JP5225026B2 - Copper catalyst regeneration method - Google Patents

Description

  The present invention relates to a method for regenerating a solid catalyst that can efficiently regenerate a solid copper catalyst deactivated by sintering (reduction in catalyst surface area accompanying crystallization of a copper catalyst) or adsorption of a sulfur-containing catalyst poison component.

  Solid copper catalysts are widely used in various reactions such as the production of carbonyl compounds (aldehydes, ketones, etc.) by dehydrogenation of alcohols, and the production of alcohols by hydrogenation of carbonyl compounds. One of the catalysts.

  Among them, aldehyde is an industrially important compound as a synthetic intermediate for various organic compounds, and establishment of an industrial synthesis method from alcohol is desired. In addition, aldehyde production using alcohol has attracted attention in recent years because bioalcohol (alcohol obtained by biomass fermentation such as bioethanol) that is a raw material for removing petroleum can be used. However, in aldehyde production using alcohol, there are problems such as insufficient conversion of alcohol and aldehyde selectivity, and easy deactivation of the copper catalyst used. Therefore, industrially, aldehyde production using alcohol as a raw material has hardly been carried out, and acetaldehyde is currently produced by a so-called Wacker method using ethylene as a raw material.

  Further, when a solid copper catalyst is used for aldehyde production by dehydrogenation of alcohol, the catalyst temperature needs to be kept at a high temperature of about 200 ° C. to 300 ° C. in order to make the equilibrium advantageous for the aldehyde side. However, when exposed to such a high temperature in the reduced state, the crystal grains of copper metal as an active species grow and the effective surface area decreases (so-called sintering phenomenon occurs), and the reaction activity gradually decreases. The problem that the catalyst life is extremely short is known.

  Furthermore, when aldehydes are produced using bioethanol, sulfides such as dimethyl sulfide that are inevitably contained in bioethanol are strongly adsorbed to metallic copper, which is a catalytically active species, and act as a catalyst poison. However, the problem of reducing the catalytic activity is also known.

  Various methods have been known as regeneration methods for the deactivated catalyst. However, these methods generally remove organic components (substrate, main or by-products, decomposition products or polymers thereof) adhering to the catalyst surface. There are few known methods of regenerating a catalyst whose activity has been reduced by sintering or sulfur-based catalyst poison components, which are removal (removal by a method such as combustion or cleaning).

For example, in Japanese Patent Laid-Open No. 9-75734 (Patent Document 1), a copper-containing catalyst deactivated during reaction use is subjected to pretreatment of a hydrogen-containing gas, oxidation treatment with an oxygen-containing gas, and treatment with a reducing gas. A method for regenerating a catalyst is disclosed. Further, in Patent Document 1, pretreatment is for facilitating desorption of organic substances adhering to the catalyst, and the regeneration method of Patent Document 1 is a crystal growth of a catalyst component due to a thermal burden or a new one. It is described that it is insufficient for the decrease in activity associated with the formation of the compound. Japanese Patent Laid-Open No. 2000-93800 (Patent Document 2) discloses that the oil content of a deactivated catalyst is washed with a solvent, then the solvent remaining in the catalyst is removed, and the obtained catalyst is oxidized with an oxygen-containing gas. Further, a method for regenerating a hydrogenation catalyst in which the obtained catalyst is reduced and activated is disclosed. Patent Document 2 discloses that the step of removing the oil suppresses heat generation due to the combustion of the oil in the oxidation step, and reduces the sintering of copper or its oxide as the active site. However, Patent Document 2 does not teach any regeneration of a catalyst in which crystals are grown by sintering.
JP-A-9-75734 (Claim 1, paragraph numbers [0010] [0014]) JP 2000-93800 A (Claim 1, paragraph number [0009])

  Accordingly, an object of the present invention is to provide a method for regenerating a copper catalyst that can efficiently regenerate a solid copper catalyst deactivated by sintering (reduction of the catalyst surface area accompanying crystallization of the copper catalyst) or adsorption of a sulfur-containing catalyst poison component. It is to provide.

  Another object of the present invention is to provide a copper catalyst regeneration method that can prolong the life of the catalyst, improve the conversion rate of raw alcohol and the yield of aldehyde, and can be used for industrial aldehyde production. .

  As a result of intensive studies to achieve the above-mentioned problems, the present inventors have found that when oxidized with an oxygen-containing gas and reduced with a hydrogen-containing gas, sintering (reduction in the surface area of the catalyst accompanying crystallization of the copper catalyst) or sulfur-containing catalyst It has been found that even a solid copper catalyst deactivated by adsorption of poisonous components can be effectively regenerated, and the present invention has been completed.

  That is, the regeneration method of the present invention is a method for regenerating a deactivated copper catalyst in which a solid copper catalyst deactivated by sintering or adsorption of a sulfur-containing catalyst poison component is oxidized with an oxygen-containing gas and further reduced with a hydrogen-containing gas. It is. In the regeneration method, the copper catalyst deactivated by sintering at high temperatures and in a reducing atmosphere or by adsorption of sulfide compounds may be subjected to oxidation with an oxygen-containing gas. Further, the copper catalyst deactivated in the process of producing aldehyde by dehydrogenation of alcohol may be subjected to oxidation with an oxygen-containing gas.

  In the present invention, the copper catalyst deactivated in the aldehyde production process by dehydrogenation of alcohol is subjected to oxidation with an oxygen-containing gas without removing the oil with a solvent or pretreating with a hydrogen-containing gas. You may reduce | restore in a gaseous phase with containing gas. Alternatively, the deactivated copper catalyst may be oxidized with an oxygen-containing gas at a temperature of 200 to 500 ° C. and reduced with a hydrogen-containing gas at a temperature of 100 to 200 ° C.

  The deactivated copper catalyst may be a copper catalyst obtained by dehydrogenating alcohol in the presence of a solid copper catalyst, and the solid copper catalyst used for dehydrogenation was composed of silicon oxide. The support may be a solid copper catalyst obtained by reduction activation treatment of a precursor on which a copper compound capable of generating metallic copper by reduction and an alkali metal and / or alkaline earth metal promoter is supported.

  In the present invention, the deactivated solid copper catalyst is oxidized with an oxygen-containing gas and reduced with a hydrogen-containing gas, so even a catalyst deactivated by sintering or adsorption of a sulfur-containing catalyst poison component can be efficiently regenerated. can do. Therefore, the life of the catalyst can be extended. Moreover, the conversion rate of raw material alcohol and the yield of aldehyde can also be improved, and it is useful for industrial aldehyde production.

[Solid copper catalyst]
The solid copper catalyst is not particularly limited as long as it contains copper as an active species, and a solid copper catalyst used for various reactions can be used. Usually, a catalyst used for dehydrogenation or hydrogenation reaction, For example, a solid copper catalyst for synthesizing a carbonyl compound (aldehyde, ketone, etc.) by dehydrogenation of an alcohol, a solid copper catalyst for synthesizing an alcohol by hydrogenation of a carbonyl compound, and the like can be mentioned.

  Copper as the active species may be in any form (or state) having an activity of converting alcohol to aldehyde, and may be metal copper (simple substance), copper compound (oxide, hydroxide, copper salt (copper sulfate, phosphoric acid). Inorganic acid salts such as copper, copper nitrate and copper carbonate; organic acid salts such as copper salt of carboxylic acid)) and the like. The solid catalyst may contain at least one selected from such copper simple substance and copper compound. Copper as the active species is preferably in the form of metallic copper. Copper may be used as it is in the form of metallic copper or a copper compound, or may be used in a form supported on a carrier.

  In addition, copper as an active species should just act as a main catalyst of a solid catalyst, and may be used in combination with a promoter or the like. The solid catalyst may have a form in which both copper and a cocatalyst are supported on a carrier, or a cocatalyst may be used as a carrier, and the copper catalyst may be supported on the cocatalyst.

  Examples of the cocatalyst to be combined with copper include various metals or metal compounds other than copper. Examples of the metal element contained in the promoter include alkali metals (Li, K, Na, etc.), alkaline earth metals (Mg, Ca, Ba, etc.), periodic table group 4 metals (Ti, Zr, etc.), Group 5 metal (V, etc.), Group 6 metal (Cr, Mo, W, etc.), Group 7 metal (Mn, etc.) Group 8 metal (Fe, Ru, etc.), Group 9 metal (Co, Rh, etc.) Group 10 metals (Ni, Pd, Pt, etc.), Group 11 metals (Ag, Au, etc.) other than copper, Group 12 metals (Zn, etc.), Group 13 metals (Al, etc.) can be exemplified. The cocatalyst may contain one or more of these metal elements.

  The co-catalyst may be a simple metal or a metal compound, for example, an oxide, hydroxide, salt (inorganic acid salt such as sulfate, phosphate, nitrate, carbonate, etc .; organic acid such as carboxylate Salt, etc.). The cocatalyst may be composed of a kind of simple metal or metal compound, and may contain a plurality of these types of cocatalysts. Among these promoters, oxides such as alkali metal oxides such as sodium oxide, alkaline earth metal oxides such as calcium oxide and barium oxide are preferable. Such an alkali metal or alkaline earth metal oxide has an appropriate basicity, and even when a support having a high surface acidity or another promoter is used, the surface acidity of the solid catalyst. The (surface acid amount) can be adjusted to a specific range, which is advantageous for the reaction.

  In addition, the ratio (weight ratio) of copper (metal copper or a copper compound etc.) and a promoter is 0.1 / 100-300 / 100, for example, Preferably it is 1 / 100-150 / 100, More preferably, it is 5 / 100 to 80/100 (for example, 10/100 to 50/100).

  Copper and / or the above promoter may be supported on a support. Note that different types of compounds are usually used for the promoter and the carrier. Examples of such a carrier include activated carbon, zeolite, bentonite, silica (or silicon oxide), zirconia, titania, and oxides of metals other than copper. Examples of metal oxides include Group 4 metal oxides of the periodic table (titanium oxide, zirconium oxide, etc.), Group 5 metal oxides such as vanadium oxide, and Group 6 metal oxides such as chromium oxide, molybdenum oxide, and tungsten oxide. Examples include Group 7 metal oxides such as manganese oxide, Group 12 metal oxides such as zinc oxide, and Group 13 metal oxides such as aluminum oxide. These carriers can be used alone or in combination of two or more.

  Of the above carriers, silicon oxide, zirconium oxide, Group 6 metal oxide (such as chromium oxide), Group 13 metal oxide (such as aluminum oxide) and the like are preferable. In particular, a carrier having a relatively low surface acidity, such as silicon oxide or zirconium oxide, may be used as the carrier. Among them, it is preferable to use silicon oxide which has almost no surface acidity, can easily obtain a large surface area, is excellent in chemical stability and heat resistance, and has no toxicity.

  Further, a carrier having a low surface acidity (such as silicon oxide and / or zirconium oxide) and a carrier having a high surface acidity (such as a periodic table Group 6 metal oxide such as chromium oxide) may be combined. In addition, when a carrier having a low surface acidity such as silicon oxide or zirconium oxide and a carrier having a relatively high surface acidity such as chromium oxide are used in combination, the ratio of the carrier having a high surface acidity (such as chromium oxide) For example, 50 parts by weight or less, preferably 0.01 to 30 parts by weight, and more preferably about 0.1 to 15 parts by weight with respect to 100 parts by weight of a carrier having low surface acidity (silicon oxide, zirconium oxide, etc.). There may be.

  Of the solid catalysts, a catalyst in which copper and an alkali metal and / or alkaline earth metal promoter are supported on a carrier is preferable. The ratio of copper (or copper compound) is, for example, 0.1 to 300 parts by weight, preferably 1 to 200 parts by weight (for example, 2 to 150 parts by weight), more preferably 3 to 100 parts by weight of the carrier. It may be about 100 parts by weight (for example, 5 to 80 parts by weight). The ratio of the alkali metal and / or alkaline earth metal (or compound) is, for example, 0.1 to 80 parts by weight (for example, 0.1 to 50 parts by weight), preferably 100 parts by weight of the carrier, It may be about 1 to 50 parts by weight, more preferably about 2 to 30 parts by weight.

  The solid catalyst is the above-described copper compound, promoter (such as an alkali metal and / or alkaline earth metal compound), or a compound having these compounds supported on a carrier as it is as a catalyst, under a reducing atmosphere generated by the reaction. A method of using a copper compound as an active copper catalyst (such as metallic copper) may be used. If the activity is low or inactive as it is, activation treatment (reduction activation treatment, etc.) is appropriately performed by a conventional activation method. ) May be used.

  Supporting copper, a copper compound, a cocatalyst or the like on a carrier can be performed by a conventional method (coprecipitation method, impregnation method, etc.). For example, a mixture in which a copper compound is dissolved or dispersed in a solvent may be mixed (including kneading) with a cocatalyst and / or a carrier, and may be supported by removing the solvent as necessary. Alternatively, an active ingredient such as a copper compound may be immobilized on the carrier by oxidation treatment, reduction treatment, or the like. When copper oxide is supported on a carrier, for example, a solution in which a salt such as copper nitrate is dissolved in a solvent, and a carrier (silicon oxide, chromium oxide, aluminum oxide, etc., alkali metal such as magnesium oxide, barium oxide, or the like) It can be supported by converting a copper salt (such as copper nitrate) to copper oxide by oxidation treatment. In addition, a support (a combination of silicon oxide, silicon oxide, and other metal oxides (for example, oxides of Group 6 metal such as chromium oxide)), a copper compound (such as copper oxide), and a promoter At least copper (or a copper compound) is obtained by subjecting a precursor supporting an alkali metal and / or alkaline earth metal compound (such as an oxide such as sodium oxide, barium oxide, and calcium oxide) to reduction activation treatment. ) May be used as an activated solid catalyst. For example, a copper compound such as copper oxide may be converted to metallic copper by reduction activation treatment.

  The reduction activation can be performed by heating a solid catalyst or a precursor thereof (such as a low activity or inactive solid catalyst) in a reducing gas (such as a hydrogen-containing gas) atmosphere. A reducing gas such as a hydrogen-containing gas may be diluted with an inert gas (helium gas, nitrogen gas, argon gas, etc.) if necessary. The heating temperature can be appropriately selected depending on the kind of the solid catalyst or its precursor, and may be, for example, about 100 to 300 ° C, preferably 120 to 250 ° C, and more preferably about 150 to 220 ° C.

  The solid catalyst may be used after being formed into various shapes such as powders, granules and pellets depending on the reaction form such as fixed bed and fluidized bed used. Moreover, you may use a commercial item as a solid copper catalyst or its precursor.

  The solid catalyst may have a surface acid amount of 0 to 3 mmol / g, preferably about 0.0001 to 1 mmol / g, as measured by ammonia temperature programmed desorption (TPD). The solid catalyst has a surface acid amount by an ammonia TPD method of 0.10 mmol / g or less (for example, 0 to 0.10 mmol / g), preferably 0.0001 to 0.07 mmol / g, more preferably 0.001 to 0.001. It may be about 0.05 mmol / g, particularly about 0.05 to 0.04 mmol / g. The surface acid amount of the solid catalyst can be adjusted by combining a carrier, a cocatalyst, etc. based on the surface acid amount of these components, or adjusting the ratio thereof.

[Regeneration method of solid copper catalyst]
(Deactivation of solid copper catalyst)
The deactivated solid copper catalyst is obtained by reacting the solid copper catalyst with a reaction applied, for example, dehydrogenation or hydrogenation reaction (for example, production of a carbonyl compound (aldehyde, ketone, etc.) by dehydrogenation of an alcohol, carbonyl compound It means a catalyst which has been used for the production of alcohol by hydrogenation of the catalyst and has a lower activity than the catalyst activity obtained at the beginning of the reaction.

  In particular, in the present invention, a solid copper catalyst grows a crystal of catalytically active copper (metal copper, copper compound, etc.) by sintering due to the above reaction (especially, reaction at high temperature in a reduced state), etc. In the state where the surface area of the solid copper catalyst is reduced, or the sulfur-containing catalyst poison component contained in the reaction system or by-produced is adsorbed on the solid copper catalyst and combined with active copper, the copper catalyst is poisoned. It means the state.

The sulfur-containing catalyst poison component is not particularly limited as long as it is a component that poisons the copper catalyst. For example, hydrogen sulfide, sulfide (metal sulfide, etc.), mercaptan, etc., depending on the type of reaction and the type of raw material. (Alkyl mercaptans such as methyl mercaptan and ethyl mercaptan), sulfuric acid or esters thereof (such as alkyl sulfates such as methyl sulfate and ethyl sulfate), sulfonic acids or esters thereof (such as alkyl sulfonates such as methyl sulfonate and ethyl sulfonate) , Sulfoxides (alkyl sulfoxides such as dimethyl sulfoxide and diethyl sulfoxide), sulfides (alkyl sulfides such as dialkyl sulfides such as dimethyl sulfide and diethyl sulfide (di-C _1-4 alkyl sulfide etc.)), and the like. One or two or more of these sulfur-containing components may be contained in the reaction system. In particular, when an alcohol is used as a reaction raw material, a sulfide compound such as the sulfide may be contained. In particular, bioethanol inevitably contains alkyl sulfides (such as dimethyl sulfide). Therefore, even when such a sulfur-containing catalyst poison component is included in the reaction system and the copper catalyst is poisoned, the regeneration method of the present invention can efficiently activate and regenerate the copper catalyst. Can do.

  Sintering and adsorption of sulfur-containing poisoning components usually occur more severely under conditions. For example, metallic copper or a copper compound tends to crystallize due to a reaction at a high temperature, a reaction for a long time, a reaction under a reduction, or a combination of these conditions. For example, in the production of aldehydes by dehydrogenation of alcohol, the higher the reaction temperature, the more the equilibrium moves to the aldehyde side, so the reaction at high temperature is advantageous, but the sintering and the adsorption of poisoning components are likely to occur. .

  In the present invention, since the catalyst deactivated by sintering or adsorption of sulfur-containing poisoning components can be easily regenerated, the dehydrogenation reaction of alcohol can be performed at a high temperature, and the aldehyde can be produced efficiently. The reaction temperature may be, for example, about 150 to 400 ° C, preferably about 170 to 350 ° C, and more preferably about 200 to 300 ° C.

  In addition, the reaction may be performed under normal pressure or reduced pressure, but even if the reaction is performed under pressure, the catalyst can be efficiently regenerated after the reaction. The reaction time may be, for example, 30 minutes to 3000 hours, preferably 1 to 1500 hours, more preferably about 10 to 1000 hours. In particular, even a catalyst deactivated by sintering or adsorption of sulfur-containing poisoning components after a long reaction of about 300 to 2000 hours, preferably about 500 to 1000 hours, according to the regeneration method of the present invention, The catalyst can be activated effectively.

  Although the degree of deactivation of the solid copper catalyst is not particularly limited, it is 0 to 90, preferably 1 to 85, more preferably 5 to 80 (particularly 10 ˜75).

  The regeneration method of the present invention can be advantageously applied particularly to a solid copper catalyst deactivated in the production of an aldehyde by dehydrogenation of alcohol.

  In the production of aldehyde, the deactivated solid copper catalyst can be obtained in the process of deactivating alcohol by bringing active solid copper catalyst into contact with alcohol and synthesizing the corresponding aldehyde.

Substrate alcohol, which is a raw material for producing aldehydes, includes primary alcohols such as aliphatic primary alcohols such as methanol, ethanol, 1-propanol and 1-butanol (such as 1-C _1-6 alkanol), and 2-cyclohexylmethanol. Examples include alicyclic primary alcohols (C _5-8 cycloalkyl-C _1-6 alkanols, etc.), aromatic primary alcohols such as benzyl alcohol, phenethyl alcohol (C _6-10 aryl-C _1-6 alkanols, etc.) and the like. . These alcohols have substituents such as halogen atoms such as fluorine, chlorine, bromine and iodine atoms; alkyl groups such as methyl and ethyl groups (such as C _1-4 alkyl groups); and C _5-8 cyclo such as cyclohexyl groups. An alkyl group; a C _6-10 aryl group such as a phenyl group; a nitro group; an amino group or an N-substituted amino group; In addition, these substituents may be substituted on an aliphatic portion (alkyl group portion), a cycloalkane ring and / or an arene ring of alcohol. Preferred alcohols are 1-C _1-4 alkanols such as methanol, ethanol, especially ethanol.

  The alcohol used for the reaction may be a hydrous alcohol. The amount of water in the alcohol may be, for example, about 0.01 to 30% by weight, preferably about 0.1 to 15% by weight, and more preferably about 0.5 to 10% by weight.

  By dehydrogenation of the alcohol, an aldehyde in which the hydroxyl group portion of the alcohol is converted to an oxo group is generated. For example, acetaldehyde can be obtained by dehydrogenation of ethanol.

  The reaction may be a liquid phase reaction as long as the alcohol can be brought into contact with the solid catalyst, but is usually a gas phase reaction in which the gaseous alcohol and the solid catalyst are contacted in the gas phase.

  When the reaction is performed in a batch reaction mode in the liquid phase, the ratio of the solid catalyst to the substrate alcohol is, for example, 0.1 to 30 parts by weight, preferably 1 to 20 parts by weight, more preferably 100 parts by weight of the alcohol. May be about 2 to 10 parts by weight.

The reaction may be carried out batchwise but is preferably carried out continuously. In the case of continuous reaction, the liquid space velocity (LHSV) of the alcohol may be, for example, about 0.5 to 20 h ⁻¹ , preferably ¹ to 10 h ⁻¹ , more preferably about 2 to 7 h ⁻¹ .

  In addition, the usage form of the solid catalyst can be appropriately selected from conventional forms in consideration of the physical properties and productivity of the substrate. For example, the gas phase fixed bed, the gas phase fluidized bed, the liquid phase fixed bed, or the liquid phase fluidized bed It may be.

(Catalyst regeneration)
In the regeneration method of the present invention, as described above, the solid copper catalyst deactivated by sintering or adsorption of the sulfur-containing catalyst poison component is regenerated by oxidizing with an oxygen-containing gas and further reducing with a hydrogen-containing gas.

  In the oxidation step, the oxygen-containing gas to be used may contain molecular oxygen, pure oxygen gas (molecular oxygen) may be used, and molecular oxygen is used as an inert gas (helium, nitrogen, argon gas, etc.). ), Diluted with air, carbon dioxide or the like. Air may be used as the oxygen-containing gas. If pure oxygen-containing gas is used, the temperature of the solid copper catalyst is likely to rise more than necessary, so that it is usually often diluted with an inert gas or air.

  The oxidation step can be performed by bringing an oxygen-containing gas into contact with the deactivated solid copper catalyst. When a catalyst is subsequently regenerated after a reaction using a catalyst (for example, aldehyde production using alcohol as a raw material), an oxygen-containing gas is added to the reactor while the deactivated catalyst is accommodated in the reactor. Thus, the deactivated catalyst can be easily oxidized.

  The oxidation temperature (the temperature of the solid copper catalyst) may be 150 to 500 ° C. (for example, 200 to 500 ° C.), preferably 170 to 450 ° C., more preferably about 180 to 400 ° C. The oxidation reaction proceeds more rapidly as the temperature increases, but if the catalyst becomes too high, sintering of the support other than copper and the promoter component may proceed irreversibly. Further, when the oxidation treatment is performed in the reactor, there is a possibility that an abnormal temperature rise of the catalyst may occur due to oxidation heat. Therefore, it is preferable to dilute molecular oxygen with an inert gas such as nitrogen gas as necessary.

  The oxidation treatment may be performed under normal pressure or under pressure. The treatment time of the oxidation treatment can be appropriately selected from the range of, for example, about 1 to 100 hours, preferably 1.5 to 50 hours, more preferably about 2 to 24 hours (for example, 3 to 12 hours). Good.

  By such an oxidation treatment, the copper catalyst is oxidized and a sulfur-containing catalyst poison component such as dimethyl sulfide is oxidized. For example, when the copper catalyst is metallic copper, it is changed to copper oxide by oxidation of metallic copper, and sulfides such as dimethyl sulfide are changed to sulfur-containing oxide by oxidation.

  In the present invention, in particular, a deactivated copper catalyst (such as a copper catalyst deactivated in the aldehyde production process by dehydrogenation of alcohol) is used as a solvent (hydrocarbon, halogen-based solvent, alcohol, ketone, ether, amide, etc.). It is subjected to oxidation with an oxygen-containing gas without any oil removal treatment with an organic solvent or the like or pretreatment with a hydrogen-containing gas. Therefore, even a copper catalyst deactivated by sintering or adsorption of a sulfur-containing catalyst poison component can be effectively oxidized, and a sulfur-containing catalyst poison component can also be oxidized.

  The solid copper catalyst after the oxidation treatment is further subjected to a reduction process using a hydrogen-containing gas. The hydrogen-containing gas used in the reduction process may be pure hydrogen gas (molecular hydrogen), or the hydrogen gas may be diluted with an inert gas (helium, nitrogen, argon, etc.) or air. Good. The reduction reaction of the oxidized copper catalyst (such as copper oxide) is an exothermic reaction, and it is preferable to appropriately dilute the hydrogen gas with an inert gas such as nitrogen gas in order to prevent the temperature of the catalyst from rising more than necessary. .

  The temperature of the reduction step is, for example, room temperature (about 20 to 30 ° C.) to 300 ° C., preferably 50 to 250 ° C., more preferably about 100 to 200 ° C. In addition, when temperature is too high, the sintering which the reduced copper catalyst crystallizes may become easy to advance.

  The reduction reaction may be liquid-phase reduced in an inert solvent (hydrocarbon, ester, alcohol, fats and oils (higher fatty acid, ester or amide thereof, etc.)), but is usually performed in the gas phase. Further, the reduction treatment may be performed under normal pressure or under pressure.

  The reduction time may be, for example, about 1 to 50 hours, preferably 1.5 to 24 hours, more preferably 2 to 12 hours (particularly 3 to 10 hours).

  By such a reduction process, the copper catalyst (such as copper oxide) oxidized in the oxidation process can be converted into an active copper catalyst (such as metallic copper). The obtained active copper catalyst can be used for various reactions (for example, aldehyde production, alcohol production, etc.).

  In the present invention, the deactivated solid copper catalyst is oxidized with an oxygen-containing gas and reduced with a hydrogen-containing gas, so even a solid copper catalyst deactivated by sintering or adsorption of a sulfur-containing catalyst poison component is effective. Can be played. Therefore, the regeneration method of the present invention is useful for regeneration treatment of a deactivated catalyst obtained by various production methods using a solid copper catalyst (particularly, an industrial production method such as an aldehyde production method using alcohol as a raw material). It is. Moreover, since it can apply also to the process of the deactivation catalyst obtained by aldehyde manufacture using the alcohol etc. which are obtained by biomass fermentation methods, such as bioethanol, it is useful also from the point of a depetroleum raw material.

  Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.

Example 1
(1) Reduction activation step 6 ml of a solid catalyst whose composition is CuO: Cr ₂ O ₃ : BaO: SiO ₂ (weight ratio = 40: 38: 12: 10) is filled in a stainless steel reaction tube, The air was replaced with nitrogen gas, and then hydrogen gas and nitrogen gas were allowed to flow through the reaction tube at a flow rate of 3 L / hr, respectively. When the heat generation was almost subsided, the hydrogen gas flow rate was 6 L / hr, the nitrogen gas was 0 L / hr, and the catalyst layer was held at a temperature of 170 ° C. for 6 hours to carry out reduction activation treatment. By the reduction activation treatment, the copper oxide in the catalyst layer was converted to metallic copper which is a catalytically active species.

(2) Dehydrogenation reaction step Next, water-containing ethanol (water content: 6% by weight) is charged into the reaction tube at a supply rate of LHSV = 4.0 h ⁻¹ , and the dehydrogenation reaction is performed at a catalyst layer temperature of 260 ° C. and normal pressure. Went. As a result of analyzing the obtained reaction crude liquid with a gas chromatograph, from the analysis of the reaction crude liquid obtained in the initial stage of the reaction (from the start of raw material charging to 16 hours after the charging), the conversion rate of raw ethanol at the initial stage of reaction is The acetaldehyde selectivity based on the consumption ethanol was 42.6% and 86.0%. Moreover, when the reaction crude liquid was analyzed after continuing reaction for 700 hours on the same conditions, the ethanol conversion rate fell to 31.5%.

(3) Catalyst regeneration step After 700 hours of reaction, with the catalyst in the reaction tube, air 3.0 L / hr (STP conversion value, the same applies hereinafter) and nitrogen gas 3.0 L / hr were passed through the reaction tube. The catalyst layer was heated to a temperature of 300 ° C. When the heat generation was almost subsided, the supply of nitrogen gas was stopped, the flow rate of air was 6.0 L / hr, the flow rate of nitrogen gas was 0 L / hr, and the catalyst layer was heated to 400 ° C. and held for 12 hours. . Next, the temperature of the catalyst layer was lowered to 160 ° C., the air in the reaction tube was replaced with nitrogen gas, and hydrogen gas and nitrogen gas were flowed at a flow rate of 3 L / hr, respectively. When the heat generation was almost subsided, the flow rate of hydrogen gas was 6 L / hr, the flow rate of nitrogen gas was 0 L / hr, and the catalyst layer was held at a temperature of 170 ° C. for 6 hours.

(4) Dehydrogenation reaction step using regenerated catalyst Using the catalyst regenerated in step (3) above, ethanol dehydrogenation reaction was performed under the same conditions as in step (2) above. From the analysis of the reaction crude liquid obtained at the initial stage (between 12 hours and 16 hours after the raw material was charged), the raw material ethanol conversion was 46.0% and the acetaldehyde selectivity was 82.7%.

Example 2
(1) Reduction activation step The catalyst activation is performed in the same manner as in the reduction activation step of Example 1 except that a solid catalyst having a composition of Cu0: SiO ₂ : Na ₂ O (weight ratio = 68: 30: 2) is used. Made.

(2) Dehydrogenation reaction step Ethanol dehydrogenation reaction was performed in the same manner as in step (2) of Example 1 except that the catalyst layer temperature was 270 ° C. From the analysis of the reaction crude liquid at the initial stage of the reaction (between 12 and 16 hours after the raw material was charged), the conversion rate of the raw material ethanol at the initial stage of the reaction was 46.7%, and the acetaldehyde selectivity based on the consumed ethanol was 88.6%. It was. Moreover, when the reaction crude liquid was analyzed after continuing reaction on the same conditions for 700 hours, the ethanol conversion rate fell to 37.6%.

(3) Catalyst regeneration step After 700 hours of reaction, the catalyst was regenerated in the same manner as in step (3) of Example 1 with the catalyst in the reaction tube.

(4) Dehydrogenation reaction step using regenerated catalyst Using the catalyst regenerated in step (3) above, ethanol dehydrogenation reaction was performed under the same conditions as in step (2) above. From the analysis of the reaction crude liquid at the initial stage (between 12 hours and 16 hours after the raw material was charged), the raw material ethanol conversion was 45.6% and the acetaldehyde selectivity was 89.3%.

Example 3
In the same manner as in Example 1, the solid catalyst was reduced and activated to perform a dehydrogenation reaction. From the analysis of the reaction crude liquid at the initial stage of the reaction (between 12 and 16 hours after the raw material was charged), the conversion ratio of the raw material ethanol at the initial stage of the reaction was 43.2%, and the acetaldehyde selectivity based on the consumed ethanol was 89.0%. It was.

  930 ppm equivalent of dimethyl sulfide was added to the raw material ethanol, and the dehydrogenation reaction was continued. After the addition of dimethyl sulfide, the ethanol conversion after 70 hours was 4.7%, and the acetaldehyde selectivity was 83.3%. 70 hours after the addition of dimethyl sulfide, the catalyst was regenerated in the same manner as in step (3) of Example 1 with the catalyst in the reaction tube.

  When ethanol was dehydrogenated using the regenerated solid catalyst under the same conditions as in Step (2) of Example 1, the reaction crude in the initial stage of the reaction (between 12 hours and 16 hours after the raw material was charged). From the analysis of the liquid, the raw material ethanol conversion was 44.6%, and the acetaldehyde selectivity was 84.7%.

Claims (6)

The deactivated solid copper catalyst was deactivated by sintering by use under high temperature and reducing atmosphere, or by adsorption of sulfide compound as sulfur-containing catalyst poison component, oxidized with oxygen-containing gas and further reduced with hydrogen-containing gas A method for regenerating a copper catalyst,
The deactivated solid copper catalyst is a copper catalyst obtained by dehydrogenating ethanol in the presence of a solid copper catalyst, and the solid copper catalyst used for the dehydrogenation is a carrier composed of silicon oxide. In addition, a catalyst obtained by reducing and activating a precursor on which a copper compound capable of generating metallic copper by reduction and an alkali metal and / or alkaline earth metal promoter is supported,
The copper catalyst deactivated in the aldehyde production process by ethanol dehydrogenation can be oxidized with an oxygen-containing gas at a temperature of 200 to 500 ° C. without removing the oil with a solvent or pretreating with a hydrogen-containing gas. And a reduction method in which the gas is further reduced in a gas phase with a hydrogen-containing gas at a temperature of 100 to 200 ° C.   The method according to claim 1, wherein the ethanol is hydrous ethanol and the aldehyde is acetaldehyde. The method according to claim 1 or 2, wherein the oxidation temperature is 200 to 400 ° C. The process according to any one of claims 1 to 3, wherein the sulfur-containing catalyst poison component is a _diC1-4 alkyl sulfide.   A method for producing an aldehyde by dehydrogenating ethanol in the presence of the solid copper catalyst regenerated by the method according to claim 1.   6. A process according to claim 5, wherein the aldehyde is acetaldehyde.