygenated products and sulfur deficient hydrocarbons.

U.S. Patent No. 6,057,096, incorporated herein by reference, discloses a process that is effective in removing organosulfur compounds from liquid hydrocarbons. This process relates more specifically to the removal of thiophene and thiophene derivatives from a number of petroleum fractions such as gasoline, diesel fuel, and kerosene. In the first stage of the process, the liquid hydrocarbon is subjected to oxidizing conditions to oxidize at least a portion of the thiophene compound to the sulfone. These sulfones can then be catalytically decomposed to produce hydrocarbons (eg, hydroxybiphenyl) and volatile sulfur compounds (eg, sulfur dioxide). The hydrocarbon cracking products remain in the processing liquid as a useful blend component, but volatile sulfur compounds are easily separated from the processing liquid using well-known techniques such as flash evaporation or distillation.

Various methods using alkaline metals (Li, Na, K), lithium naphthalenide, SmI ₂ -HMPA, or LiAlH ₄ in the presence of nickel compounds for reductive removal of sulfones and reductive cleavage of classical sulfonamides Have been reported (Non-Patent Document 1) and (Non-Patent Document 2). All of these reduction methods are mediated by highly aggressive metal-containing reducing agents. Electrochemical reduction is also used for reductive cleavage of aryl sulfones (Non-Patent Document 3) (ArSO ₂ R) and sulfonamides (Non-Patent Document 4).

  Reductive cleavage of sulfones and sulfonamides using tetraazaalkenes has also been reported. Tetraazaalkenes are neutral organic electron donors and one of a series of reagents recently named “superelectron donor” reagents (Non-Patent Document 5). A more powerful reducing agent was synthesized as bisimidazolidene. However, research on bisimidazolidene has been limited and has only been carried out with model compounds.

US Patent Application Publication No. 13 / 181,043 US Pat. No. 6,174,178 US Pat. No. 6,277,271 US Pat. No. 6,087,544 US Pat. No. 6,174,178 International Publication No. 2002/18518 Pamphlet International Publication No. 2003/014266 Pamphlet International Publication No. 2006/071793 Pamphlet US Patent Application Publication No. 2005 / 0150819A1 US Pat. No. 6,368,495

Jones, Simkins et al. 1998 Prakash, Chacko et al. 2009 Jolivet et al. , Tetrahedron Letters, 43 (44), 7907-7911 2002. Klein et al. , Journal of Electroanalytical Chemistry; 487 (1): 66-71 (2000). Schoenebeck, JASC, 129 (44): 13368-13369 (2007)

The process of the present invention is a method of improving hydrocarbon feedstock by removal of sulfone and sulfoxide,
a. Supplying a hydrocarbon feed to the oxidation reactor, wherein the hydrocarbon feed contains a sulfur-containing compound;
b. The hydrocarbon feed is contacted with an oxidant in the presence of a catalyst under conditions sufficient to selectively oxidize sulfur compounds present in the hydrocarbon feed in an oxidation reactor to produce hydrocarbon and oxidation. Producing a hydrocarbon stream comprising sulfur-containing compounds;
c. Separating the sulfur oxide-containing hydrocarbon stream into an aqueous phase and a non-aqueous oxidizing eluate;
d. The non-aqueous oxidized eluate is recovered and contacted with an electron donor to reduce the sulfone and sulfoxide present in the non-aqueous oxidized eluate , and the reductive cleavage of the carbon-sulfur bond in the sulfone and sulfoxide. Causing and decomposing to produce by-product salts and desulfurized hydrocarbons ; and
e. The method comprising; a salt by-product was isolated, recovering the flow of desulfurized hydrocarbons.

  According to the present invention, the carbon-sulfur bond in the sulfone and sulfoxide remaining after oxidative desulfurization is reductively cleaved.

  Also according to the invention, the use of an electron donor causes reductive cleavage of carbon-sulfur bonds in sulfones and sulfoxides.

Flow chart of the sulfone cracking process of the present invention including the oxidative desulfurization of hydrocarbon feed prior to this process. Flow chart of the sulfone cracking process of the present invention, including oxidative desulfurization and solvent extraction of hydrocarbon feeds prior to the process. Flowchart of the sulfone cracking process of the present invention including oxidative desulfurization, solvent extraction and adsorption of hydrocarbon feeds prior to the process.

  According to the process of the present invention, an oxidized hydrocarbon stream containing oxides of sulfur compounds such as sulfones and sulfoxides is first contacted with an electron donor to decompose the sulfur compounds at elevated temperatures. This process does not require the use of a catalyst.

  The process of the present invention is generally carried out following integrated hydrodesulfurization followed by oxidative desulfurization or oxidative desulfurization. However, as mentioned above, an efficient method for the final disposal of oxidation reaction by-products, i.e. sulfur oxide compounds, has not been disclosed so far. The process of the present invention discloses whether such disposal is carried out using an electron donor.

  In one aspect, the present invention provides a method for improving hydrocarbon feedstocks, particularly hydrocarbon feedstocks containing sulfur-containing compounds. In certain embodiments, the hydrocarbon feed includes nitrogen-containing species that can be oxidized and removed in addition to or instead of sulfur species.

  As shown in FIG. 1 which is one embodiment of the present invention, the sulfone conversion apparatus 10 includes an oxidation reactor 12, a first separation apparatus 16, a sulfone decomposition vessel 19 and a second separation apparatus 22. Hydrocarbon feedstock 11 is introduced into oxidation reactor 12 where hydrocarbon feedstock 11 contacts oxidant 13 in the presence of catalyst 14. In certain embodiments, the catalyst 14 can be regenerated from this process or another process and fed with or in place of the new catalyst.

  The hydrocarbon feedstock 11 can be any petroleum-based hydrocarbon and can include various impurities such as elemental sulfur and / or compounds including sulfur and / or nitrogen. In certain embodiments, the hydrocarbon feed 11 can be a diesel oil having a boiling point of about 36 ° C to 2000 ° C. Alternatively, the hydrocarbon feedstock 11 can have a boiling point of about 80 ° C to about 560 ° C. Preferably, the hydrocarbon feedstock 11 can have a boiling point of about 180 ° C to about 400 ° C. In certain embodiments, the hydrocarbon feedstock 11 can be a solid residue. In certain embodiments, the hydrocarbon feed 11 can include heavy hydrocarbons. As used herein, heavy hydrocarbons refer to hydrocarbons having a boiling point greater than about 360 ° C. and can include aromatic hydrocarbons and naphthalene, as well as alkanes and alkenes. Generally, in certain embodiments, the hydrocarbon feedstock 11 is from a full range of crude oil, overhead crude oil, refinery product stream, refinery steam cracking process product stream, liquefied coal, oil or tar sand. It can be selected from recovered liquid products, bitumen, oil shale, asphaltene, and the like, and mixtures thereof.

  Representative sulfur compounds present in the hydrocarbon feedstock 11 include sulfides, disulfides, and mercaptans, aromatic molecules such as thiophene, benzothiophene, dibenzothiophene, and 4,6-dimethyl-dibenzothiophene. An alkyl dibenzothiophene is mentioned. Aromatic compounds are generally more abundant in high-boiling fractions than are normally present in low-boiling fractions.

  In certain embodiments, hydrocarbon feedstock 11 can include nitrogen-containing compounds, and in certain embodiments, representative compounds include basic and neutral nitrogen compounds such as indole, carbazole, aniline, quinoline, acridine. Etc.

  The oxidation reactor 12 can be operated under milder conditions than those commonly used in conventional diesel hydrodesulfurization processes. More specifically, in certain embodiments, the oxidation reactor 12 is about 20 ° C to about 150 ° C, alternatively about 30 ° C to about 150 ° C, alternatively about 30 ° C to about 90 ° C, or about 90 ° C to about 90 ° C. It can be operated at a temperature of 150 ° C. In certain embodiments, this temperature is preferably about 30 ° C to about 75 ° C, more preferably about 45 ° C to 60 ° C.

The operating pressure of the oxidation reactor 12 can be about 1 to 30 bar, alternatively about 1 to 15 bar, alternatively about 1 to 80 bar, preferably about 2 to 3 bar. The residence time of the hydrocarbon feedstock 11 in the oxidation reactor 12 is about 1 to 180 minutes, alternatively about 15 to 180 minutes, alternatively about 15 to 90 minutes, alternatively about 5 to 60 minutes, alternatively about 30 to 60 minutes, Alternatively, it may be about 60-120 minutes, alternatively about 120-180 minutes, preferably present for a time sufficient to oxidize any sulfur or nitrogen compounds present in the hydrocarbon feed 11. In one embodiment, the residence time of the hydrocarbon feed 11 in the oxidation reactor 12 is about 15 to 45 minutes. In comparison, conventional hydrodesulfurization of diesel-type feedstocks generally undergo severer conditions, for example, temperatures of about 330 ° C. to 380 ° C., pressures of about 50 to 80 kg / cm ² , and liquid space velocity ( LHSV) is performed at about 0.5-2 h ⁻¹ .

  Oxidation reactor 12 provides sufficient contact between hydrocarbon feed 11 and oxidant 13 to oxidize at least a portion of the sulfur and nitrogen containing compounds contained in the reactor in the presence of catalyst 14. Any reactor appropriately configured to ensure Suitable reactors for the oxidation reactor 12 include batch reactors, fixed bed reactors, boiling bed reactors, lift reactors, fluidized bed reactors, slurry bed reactors and the like. Certain sulfur and nitrogen compounds present in the hydrocarbon feed 11 are oxidized in the oxidation reactor 12 to sulfones, sulfoxides and nitric oxide compounds, which can then be removed by separation, extraction and / or adsorption. Examples of nitric oxide compounds include pyridine and pyrrole-based compounds or pyridine-difuran compounds. In many cases, oxidation does not oxidize the nitrogen atom itself, but oxidizes the compound to produce a compound that is easily separated from the rest of the compound.

  Suitable oxidants include air, oxygen, ozone, hydrogen peroxide, organic peroxides, hydroperoxides, organic peracids, peroxo acids, nitrogen oxides, and the like, and combinations thereof. A representative peroxide can be selected from hydrogen peroxide and the like. A representative hydroperoxide can be selected from t-butyl peroxide and the like. A typical organic peracid can be selected from peracetic acid and the like.

  In certain embodiments, such as hydrocarbon feeds having a higher concentration of sulfur than nitrogen, the molar ratio of oxidizer to sulfur present in the hydrocarbon feed is about 1: 1 to 50: 1, preferably about 2 : 1 to 20: 1, more preferably about 4: 1 to 10: 1.

  Hydrocarbon feedstocks with higher concentrations of nitrogen than sulfur, such as South American crude oil, certain African crude oils, certain Russian crude oils, certain Chinese crude oils, and certain intermediate refinery streams (eg coker, pyrolysis, bis In certain other embodiments, such as braking, FCC cycle oil, etc.), the molar ratio of oxidizer to nitrogen present in the hydrocarbon feed is about 1: 1 to 50: 1, preferably about 2: 1. ~ 20: 1, more preferably about 4: 1 to 10: 1.

  The catalyst 14 can include at least one metal oxide having the chemical formula MxOy, where M is a metal selected from groups IVB, VB, or VIB of the periodic table. Certain exemplary catalysts can be homogeneous catalysts including one or more metal oxides. Typical metals include titanium, vanadium, chromium, molybdenum, and tungsten. Certain preferred metals include molybdenum and tungsten oxides.

  The ratio of catalyst to oil is about 0.1% to about 10% by weight, preferably about 0.5% to about 5% by weight. In certain embodiments, this ratio is from about 0.5% to about 2.5% by weight. Alternatively, this ratio is from about 2.5% to about 5% by weight.

  The catalyst present in the oxidation reactor 12 increases the oxidation rate of various sulfur and / or nitrogen containing compounds in the hydrocarbon feed 11 and / or reduces the amount of oxidant required for the oxidation reaction. Thereby completing the reaction and oxidation of the sulfur and nitrogen containing compounds in a shorter time and / or reducing the amount of oxidant required to achieve the oxidation of the sulfur and nitrogen containing compounds. In certain embodiments, the catalyst can be selected for the purpose of oxidizing sulfur-containing compounds. In a preferred embodiment, the catalyst is selected to minimize the oxidation of aromatic hydrocarbons present in the hydrocarbon feed 11.

  The composition of the oxidant by-product will vary depending on the nature of the original oxidant used in the process. For example, in embodiments where the oxidant is hydrogen peroxide, water is produced as a byproduct of the oxidation reaction. In embodiments where the oxidant is an organic peroxide, alcohol is produced as a byproduct of the oxidation reaction. By-products are generally removed in extraction and solvent recovery steps.

  The oxidation eluate 15 generated from the oxidation reactor 12 contains sulfur oxide and nitric oxide compounds, and is discharged from the oxidation reactor 12 and sent to the first separation device 16, where the oxidation eluate 15 is discharged from the water. Separated into phase 17 and non-aqueous oxidation eluent 18 sent to sulfone cracking vessel 19.

  In order to remove the sulfur oxide compound, the non-aqueous oxidation eluent 18 and the electron donor 20 are brought into contact in the sulfone decomposition vessel 19.

  The amount of electron donor 20 used is in the range of about 1 to about 5 molar equivalents, preferably about 1 to about 3 molar equivalents, based on the sulfone content of the raw material. The electron donor 20 must have an oxidation potential to reduce the sulfone and sulfoxide. For example, various electron donors such as bispyridinylidene and bisimidazolidene can be used advantageously, but it is preferable to use a tetraazaalkene that generates radical cations and dications upon oxidation. It is particularly preferred to use bisbenzimidazolidene.

  When the decomposition reaction in the sulfone decomposition vessel 19 is completed, the desulfurization eluate 21 (most of sulfur is removed) leaves the sulfone decomposition vessel 19 and is sent to the second separation device 22 where it is mixed with water. The salt of the reaction by-product is washed and purified. In the second separator 22, the separation is carried out to obtain a discarded water / salt stream 23 and a recovered desulfurized oil 24.

  As shown in FIG. 2, which is another embodiment of the present invention, the sulfone converter 110 includes an oxidation reactor 112, a first separator 116, an extraction vessel 125, a sulfone decomposition vessel 119, and a second separator 122. . Hydrocarbon feedstock 111 is fed to oxidation reactor 112 where hydrocarbon feedstock 111 contacts oxidant 113 in the presence of catalyst 114. In certain embodiments, the catalyst can be regenerated from this process or another process and fed with or in place of the new catalyst. The features of the hydrocarbon feed 111 and oxidation reactor 112 and the operating conditions of the oxidation reactor 112 have been discussed above with respect to the embodiment of FIG.

  When the reaction in the oxidation reactor 112 is completed, an oxidation eluate 115 containing sulfur oxide and a nitric oxide compound is discharged from the oxidation reactor 12 and sent to the first separation device 116.

  In the first separator 116, the oxidized eluate 115 is separated into the aqueous phase 117 and the non-aqueous oxidized eluent 18.

  The non-aqueous oxidized eluate 118 is supplied to the extraction vessel 125 where it is contacted with the flow of extraction solvent 126.

  The extraction solvent 126 can be a polar solvent, and in certain embodiments, the solubility value of Hildebrand can be greater than about 19. In certain embodiments, when selecting a polar solvent for use in the extraction of sulfur oxide and nitrogen containing species, the selection is based in part on solvent density, boiling point, freezing point, viscosity, and surface tension. May be. Typical polar solvents suitable for use in the extraction step include acetone (Hildebrand value 19.7), carbon disulfide (20.5), pyridine (21.7), dimethyl sulfoxide (DMSO) (26.4). ), N-propanol (24.9), ethanol (26.2), n-butyl alcohol (28.7), propylene glycol (30.7), ethylene glycol (34.9), dimethylformamide (DMF) ( 24.7), acetonitrile (30), methanol (29.7) and the like. In certain embodiments, acetonitrile and methanol are preferred due to their low cost, volatility, and polarity. In certain embodiments, the solvent comprising sulfur, nitrogen, or phosphorus preferably has a relatively high volatility to ensure sufficient stripping of the solvent from the hydrocarbon feed.

  In a preferred embodiment, the extraction solvent is non-acidic. The use of acids is generally avoided due to the corrosive nature of the acids and the need to design all equipment specifically for the corrosive environment. Furthermore, acids such as acetic acid can make separation difficult due to the formation of an emulsion.

  The extraction vessel 125 can be operated at a temperature of about 20 ° C to 60 ° C, preferably about 25 ° C to 45 ° C, and even more preferably about 25 ° C to 35 ° C. The extraction vessel 125 can be operated at a pressure of about 1 to 10 bar, preferably about 1 to 5 bar, more preferably about 1 to 2 bar. In certain embodiments, the extraction vessel 125 operates at a pressure of about 2-6 bar.

  The ratio of extraction solvent 126 to non-aqueous oxidizing eluent 118 can be about 1: 3 to 3: 1, preferably about 1: 2 to 2: 1, more preferably about 1: 1. The contact time between the extraction solvent 126 and the non-aqueous oxidizing eluent 118 can be about 1 second to 60 minutes, preferably about 1 second to about 10 minutes. In certain preferred embodiments, the contact time is less than about 15 minutes. In certain embodiments, the extraction vessel 125 includes various means for extending the contact time between the extraction solvent 126 and the non-aqueous oxidizing eluent 118 or for increasing the degree of mixing of the two solvents. Examples of the mixing means include mechanical stirrers, agitators, trays and the like.

  Desulfurized oil 127 and sulfone and sulfoxide stream 128 are generated from extraction vessel 125. In accordance with the inventive process disclosed herein with respect to the method of FIG. 1, desulfurized oil 127 is recovered, but sulfone and sulfoxide stream 128 is sent to sulfone cracking vessel 119 where it is contacted with electron donor 129. To do.

  When the sulfone decomposition in the container 119 is completed, the desulfurization eluate 130 exits the container and is mixed with water and sent to the second separator 122, where reaction by-products are removed together with the salt stream, The resulting water / salt stream 131 is obtained and the recovered desulfurized oil stream 132 is recovered.

  As shown in FIG. 3, which is another embodiment of the present invention, the sulfone conversion apparatus 210 includes an oxidation reactor 212, a first separation apparatus 216, an extraction container 225, an adsorption zone 233, a sulfone decomposition container 219, and a second separation apparatus. 222. Hydrocarbon feedstock 211 is fed to oxidation reactor 212 where feedstock 211 contacts oxidant 213 in the presence of catalyst 214.

  After completion of the reaction in the oxidation reactor 212, an oxidation eluate 215 containing sulfur oxide and a nitric oxide compound is discharged from the oxidation reactor 212 and sent to the first separation device 216. In the first separation device 216, the oxidized eluate 215 is separated into the discharged aqueous phase 217 and the non-aqueous oxidized eluent 218 sent to the extraction vessel 225.

  After completion of extraction in the extraction vessel 225, the extracted eluate 235 is sent to the adsorption zone 233 according to the method disclosed above with respect to FIG. After contacting the appropriate adsorbent material for an appropriate residence time, desulfurized oil 236 is produced and recovered and sulfone and sulfoxide stream 237 is removed.

  Typical adsorbents include activated carbon, silica gel, alumina, natural clay and other inorganic adsorbents. Also included are polar polymers applied to silica gel, activated carbon and alumina.

  The adsorption zone 233 can be a column operated at a temperature of about 20 ° C to 60 ° C, preferably about 25 ° C to 40 ° C, and even more preferably about 25 ° C to 35 ° C. In certain embodiments, the adsorption zone can be operated at a temperature of about 10 ° C to 40 ° C, alternatively about 35 ° C to 75 ° C. In certain embodiments, the adsorption zone can be operated at temperatures above about 20 ° C or alternatively at temperatures below about 60 ° C. The adsorption zone can be operated at a pressure of up to about 15 bar, preferably up to about 10 bar, and even more preferably about 1-2 bar. In certain embodiments, the adsorption zone can be operated at a pressure of about 2-5 bar. In an exemplary embodiment, the adsorption zone can be operated at a temperature of about 25 ° C. to 35 ° C. and a pressure of about 1-2 bar. The weight ratio of stripped oil stream to adsorbent is about 1: 1 to about 20: 1, alternatively about 5: 1 to about 15: 1. In another embodiment, the ratio is from about 7: 1 to about 13: 1, with a typical ratio being about 10: 1.

  The sulfone and sulfoxide stream 238 discharged from the extraction vessel 225 is sent to the sulfone cracking vessel 219 where it is contacted with the electron donor 239 under the same method and under the same conditions as described above for the methods of FIGS. .

  When the sulfone decomposition in the container 219 is completed, the desulfurization eluate 240 (most of sulfur is removed) exits the sulfone decomposition container 219 and is sent to the second separation device 222 where it is mixed with water. The reaction by-product salt is washed. In the second separator 222, the separation is performed to obtain a water / salt stream 241 to be discarded and a desulfurized oil stream 242 to be recovered.

A hydrogenated straight run diesel oil containing 500 ppmw elemental sulfur, 0.28 wt% organic sulfur and having a density of 0.85 KG / L was oxidatively desulfurized according to the process of FIG. The reaction conditions were as follows.
Catalyst: Molybdenum-based Mo (VI)
Reaction time: 30 minutes Temperature: 80 ° C
Pressure: 1 kg / cm ²

During extraction, 93 kg of bisimidazolylidene was used as the electron donor. The extraction was carried out at 110 ° C., 1 kg / cm ² pressure and 0.1 h ⁻¹ LHSV.

  The material balances of the oxidation process and the extraction process are shown in Tables 1 and 2, respectively. The desulfurized diesel oil contained 40 ppmw sulfur.

ODS (oxidative desulfurization)

Extraction

Sulfone decomposition

  While certain representative embodiments and details have been shown for purposes of illustrating the invention, various modifications may be made to the method disclosed herein without departing from the scope of the invention as defined in the claims. Also good.

Claims (20)

A method for improving a hydrocarbon feedstock by removing sulfone and sulfoxide from the hydrocarbon feedstock, comprising:
a. Supplying a hydrocarbon feed to the oxidation reactor, wherein the hydrocarbon feed contains a sulfur-containing compound;
b. The hydrocarbon feed is contacted with an oxidant in the presence of a catalyst under conditions sufficient to selectively oxidize sulfur compounds present in the hydrocarbon feed in an oxidation reactor to produce hydrocarbon and oxidation. Producing a hydrocarbon stream comprising sulfur-containing compounds;
c. Separating the sulfur oxide-containing hydrocarbon stream into an aqueous phase and a non-aqueous oxidizing eluate;
d. The non-aqueous oxidized eluate is recovered and contacted with an electron donor to reduce the sulfone and sulfoxide present in the non-aqueous oxidized eluate, and the reductive cleavage of the carbon-sulfur bond in the sulfone and sulfoxide. Causing and decomposing to produce by-product salts and desulfurized hydrocarbons;
e. Separating the by-product salts and recovering the desulfurized hydrocarbon stream. The process according to claim 1, wherein 1 to 5 molar equivalents of an electron donor are used based on the sulfone and sulfoxide content of the raw material. The method according to claim 2, wherein 1 to 3 molar equivalents of an electron donor are used. The method according to claim 1, wherein the decomposition is performed at a temperature of 100 to 300C. The method according to claim 4, wherein the decomposition is performed at 100 to 200 ° C. 5. The method according to claim 5, wherein the decomposition is performed at 100 to 150 ° C. The method according to claim 1, wherein the decomposition is performed at a pressure of 3 to 30 kg / cm ² . The method according to claim ¹ , wherein the decomposition is performed at 0.05 to 4.0 h ⁻¹ . The method of claim 1, wherein the electron donor has an oxidation potential sufficient to effect reductive cleavage of the sulfone and sulfoxide. The method according to claim 9, wherein the electron donor is a tetraazaalkene. The method according to claim 10, wherein the tetraazaalkene is bisimidazolylidene. The method according to claim 1, wherein the hydrocarbon feedstock is crude oil, oil, shale oil, coal liquid, intermediate essential oil product, and a distillation fraction thereof. The method of claim 9, wherein the electron donor has a half potential of at least -1.2V in dimethylformamide when referenced to a saturated calomel electrode. The method according to claim 12, wherein the hydrocarbon raw material boils in a range of 36 to 2000 ° C. The method according to claim 1, wherein after step c, the non-aqueous oxidized eluate is extracted with a solvent and then treated. The method of claim 15, wherein the solvent is a polar solvent. The method according to claim 15, wherein the extraction is performed at 20-60 ° C. and a pressure of 1-10 bar. The method according to claim 15, wherein after the extraction step, the extracted eluate is subjected to an adsorption treatment. The method according to claim 18, wherein the adsorbent for the adsorption treatment is selected from the group consisting of activated carbon, silica gel, alumina, natural clay, silica gel coated with a polar polymer, activated carbon and alumina. The method according to claim 18, wherein the adsorption treatment is operated at 20-60 ° C. and a pressure of 1-15 bar.

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