JP4304340B2 - Catalyst for production of alcohol, production method and apparatus thereof - Google Patents

Description

   The present invention relates to a method for producing alcohols by direct oxidation of lower hydrocarbons, a catalyst used therefor, and a production apparatus therefor.

  Alcohols are important basic chemical substances and are used in a wide range of fields such as fuels and chemical raw materials. In particular, methanol will be described in detail, which is particularly demanded and considered the most important. Methanol has a worldwide production capacity of 30 million tons annually in 1995, and is expected to become a fuel for fuel cells in the future. In addition, dimethyl ether, which is a low-pollution diesel fuel, is produced by a dehydration reaction using an acid catalyst, and methanol is reacted with carbon monoxide by a Monsanto process using a rhodium complex to produce acetic acid which is industrially highly demanded.

Currently, the main production methods of methanol are as follows. A lower hydrocarbon represented by methane is partially oxidized or steam reformed to obtain a synthesis gas (H ₂ + CO), and its component ratio is adjusted appropriately to obtain a raw material gas (H ₂ + CO + CO ₂ ), which is then reacted. A method of contacting a catalyst mainly composed of copper and zinc at a temperature of 200 to 300 ° C. and 20 to 100 atm is common (see, for example, Non-Patent Document 1).

As an ideal reaction for alcohol synthesis, there is a reaction in which a saturated hydrocarbon is directly converted to an alcohol (such as methanol) by partial oxidation or selective oxidation reaction, which is represented by the following chemical formula as exemplified by methane, propane and the like.
(1) CH ₄ + 1 / 2O ₂ → CH ₃ OH
(2) C ₃ H ₈ + 1 / 2O ₂ → CH ₃ OH + C ₂ H ₄
(3) C ₃ H ₈ + 1 / 2O ₂ → (n−, iso−) C ₃ H ₇ OH
(1) is a reaction to obtain methanol directly from methane by oxidative reaction, (2) is a reaction to obtain methanol from propane and ethylene which is an industrially important chemical raw material, and (3) is a reaction to obtain propanol from propane. is there.
However, the decisive catalyst suitable for the direct synthesis of methanol from methane shown in (1) above, in particular, has not yet been found in spite of active research and development, and is a very difficult reaction. Has been.

“Organic Process Industry” by Tateaki Yajima, Atsushi Fujimoto, Dai Nippon Books, 2: “Chemical Process”, Chemical Engineering Society, Tokyo Chemical Doujin)

  This invention is made | formed in view of the above-mentioned actual condition in a prior art. That is, an object of the present invention is to provide a method for producing alcohols by a one-step reaction using hydrocarbons and molecular oxygen as raw materials, to provide a catalyst suitable for the reaction, and a reactor suitable for the reaction Is to provide.

  As a result of intensive studies on the reaction of synthesizing alcohols in a single step by reacting lower hydrocarbons with molecular oxygen, the present inventors have found that inorganic complexes of titanium oxide and other inorganic substances are alcohols. Useful as a catalyst for production, and a flow reactor having a structure in which the product-containing gas after contact with the catalyst stays in a space layer maintained at the reaction temperature for a certain period of time is useful as an alcohol production device. As a result, the present invention has been completed.

That is, the alcohol production method of the present invention is characterized in that hydrocarbons and molecular oxygen are brought into contact with an inorganic composite catalyst containing a titanium compound.
The titanium compound is preferably obtained from a precursor selected from titanium chloride, titanium tetraalkoxide and a titanium complex.
Further, the catalyst for producing alcohols by direct oxidation of hydrocarbons according to the present invention is characterized by comprising an inorganic complex of a titanium compound and an inorganic compound.
Furthermore, the alcohol production apparatus of the present invention is a flow-through alcohol production apparatus for producing an alcohol by reacting a hydrocarbon and molecular oxygen in a gas phase, and includes an inorganic composite catalyst packed layer containing a titanium compound and a catalyst thereof A space layer in which the gas after contact stays for a long time is provided, and the space layer is a reaction tube or a reaction vessel kept at a reaction temperature or a temperature in the vicinity thereof.

  In the present invention, alcohols are directly obtained by a gas phase reaction between hydrocarbon and oxygen, and high demand alcohols such as methanol can be easily produced at low cost.

  In the present invention, alcohols are produced from hydrocarbons and molecular oxygen by a one-step gas phase reaction in the presence of an inorganic composite catalyst containing a titanium compound. The inorganic composite catalyst containing a titanium compound used in the present invention is a substance in which titanium or a compound thereof and an inorganic substance are chemically or physically combined. A particularly preferable substance as titanium or a compound thereof is titanium oxide. Examples of preferable inorganic substances include, but are not limited to, metal compounds, carbon materials, silicon compounds, zeolitic compounds, and mesoporous substances.

Illustrating the inorganic substance in more detail, examples of the metal compound include lithium, sodium, potassium, rubidium, cesium, magnesium, calcium, strontium, barium, scandium, yttrium, titanium, zirconium, vanadium, niobium, tantalum, chromium, molybdenum, Tungsten, manganese, technetium, rhenium, iron, ruthenium, osmium, cobalt, rhodium, iridium, nickel, palladium, platinum, copper, silver, gold, zinc, cadmium, mercury, aluminum, gallium, indium, thulium, germanium, tin, Examples thereof include lead, lanthanum, cerium, praseodymium, samarium, europium oxide, chloride, carbonate, sulfate, nitrate or sulfide. Among these, magnesium, calcium, strontium, barium, titanium, zirconium, aluminum, niobium, zinc, cerium, lanthanum oxide, and carbonate can be preferably used. For example, any crystal structure can be used as long as it has various crystal structures such as an alpha type and a gamma type even with the same atomic composition such as aluminum oxide (chemical formula: Al ₂ O ₃ ). These compounds may be composite compounds containing two or more metal elements.

Examples of the carbon material include activated carbon, graphite, fullerene, carbon nanotube, and diamond. Examples of the silicon compound include silicon dioxide, silica gel, silicon nitride, silicon carbide, and silicalite. Zeolite compounds include A type, X type, Y type, mordenite, beta, ZSM-5, ZSM-11, AlPO ^- n, SAPO ^- n (n is a positive integer), etc. Examples of the abbreviations commonly used in scientific and technical literature include MCM-41, SBA-15, and FSM-16, but are not limited thereto.

  Known methods are used to prepare these inorganic composites, and preferred methods include impregnation method, sol-gel method, vapor phase deposition method, liquid phase adsorption method and the like, but are not limited thereto. Absent. This will be described in more detail using a particularly preferred impregnation method as a simple and safe method. As a titanium compound, for example, titanium tetraisopropoxide which is a kind of titanium tetraalkoxide, titanium compound which is a precursor of titanium oxide such as titanium peroxocitrate ammonium which is a kind of titanium complex or titanium chloride is dissolved in a solvent, The inorganic carrier powder or pellets in the carrier are dispersed in this solution and stirred sufficiently, and the solvent is removed by a method such as reduced pressure or heating to bond the inorganic carrier and the titanium compound. As this solvent, an appropriate solvent having high affinity with an inorganic carrier is used so that the compound can be easily dissolved according to the type of titanium compound. Examples thereof include water, alcohols, ethers, esters. And petroleum solvents. In addition, the inorganic carrier may be subjected to a known pretreatment suitable for the loading method used. Examples of pretreatment include, but are not limited to, heating, drying, gas treatment and the like. In addition, the carbon material can be used by changing the surface characteristics by a known treatment method such as oxygen treatment or steam treatment, if necessary, but it is not essential to perform these pretreatments.

  Next, after the titanium compound is supported, it is preferable to apply energy to the titanium compound from the outside such as heat, electromagnetic waves, radiation, or the like, or add a reactive agent to finally change the state to an oxide state. As a method for applying energy such as heat, electromagnetic waves, and radiation from the outside, a known method can be used. For example, as a safe and easy method, heating using a furnace such as an electric furnace, gas furnace, image furnace, infrared irradiation, visible light irradiation, ultraviolet irradiation, microwave irradiation, X-ray irradiation, laser irradiation Examples include, but are not limited to, electron beam irradiation, alpha ray irradiation, beta ray irradiation, and gamma ray irradiation. In addition, the wavelengths of light such as infrared rays, ultraviolet rays, and microwaves, and electromagnetic waves are not limited.

  The atmosphere for decomposing the precursor is preferably air, oxygen, nitrogen, argon, helium, carbon dioxide, carbon monoxide, water vapor, or a mixed gas thereof, but is not limited thereto. The total amount of heat, electromagnetic wave, and radiation energy applied at that time is desirably an amount sufficient to decompose most of the precursor into titanium oxide. When heat is selected as the external energy, the heating temperature is not particularly limited, but a preferable temperature is 100 to 1500 ° C, more preferably 300 to 800 ° C. The heating time is preferably 1 second to 10 days, more preferably 10 seconds to 10 hours.

  Examples of the reactant include acidic substances such as hydrochloric acid, nitric acid and sulfuric acid, and basic substances such as sodium hydroxide, aqueous ammonia and sodium carbonate, but use an appropriate amount of a substance suitable for decomposing the titanium precursor to be used. Is preferred. When using a reactive agent, it is preferable to remove the reactive agent by a method such as heating or washing after completion of the reaction.

  The raw material gas used in the process for producing alcohols in the present invention needs to contain hydrocarbon and molecular oxygen as essential components. The hydrocarbon is preferably selected from lower saturated hydrocarbons and lower unsaturated hydrocarbons, specifically methane, ethane, propane, n-butane, isobutane, ethylene, propylene, 1-butene, 2-butene. , One or more selected from isobutene, butadiene, and acetylene are used. As the molecular oxygen, oxygen-containing gas such as pure oxygen or air is used. Furthermore, from the viewpoint of safety such as prevention of explosion due to runaway of oxidation reaction, etc., and from the viewpoint of heat medium etc. for mitigating heat generation during reaction and removing it quickly, inert diluent gas should be mixed as necessary. Is preferred. Examples of the dilution gas include nitrogen, helium, argon, neon, krypton, xenon, radon, carbon dioxide, carbon monoxide, and water vapor. These gases are not necessarily used alone, and two or more kinds may be mixed and used.

  In the present invention, as a reaction apparatus for producing alcohols by gas phase reaction of hydrocarbon and molecular oxygen, a known reaction suitable for using a solid catalyst such as a flow type or a batch type, or a powder catalyst is usually used. Although the format can be applied, it is preferable to use a flow reactor. The material of the reactor is preferably made of an inert material having high heat resistance such as quartz or stainless steel, and even if it has been treated with a known inert material such as coating. good. In the present invention, a space layer in which a gas after contact with the catalyst stays for a long time is provided after the inorganic composite catalyst packed layer containing a titanium compound, and the space layer is kept at a reaction temperature or a temperature in the vicinity thereof. It consists of a reaction tube or reaction tank.

  In order to prevent the catalyst from moving and flowing out, it is desirable that the catalyst packed bed and the space layer be partitioned by an inert material and shape partition without interfering with gas flow. The space layer is a layer in which the mixed product gas after contact with the catalyst stays for a long time, and is kept at the reaction temperature or a temperature close thereto, preferably 100 to 1200 ° C., more preferably 200 to 800 ° C. Is preferred. The temperature difference between the catalyst layer and the rear space layer is not particularly limited, but a range of (catalyst layer temperature) − (space layer temperature) is preferably −200 to 200 ° C., particularly preferably −50 to 50. It is in the range of ° C. Further, the preferable volume of the rear space layer is a volume in which the mixed product gas after contact with the catalyst can be heated for a long time, and the value obtained by dividing the space layer volume by the raw material gas flow rate (gas residence time) is particularly limited. Although it is not, it is preferable that the time is 5 seconds to 60 minutes or more, and a particularly preferable time is 10 seconds to 10 minutes.

  The reaction apparatus of the present invention will be described with reference to the drawings. FIG. 1 is a conceptual diagram for further clarifying the structure of the tubular flow reactor. The supply gas indicated by (A) first comes into contact with the catalyst in the catalyst packed bed indicated by (B), and then passes through a partition having a material and shape that does not obstruct the gas flow indicated by (C), The rear space layer indicated by (D) is reached. The entire tube is maintained at or near the reaction temperature using a heater for heating indicated by (E). After being retained for a long time here, the gas containing the product, unreacted raw materials, etc. is discharged out of the pipe by (F). (G) is a tubular reaction tube.

  In addition, a fluidized bed catalytic reactor, which is one of flow-type reactors, can also be preferably used for this reaction. In this case as well, similarly, the gas in contact with the catalyst is at or near the reaction temperature, preferably It is desirable that the temperature is kept at 100 to 1000 ° C, more preferably 150 to 650 ° C. In this case, the volume obtained by subtracting the catalyst volume provided for the reaction from the internal volume of the reactor becomes the space layer volume, and the value obtained by dividing the space layer volume by the raw material gas flow rate (gas residence time) is not particularly limited. Like the above fixed bed apparatus, it is preferable to have a structure in which it stays for a long time, preferably 5 seconds to 60 minutes, or more, particularly preferably 10 seconds to 10 minutes.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples.

(Preparation of catalyst)
Titanium peroxocitrate ammonium tetrahydrate (chemical formula: (NH ₄ ) ₄ [Ti ₂ (C ₆ H ₄ O ₇ ) ₂ (O ₂ ) ₂ ] · 4H ₂ O or (NH ₄ ) ₈ [Ti ₄ (C ₆ H ₄ O ₇ ) ₄ (O ₂ ) ₄ ] · 8H ₂ O) (trade name: Tasfine, manufactured by Furuuchi Chemical Co., Ltd.) 0.6 g was dissolved in 50 mL of distilled water to obtain a uniform solution. Silicon dioxide powder (Caractect Q-30, manufactured by Fuji Silysia Chemical Ltd., physical property values (values described in the catalog)): surface area 100 m ² / g, average pore diameter 30 nm, pore volume 1.0 mL / g, particles 9.8 g (diameter 75 to 500 μm) was dispersed to form a slurry. After sufficiently stirring this, it was dried under reduced pressure at 80 ° C. to remove water, and a powder containing a titanium precursor composed of a titanium compound and silicon dioxide was produced.
Next, the produced powder was fired in air at 600 ° C. for 3 hours to obtain an inorganic composite powder. The obtained composite powder was composed of a weight composition ratio of 2% titanium oxide and 98% silicon dioxide.

(Manufacture of alcohols using propane and oxygen as raw materials)
1.0 g of the composite powder (sample A) obtained in Example 1 was used as a catalyst, which was physically mixed with 3.0 g of quartz sand and filled into a quartz reaction tube. This reaction tube has a catalyst packed bed followed by a 25 mL space. The temperature was raised to 330 ° C. while allowing helium to flow through the reaction tube, and after confirming the stability of the temperature, helium was mixed with propane at 10 mL / min, oxygen at 5 mL / min, and helium at 5 mL / min (for each meter). The reaction was started by switching to 20 mL / minute). At that time, the time for the gas after the reaction to stay in the space behind the catalyst layer was 1.25 minutes. The reaction pressure was 3.5 atmospheres (pressure gauge reading). After 25 minutes, it was confirmed that the temperature and pressure were stable at 330 ° C., and the product was analyzed using an online gas chromatograph.
As a result, the conversion rate of propane was 19.4%, the yield of alcohols (total of methanol, ethanol, n-propanol and isopropanol) was 2.3%, and the yield of methanol was 1.9%, The methanol selectivity was 9.7%. The main by-products were CO, CO ₂ , aldehydes, ketones, and hydrocarbons, and the hydrocarbons contained ethylene. As a result, it became clear that alcohols represented by methanol can be synthesized by oxidation of propane with molecular oxygen using this catalyst.

(Manufacture of alcohols using methane and oxygen as raw materials)
1.0 g of the composite powder (sample A) obtained in Example 1 was used as a catalyst, which was physically mixed with 3.0 g of quartz sand and filled into a quartz reaction tube. This reaction tube is provided with a catalyst packed bed followed by a 25 mL space. The reaction temperature was raised to 500 ° C. while helium was circulated in the reaction tube, and after confirming the stability of the temperature, a mixed gas of methane 10 mL / min, oxygen 5 mL / min, and helium 5 mL / min as a hydrocarbon (total The reaction was switched to 20 mL / min). In this case, the time for the gas after the reaction to stay in the space behind the catalyst layer was 1.25 minutes. The reaction pressure was 3.5 atmospheres (pressure gauge reading). After 25 minutes, it was confirmed that the temperature and pressure were stable at 500 ° C., and the product was analyzed using an online gas chromatograph.
As a result, the conversion rate of methane was 12.9%, the yield of methanol was 0.3%, and the selectivity of methanol was 2.3%. The main by-products were CO, CO ₂ and hydrocarbons. This revealed that methanol can be synthesized by oxidation of methane with molecular oxygen using this catalyst.
(Comparative Example 1)

The reactor used in the reaction of Example 2 has a structure in which a space of 25 mL is provided behind the catalyst packed bed and is maintained at substantially the same temperature as the reaction temperature, and the gas in contact with the catalyst stays in the reaction tube for 1.25 minutes. However, the space behind it was filled with quartz sand, and most of the space was closed so as not to disturb the gas flow, and the gas residence time in the space layer was made less than 3 seconds. In the apparatus, a mixture of 1.0 g of the composite powder (sample A) obtained in Example 1 and 3.0 g of inert quartz sand was used as a catalyst, the supply gas was propane 10 mL / min, oxygen 5 mL / min, and helium. The reaction was performed at 5 mL / min, a reaction temperature of 335 ° C., and a reaction pressure of 3.5 atm. The obtained product was analyzed in the same manner as in Example 2. As a result, the propylene conversion was 0.4%, the yield of alcohols (total of methanol, ethanol, n-propanol, and isopropanol) was 0%, and the selectivity for alcohols was 0%.
From this, it was confirmed that the reaction tube having the rear space layer in which the reaction gas is retained for a relatively long time of 1 minute or more is effective as an alcohol production apparatus.

  INDUSTRIAL APPLICABILITY The present invention is a novel one-step synthesis method for alcohols using hydrocarbon as a raw material and is useful as a simple industrial production method.

It is a schematic block diagram which shows an example of the alcohol manufacturing apparatus of this invention.

Explanation of symbols

A ... Supply gas B ... Catalyst packed bed C ... Partition D ... Spatial layer E ... Heating heater F ... Gas containing product G ... Reaction tube

Claims (2)

  A flow-type alcohol production apparatus for producing an alcohol by reacting a hydrocarbon with molecular oxygen in a gas phase, an inorganic composite catalyst packed layer containing a titanium compound, and a space layer in which a gas after contacting the catalyst stays for a long time An alcohol production apparatus comprising: a reaction tube or a reaction vessel in which the space layer is kept at a reaction temperature or a temperature in the vicinity thereof.   2. The alcohol production apparatus according to claim 1, wherein the catalyst packed layer and the space layer are partitioned by a partition having a material and a shape that do not hinder gas flow.

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