JP2009029729A - METHOD FOR PRODUCING alpha,beta-UNSATURATED CARBOXYLIC ACID - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the productivity of the objective α,β-unsaturated carboxylic acid, in the production of α,β-unsaturated carboxylic acid by the liquid-phase oxidization of an alcohol, an olefin or an α,β-unsaturated aldehyde with molecular oxygen. <P>SOLUTION: The method for producing an α,β-unsaturated carboxylic acid comprises the liquid-phase oxidization of an alcohol, an olefin or an α,β-unsaturated aldehyde with molecular oxygen in the presence of a catalyst containing palladium and tellurium and in the presence of a molybdenum compound in the reaction system. The molybdenum compound can be made to be present in the liquid-phase oxidization reaction system by (A) a method to support the molybdenum compound on the catalyst; (B) a method to use a supported catalyst and support the molybdenum compound on the carrier in the catalyst; (C) a method to dissolve and/or disperse the molybdenum compound in the reaction liquid to perform the liquid-phase oxidization; etc. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a process for producing an α, β-unsaturated carboxylic acid by liquid phase oxidation of an alcohol, olefin or α, β-unsaturated aldehyde with molecular oxygen in the presence of a catalyst containing palladium and tellurium.

  As a method for producing α, β-unsaturated carboxylic acid by liquid phase oxidation of olefin with molecular oxygen, palladium metal or an intermetallic compound of palladium metal and other metals (lead, bismuth, thallium, mercury, etc.) A method using a palladium catalyst composed of a low-order oxidation state compound is known (Patent Document 1). The method described in Patent Document 1 oxidizes an olefin in the presence of an aqueous solution of at least one molybdenum compound selected from the group consisting of molybdenum oxide, heteropolymolybdic acid and heteropolymolybdate and the palladium catalyst. It is characterized by.

In addition, as a method for producing an α, β-unsaturated carboxylic acid by liquid phase oxidation of olefin with molecular oxygen, palladium containing 0.001 to 0.40 mol of tellurium metal with respect to 1.0 mol of palladium metal A method using a catalyst is known (Patent Document 2).
JP 56-59722 A International Publication No. 2005/118134 Pamphlet

  However, in the method described in Patent Document 1 or 2, the productivity of the target product α, β-unsaturated carboxylic acid is not yet sufficient, and further improvement in productivity has been desired. Moreover, it is preferable to have the same performance in the production of α, β-unsaturated carboxylic acid by liquid phase oxidation of alcohol or α, β-unsaturated aldehyde.

  Therefore, the present invention provides an α, β-unsaturated product which is the target product in the production of α, β-unsaturated carboxylic acid by liquid phase oxidation of alcohol, olefin or α, β-unsaturated aldehyde with molecular oxygen. It aims at improving productivity of saturated carboxylic acid.

  The present invention is a process for producing an α, β-unsaturated carboxylic acid by liquid phase oxidation of an alcohol, olefin or α, β-unsaturated aldehyde with molecular oxygen in the presence of a catalyst containing palladium and tellurium. And a process for producing an α, β-unsaturated carboxylic acid, wherein a molybdenum compound is present in the reaction system.

  According to the present invention, when α, β-unsaturated carboxylic acid is produced by liquid phase oxidation of alcohol, olefin or α, β-unsaturated aldehyde with molecular oxygen, the target product α, β-unsaturated is produced. The productivity of saturated carboxylic acid can be increased.

  In the present invention, a catalyst containing palladium and tellurium is used to produce an α, β-unsaturated carboxylic acid by liquid phase oxidation of alcohol, olefin or α, β-unsaturated aldehyde with molecular oxygen, and A molybdenum compound is present in the reaction system. The presence of a molybdenum compound in a reaction system in which liquid phase oxidation is carried out using a catalyst containing both palladium and tellurium greatly enhances the productivity of the target product α, β-unsaturated carboxylic acid. Can do.

  As the molybdenum compound to be present in the reaction system for performing liquid phase oxidation, molybdenum oxide such as molybdenum dioxide and molybdenum trioxide; heteropolymolybdic acid such as phosphomolybdic acid and silicomolybdic acid; and salts of the heteropolymolybdic acid are used. be able to. Examples of the salt of heteropolymolybdic acid include alkali metal salts such as Li salt, Na salt and K salt, and alkaline earth metal salts such as Ca salt, Sr salt and Ba salt. A molybdenum compound may be used alone or in combination of two or more.

  The molybdenum compound is (A) a method of supporting a molybdenum compound on a catalyst; (B) a method of using a supported catalyst and supporting a molybdenum compound on a support in the catalyst; (C) a reaction solution for performing liquid phase oxidation. The molybdenum compound can be present in the reaction system in which liquid phase oxidation is performed by a method of dissolving and / or dispersing the molybdenum compound therein.

  The chemical state of palladium in the catalyst may be a metallic state or an oxidized state, but it is preferable that the palladium is in a metallic state because it exhibits high catalytic activity. The chemical state of tellurium in the catalyst may be a metallic state or an oxidized state, but tellurium is preferably in a metallic state because it changes the electronic state of palladium more. Moreover, since palladium and tellurium are adjacent to each other, the percentage of palladium in which the electronic state is greatly changed is increased. Therefore, tellurium is preferably alloyed with palladium or formed an intermetallic compound.

  The molar ratio of tellurium to palladium (Te / Pd) needs to exceed 0, but is preferably 0.001 to 0.40, more preferably 0.002 to 0.30, and 0.003 to 0.00. 25 is more preferable. By using a catalyst containing palladium and tellurium at such a molar ratio, the selectivity and productivity of the α, β-unsaturated carboxylic acid can be further increased. Te / Pd can be adjusted by the blending ratio of the palladium and tellurium raw materials used in the production of the catalyst.

Te / Pd can be calculated from the mass and atomic weight of palladium and tellurium in the catalyst. The masses of palladium and tellurium in the catalyst can be measured by sequentially performing the following steps.
-Preparation of treatment solution A: 0.2 g of catalyst and predetermined amounts of concentrated nitric acid, concentrated sulfuric acid, and hydrogen peroxide solution are placed in a Teflon (registered trademark) decomposition tube and dissolved in a microwave heat decomposition apparatus. The sample is filtered, and the filtrate and washing water are combined, and the volume is made up in a volumetric flask to obtain the treatment solution A.
-Preparation of B treatment liquid: The filter paper which collected the insoluble part in the preparation of A treatment liquid is transferred to a platinum crucible, heated and incinerated, and then added with lithium metaborate and melted with a gas burner. After cooling, add hydrochloric acid and a small amount of water in a crucible and dissolve, then add up to a volumetric flask to make the B treatment solution.
Quantitative determination of palladium and tellurium in the catalyst: The masses of palladium and tellurium contained in the obtained A treatment liquid and B treatment liquid were each quantified with an ICP emission spectrometer, and the total values of palladium and tellurium in the catalyst were respectively determined. Mass.

  The catalyst may contain other metal elements. Examples of other metal elements include noble metal elements such as platinum, rhodium, ruthenium, iridium, gold, silver and osmium; and base metal elements such as bismuth, antimony, thallium, lead and mercury. Two or more kinds of other metal elements contained in the catalyst may be used. From the viewpoint of expressing high catalytic activity, the total amount of palladium and tellurium among the metal elements contained in the catalyst is preferably 25% by mass or more, more preferably 50% by mass or more, and 80% by mass or more. More preferably.

  The catalyst may be an unsupported type, but is preferably a supported type in which palladium and tellurium are supported on a carrier. As the carrier, activated carbon, carbon black, silica, alumina, magnesia, calcia, titania, zirconia and the like can be used. Among these, activated carbon, silica, alumina, titania and zirconia are preferable. One type of carrier may be used, or two or more types may be used in combination. When using 2 or more types of support | carriers together, the mixture which mixed silica and an alumina can also be used, for example, and complex oxides, such as a silica-alumina, can also be used.

Since the specific surface area of the preferred carrier varies depending on the kind of the carrier, it cannot be generally stated. For example, the specific surface area of the activated carbon support is preferably ^{100~5000m 2 / g, 300~4000m 2 /} g is more preferable. The specific surface area of the silica support is preferably 10~2000m ² / g, more preferably 50~1500m ² / g, more preferably 100~1000m ² / g. The smaller the specific surface area of the support is, the more the components with useful components (palladium and tellurium) supported on the surface can be produced. The larger the range, the more the components with useful components supported. . The specific surface area of the carrier can be measured by a nitrogen gas adsorption method.

  The pore volume of the carrier is preferably from 0.1 to 2.0 cc / g, more preferably from 0.2 to 1.5 cc / g.

  The supported rate of palladium in the supported catalyst is preferably 1% by mass to 40% by mass, more preferably 2% by mass to 30% by mass, and even more preferably 4% by mass to 20% by mass with respect to the mass of the carrier before being supported. .

  The mass of the carrier used can be measured by an appropriate method depending on the type of the carrier. For example, in the case of a silica support, the catalyst is placed in a platinum crucible, melted by adding sodium carbonate, and distilled water is added to form a homogeneous solution. By quantifying Si atoms in the sample solution with ICP, the mass of silicon element is obtained. And the mass of the silica support can be calculated. In the case of a titania carrier or zirconia carrier, the catalyst is placed in a Teflon (registered trademark) decomposition tube, concentrated sulfuric acid and hydrofluoric acid are added, dissolved in a microwave thermal decomposition apparatus, distilled water is added as a uniform solution, and the sample solution is obtained by ICP By quantifying the Ti atom or Zr atom in the medium, the mass of the titanium element or zirconia element can be obtained, and the mass of the titania carrier or zirconia carrier can be calculated.

  When the molybdenum compound is present in the reaction system in which liquid phase oxidation is performed by the method (A) or (B) described above, the content of the molybdenum compound in the catalyst is 1 with respect to 100 parts by mass of palladium in the catalyst. -5000 mass parts is preferable, 5-1000 mass parts is more preferable, and 10-500 mass parts is further more preferable.

  The above catalyst can be manufactured using the raw material which supplies palladium and tellurium. When the catalyst contains another metal element, a raw material for supplying the metal element may be used in combination. As a raw material, a single metal of each element, an alloy of two or more of these, or a compound containing each element can be used. Such raw materials are appropriately selected, and the amount of the raw materials used is appropriately adjusted so that a catalyst having a target composition can be obtained.

  As the raw material of palladium, palladium metal, palladium salt, palladium oxide and the like can be used. Of these, palladium salts are preferred. Examples of the palladium salt include palladium chloride, palladium acetate, palladium nitrate, palladium sulfate, tetraammine palladium chloride, bis (acetylacetonato) palladium and the like. Among these, palladium chloride, palladium acetate, palladium nitrate, and tetraammine palladium chloride are preferable, and palladium nitrate is more preferable. The palladium raw material may be used alone or in combination of two or more.

  As a raw material of tellurium, tellurium metal, tellurium salt, telluric acid and its salt, telluric acid and its salt, tellurium oxide and the like can be used. Of these, telluric acid and its salt, telluric acid and its salt, and tellurium oxide are preferred. Examples of tellurium salts include hydrogen telluride, tellurium tetrachloride, tellurium dichloride, tellurium hexafluoride, tellurium tetraiodide, tellurium tetrabromide, tellurium dibromide and the like. Examples of tellurate include sodium tellurate and potassium tellurate. Examples of tellurite include sodium tellurite and potassium tellurite. One type of tellurium raw material may be used, or two or more types may be used in combination.

  As a method for producing the catalyst, a method having a step of reducing a compound containing palladium element in an oxidized state with a reducing agent and a step of mixing a compound containing tellurium element in an oxidized state is preferable. Furthermore, you may have the process of reduce | restoring the tellurium element of an oxidation state with a reducing agent. Moreover, the tellurium element can be reduced simultaneously with the reduction of the palladium element by mixing the compound containing the tellurium element before reducing the palladium element. When the reduction of palladium element and the reduction of tellurium are performed in separate steps, the reduction of palladium element may be performed first, or the reduction of tellurium element may be performed first. The conditions in these reduction steps can be set independently.

  As the reducing agent, one having at least the ability to reduce palladium element in an oxidized state can be used. Examples of reducing agents include hydrazine, formaldehyde, sodium borohydride, hydrogen, formic acid, formic acid salt, ethylene, propylene, 1-butene, 2-butene, isobutylene, 1,3-butadiene, 1-heptene, 2- Examples include heptene, 1-hexene, 2-hexene, cyclohexene, allyl alcohol, methallyl alcohol, acrolein, and methacrolein. One reducing agent may be used, or two or more reducing agents may be used in combination.

  The reduction with the reducing agent may be performed in the gas phase, but is preferably performed in the liquid phase. As a reducing agent when performing reduction in the gas phase, hydrogen is preferable. As a reducing agent when performing reduction in the liquid phase, hydrazine, formaldehyde, formic acid, and a salt of formic acid are preferable.

  However, it is preferable that the reducing agent does not contain sulfur. Here, the reducing agent not containing sulfur means that no sulfur element is contained in the structure of the reducing agent, that is, it is not a sulfur-containing compound, and is a reduction in which sulfur or a sulfur compound is contained as a small amount of impurities. The agent is not included. Since reduction with a reducing agent is preferably performed at a relatively low temperature, when a reducing agent that is a sulfur-containing compound is used, sulfur is strongly adsorbed on a carrier, palladium, tellurium, etc., and the activity of the resulting catalyst may be reduced. .

  The solvent used for the reduction in the liquid phase is preferably water. However, depending on the solubility of the raw material and the reducing agent and the dispersibility of the carrier when producing a supported catalyst, ethanol, 1-propanol, 2 Alcohols such as propanol, n-butanol and t-butanol; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone; organic acids such as acetic acid, n-valeric acid and isovaleric acid; heptane, hexane, cyclohexane and the like Organic solvents such as hydrocarbons can be used. 1 type may be used for an organic solvent and it may use 2 or more types together. A mixed solvent of an organic solvent and water can also be used.

  When the reducing agent is a gas, it is preferably carried out in a pressure device such as an autoclave that increases the solubility of the reducing agent in the solution. At that time, the inside of the pressurizer is pressurized with a reducing agent. The pressure is preferably 0.1 to 1.0 MPa (gauge pressure; hereinafter, pressure is expressed as gauge pressure).

  When the reducing agent is a liquid, the reduction can be performed by adding the reducing agent to the solution. The amount of the reducing agent used is preferably 1 to 100 moles per mole of the palladium element in the oxidized state.

  The reduction temperature is preferably -5 to 150 ° C, more preferably 15 to 80 ° C. The reduction time is preferably 0.1 to 4 hours, more preferably 0.25 to 3 hours, and further preferably 0.5 to 2 hours.

  When the molybdenum compound is present in the reaction system in which liquid phase oxidation is performed by the method (A) described above, a step of mixing the molybdenum compound may be performed when the catalyst is manufactured. By doing so, the molybdenum compound is supported on the catalyst. Since it is not necessary to reduce the molybdenum compound, the molybdenum compound can be mixed after the above reduction step. However, a molybdenum compound may be mixed before performing the above reduction step.

  When producing a supported catalyst, the raw material may be supported on a carrier. Examples of methods for supporting the raw material on the carrier include precipitation methods, ion exchange methods, impregnation methods, and deposition methods. When manufacturing by the impregnation method, the palladium raw material and the tellurium raw material may be impregnated and supported at the same time, or after impregnating and supporting one of the raw materials, the remaining raw materials may be impregnated and supported. The amount of the carrier used is appropriately adjusted so that a catalyst having a desired loading rate can be obtained.

  However, when an activated carbon-supported catalyst is produced, when a solution containing palladium raw material and tellurium raw material is contacted with a support (activated carbon), palladium element and tellurium element are formed by reaction with active groups present on the outer surface of the support. In some cases, the catalyst is reduced and deposited, and becomes a catalyst in which palladium metal and tellurium metal are unevenly distributed on the outer surface of the support. Accordingly, it is preferable that an appropriate amount of an oxidizing agent such as hydrogen peroxide, nitric acid, hypochlorous acid, or the like is present in the solution containing the palladium raw material and the tellurium raw material before the reduction with the reducing agent. Even in the case of other carriers, the palladium element and the tellurium element may be reduced depending on the production conditions. Similarly, the reduction can be prevented by the presence of an appropriate amount of an oxidizing agent.

  When the molybdenum compound is present in the reaction system in which liquid phase oxidation is performed by the method (B) described above, a step of supporting the molybdenum compound on the support in advance may be performed. For example, the molybdenum compound can be supported on the carrier by a method in which the carrier and the molybdenum compound are dissolved and / or dispersed in a solvent and then the solvent is removed. The solvent is preferably a solvent having a pH of 9 or less from the viewpoint of suppressing dissolution of the carrier in the solvent. The molybdenum compound may be dispersed in a solvent, or all or a part thereof may be dissolved in the solvent. The solvent can be removed by filtration, evaporation, dry-up, centrifugation, or the like. In addition, after removing the solvent, drying and / or firing may be performed as necessary. Drying can be performed by, for example, a general box-type dryer. Firing can be performed, for example, using a muffle furnace at a temperature not lower than the drying temperature and not higher than 800 ° C. with little structural change of the carrier. The firing time is preferably 0.5 to 24 hours.

  After the palladium raw material and the tellurium raw material are supported on the carrier, heat treatment may be performed before the reduction, so that palladium oxide and tellurium oxide are supported on the carrier. The heat treatment temperature is preferably from the decomposition temperature of the raw material used to 800 ° C, more preferably from 200 to 700 ° C. The heat treatment time is preferably 0.5 to 24 hours, more preferably 1 to 12 hours. The heat treatment may be performed in air or in an inert gas such as nitrogen.

  The produced catalyst is preferably washed with water, a solvent or the like. By washing with water, a solvent or the like, impurities derived from raw materials such as chloride, acetate radical, nitrate radical and sulfate radical are removed. Since some impurities may inhibit the liquid phase oxidation reaction, it is preferable to perform a method capable of sufficiently removing impurities and the number of times of washing. The washed catalyst may be recovered by filtration or centrifugation and used for the reaction as it is.

  Further, the recovered catalyst may be dried. For example, the catalyst can be dried in air or in an inert gas using a dryer. The dried catalyst can be activated prior to use for liquid phase oxidation if desired. For example, a method of heat-treating the catalyst in a reducing atmosphere in a hydrogen stream can be mentioned. According to this method, the oxide film on the palladium surface and impurities that could not be removed by washing can be removed.

  The physical properties of the produced catalyst can be confirmed by BET surface area measurement, XRD measurement, CO pulse adsorption method, TEM measurement, XPS measurement and the like.

  Next, a method for producing an α, β-unsaturated carboxylic acid by liquid phase oxidation of alcohol, olefin or α, β-unsaturated aldehyde with molecular oxygen will be described.

  As the raw material alcohol, 2-propanol, t-butyl alcohol, 2-butanol and the like can be used. Of these, 2-propanol and t-butyl alcohol are preferable. The raw material alcohol may contain a small amount of water, saturated hydrocarbons and / or lower saturated aldehydes as impurities. When alcohol is used as a raw material, it goes through a dehydration reaction, so that the α, β-unsaturated carboxylic acid produced is an α, β-unsaturated carboxylic acid having the same carbon skeleton as the olefin produced by the dehydration reaction. It is an acid. For example, when 2-propanol is used as the raw material, propylene is produced by a dehydration reaction, so that an α, β-unsaturated carboxylic acid having the same skeleton as propylene is produced. When the raw material is t-butyl alcohol, isobutylene is generated by a dehydration reaction, and thus an α, β-unsaturated carboxylic acid having the same skeleton as isobutylene is obtained.

  Propylene, isobutylene, 2-butene and the like can be used as the raw material olefin. Of these, propylene and isobutylene are preferable. The raw material olefin may contain a small amount of saturated hydrocarbon and / or lower saturated aldehyde as impurities. The α, β-unsaturated carboxylic acid produced is an α, β-unsaturated carboxylic acid having the same carbon skeleton as the olefin. For example, acrylic acid is produced when the raw material is propylene, and methacrylic acid is produced when the raw material is isobutylene.

  As the raw material α, β-unsaturated aldehyde, acrolein, methacrolein, crotonaldehyde (β-methylacrolein), cinnamaldehyde (β-phenylacrolein) and the like can be used. Of these, acrolein and methacrolein are preferable. The raw α, β-unsaturated aldehyde may contain a small amount of saturated hydrocarbon and / or lower saturated aldehyde as impurities. The α, β-unsaturated carboxylic acid produced is an α, β-unsaturated carboxylic acid in which the aldehyde group of the α, β-unsaturated aldehyde is changed to a carboxyl group. For example, acrylic acid is produced when the raw material is acrolein, and methacrylic acid is produced when the raw material is methacrolein.

  One kind of alcohol, olefin and α, β-unsaturated aldehyde as raw materials for the liquid phase oxidation reaction may be used, or two or more kinds may be used in combination.

  The liquid phase oxidation reaction may be performed in either a continuous type or a batch type, but in view of productivity, the continuous type is preferred industrially.

  As the source of molecular oxygen used in the liquid phase oxidation reaction, air is economical and preferable, but pure oxygen or a mixed gas of pure oxygen and air can also be used. These gases, nitrogen, carbon dioxide, water vapor, etc. A mixed gas diluted with can also be used. The gas serving as the source of molecular oxygen is preferably supplied in a pressurized state into a reaction vessel such as an autoclave.

  As a solvent used for the liquid phase oxidation reaction, t-butanol, cyclohexanol, acetone, methyl ethyl ketone, methyl isobutyl ketone, acetic acid, propionic acid, n-butyric acid, iso-butyric acid, n-valeric acid, iso-valeric acid, ethyl acetate An organic solvent such as methyl propionate can be used. Among these, t-butanol, methyl isobutyl ketone, acetic acid, propionic acid, n-butyric acid, iso-butyric acid, n-valeric acid, and iso-valeric acid are preferable. 1 type may be used for an organic solvent and it may use 2 or more types together. In order to produce the α, β-unsaturated carboxylic acid with higher selectivity, it is preferable to use a mixed solvent of an organic solvent and water. The content of water in the mixed solvent is preferably 2 to 70% by mass, and more preferably 5 to 50% by mass. The mixed solvent is preferably in a uniform state, but may be in a non-uniform state. When alcohol is used as a raw material, the alcohol can also serve as a solvent.

  0.1-30 mass% is preferable with respect to the solvent which exists in a reactor, and the density | concentration of a raw material has more preferable 0.5-20 mass%.

  The amount of molecular oxygen used is preferably 0.1 to 20 mol, more preferably 0.2 to 15 mol, and still more preferably 0.3 to 10 mol with respect to 1 mol of the raw material.

  The catalyst is preferably used in a state of being suspended in a reaction solution for performing a liquid phase oxidation reaction, but may be used in a fixed bed. 0.1-30 mass% is preferable with respect to the solution which exists in a reactor, and the usage-amount of a catalyst has more preferable 0.5-20 mass%, and 1-15 mass% is further more preferable.

  When the molybdenum compound is present in the reaction system in which liquid phase oxidation is performed by the method (C) described above, the molybdenum compound may be added directly to the reaction vessel, and the molybdenum compound is dissolved in all or part of the solvent. The solution may be added to the reaction vessel.

  In addition, the molybdenum compound is preferably dissolved and dispersed in a reaction solution for performing liquid phase oxidation. Due to the effects of both the molybdenum compound dissolved in the reaction solution and the molybdenum compound dispersed in the reaction solution, the productivity of the target product α, β-unsaturated carboxylic acid can be further increased. . Therefore, it is preferable to use the molybdenum compound in an amount exceeding the amount that can be dissolved in the reaction solution for performing liquid phase oxidation. For example, when molybdenum trioxide is used as the molybdenum compound and alcohol and / or water is used as the solvent, the addition amount of the molybdenum compound is preferably 0.01 to 5 parts by mass with respect to 100 parts by mass of the solvent. -1 mass part is more preferable, and 0.1-0.5 mass part is further more preferable. When heteropolymolybdic acid is used as the molybdenum compound and alcohol and / or water is used as the solvent, the addition amount of the molybdenum compound is preferably 0.005 to 0.5 parts by mass with respect to 100 parts by mass of the solvent, 0.01 -0.1 mass part is more preferable, and 0.03-0.07 mass part is further more preferable.

  The reaction temperature and reaction pressure are appropriately selected depending on the solvent and raw materials used. The reaction temperature is preferably 30 to 200 ° C, more preferably 50 to 150 ° C. The reaction pressure is preferably 0 to 10 MPa, and more preferably 0.5 to 5 MPa.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated further more concretely, this invention is not limited to an Example.

(Measurement of the molar ratio of tellurium and palladium (Te / Pd) in the catalyst)
It was calculated from the mass and atomic weight of palladium and tellurium in the catalyst. The masses of palladium and tellurium in the catalyst were measured by sequentially performing the following steps.
Preparation of treatment solution A: 0.2 g of catalyst and a predetermined amount of concentrated nitric acid, concentrated sulfuric acid, and hydrogen peroxide water were placed in a Teflon (registered trademark) decomposition tube, and a microwave thermal decomposition apparatus (CEM, product name: The dissolution treatment was performed with MARS5). The sample was filtered, and the filtrate and the washing water were combined and made up into a volumetric flask to obtain a treatment solution A.
-Preparation of B treatment liquid: The filter paper which collected the insoluble part in the preparation of the A treatment liquid was transferred to a platinum crucible, heated and incinerated, and then added with lithium metaborate and melted with a gas burner. After cooling, hydrochloric acid and a small amount of water were put in a crucible and dissolved, and then measured up in a measuring flask to obtain a B treatment solution.
-Determination of tellurium and palladium in the catalyst: The masses of palladium and tellurium contained in the obtained A treatment liquid and B treatment liquid were each quantified with an ICP emission analyzer (trade name: IRIS-Advantage, manufactured by Thermo Elemental) The total value was defined as the mass of palladium and tellurium in the catalyst, respectively.

(Analysis of raw materials and products)
Analysis of raw materials and products was performed using gas chromatography. Reaction rate of olefin used as raw material, selectivity of produced α, β-unsaturated aldehyde, α, β-unsaturated carboxylic acid and α, β-unsaturated carboxylic acid anhydride, and produced α, β-unsaturated The productivity of saturated carboxylic acid is defined as follows.
Olefin reaction rate (%) = (B / A) × 100
Selectivity of α, β-unsaturated aldehyde (%) = (C / B) × 100
Selectivity of α, β-unsaturated carboxylic acid (%) = (D / B) × 100
Selectivity of α, β-unsaturated carboxylic acid anhydride (%) = (2 × E / B) × 100
Productivity of α, β-unsaturated carboxylic acid (g / (g-Pd · h)) = F / (G × H)
Here, A is the number of moles of olefin supplied, B is the number of moles of reacted olefin, C is the number of moles of α, β-unsaturated aldehyde produced, and D is the mole of α, β-unsaturated carboxylic acid produced. Number, E is the number of moles of α, β-unsaturated carboxylic acid anhydride produced, F is the mass of the α, β-unsaturated carboxylic acid produced (unit: g), and G is Pd in the catalyst used in the reaction. Mass (unit: g), H is the reaction time (unit: h).

<Example 1>
(Manufacture of catalyst)
By dissolving 0.216 g of telluric acid in 40 g of pure water and dissolving 4.272 g of palladium nitrate solution (manufactured by NE Chemcat, Pd content 23.41 mass%) in the resulting solution, the mixed solution was dissolved. Prepared. In this mixed solution, 20 g of silica support (specific surface area 450 m ² / g, pore volume 0.68 cc / g) was added and immersed, and then evaporation was performed, whereby telluric acid and palladium nitrate were added to the silica support. Supported. Next, the silica support was calcined in air at 200 ° C. for 3 hours to obtain a catalyst precursor. This catalyst precursor was added to 60 g of a 37% by mass aqueous formaldehyde solution, and reduced at 70 ° C. for 2 hours with a hot stirrer. A catalyst (PdTe) in which palladium and tellurium were supported on a silica support was obtained through suction filtration and washing with pure water. Te / Pd of the obtained catalyst was 0.10, the palladium loading was 5.0% by mass, and the tellurium loading was 0.6% by mass.

(Reaction evaluation)
In an autoclave with an internal volume of 300 ml, 10.56 g of the above catalyst (corresponding to 0.5 g of Pd), 100 g of an 86 mass% t-butanol aqueous solution as a reaction solvent, 0.1 g of molybdenum trioxide as a molybdenum compound, p-methoxyphenol, 0.1%. 02 g was charged and the autoclave was sealed. Next, 6.5 g of isobutylene was introduced into the autoclave, and the temperature was raised to 110 ° C. while stirring at a rotation speed of 1000 rpm. After completion of the temperature increase, nitrogen was introduced into the autoclave until the internal pressure reached 2.4 MPa, and further compressed air was introduced until the internal pressure reached 4.8 MPa to initiate the reaction. Thereafter, when the internal pressure was reduced to 0.2 MPa and reached 4.6 MPa, the operation of introducing oxygen until the internal pressure reached 4.8 MPa was repeated 10 times, and the internal pressure was further reduced by 0.2 MPa to 4.6 MPa. The reaction was terminated at the time. The reaction time was 16 minutes.

  After completion of the reaction, the inside of the autoclave was cooled with an ice bath. A gas collection bag was attached to the gas outlet of the autoclave, and the gas outlet was opened. The pressure in the reactor was released while collecting the gas coming out from the gas outlet. The reaction solution containing the catalyst was taken out from the autoclave, the catalyst was separated by a membrane filter, and the reaction solution was recovered. The collected reaction liquid and the collected gas were analyzed by gas chromatography, and the reaction rate, selectivity and productivity were calculated. The results are shown in Table 1.

<Example 2>
A catalyst was produced in the same manner as in Example 1. Moreover, reaction evaluation was performed by the method similar to Example 1 except having changed the usage-amount of molybdenum trioxide into 0.3g. The results are shown in Table 1.

<Example 3>
A catalyst was produced in the same manner as in Example 1. Moreover, reaction evaluation was performed by the method similar to Example 1 except having changed the usage-amount of molybdenum trioxide into 0.5 g. The results are shown in Table 1.

<Example 4>
A catalyst was produced in the same manner as in Example 1. In addition, 0.05 g of phosphomolybdic acid n-hydrate (manufactured by Wako Pure Chemical Industries, 12 molybdo (VI) phosphoric acid n-hydrate, H ₃ (PMo ₁₂ O ₄₀ ) nH ₂ O) was used as the molybdenum compound. The reaction was evaluated in the same manner as in Example 1. The results are shown in Table 1.

<Example 5>
A catalyst was produced in the same manner as in Example 1. Moreover, silicomolybdic acid n-hydrate (manufactured by Wako Pure Chemical Industries, 12 molybdosilicic acid n-hydrate, H ₄ [Si (Mo ₃ O ₁₀ ) ₄ ] nH ₂ O) 0.05 g was used as the molybdenum compound. Except for the above, reaction evaluation was performed in the same manner as in Example 1. The results are shown in Table 1.

<Comparative Example 1>
A catalyst was produced in the same manner as in Example 1. Moreover, reaction evaluation was performed by the method similar to Example 1 except not having used a molybdenum compound. The results are shown in Table 1.

<Comparative Example 2>
A catalyst (Pd) in which palladium was supported on a silica carrier was produced in the same manner as in Example 1 except that telluric acid was not used. The palladium loading rate of the obtained catalyst was 5.0% by mass. Moreover, reaction evaluation was performed by the method similar to the comparative example 1 except having used this catalyst. The results are shown in Table 1.

<Comparative Example 3>
A catalyst was produced in the same manner as in Comparative Example 2. Moreover, reaction evaluation was performed by the method similar to Example 1 except having used this catalyst. The results are shown in Table 1.

<Comparative example 4>
A catalyst was produced in the same manner as in Comparative Example 2. Moreover, reaction evaluation was performed by the method similar to Example 2 except having used this catalyst. The results are shown in Table 1.

<Comparative Example 5>
A catalyst was produced in the same manner as in Comparative Example 2. Moreover, reaction evaluation was performed by the same method as Example 3 except having used this catalyst. The results are shown in Table 1.

<Comparative Example 6>
A catalyst was produced in the same manner as in Comparative Example 2. Moreover, reaction evaluation was performed by the method similar to Example 4 except having used this catalyst. The results are shown in Table 1.

<Comparative Example 7>
(Manufacture of catalyst)
After adding 20 g of silica support (specific surface area 450 m ² / g, pore volume 0.68 cc / g) in a solution of 1.065 g of lead (II) dissolved in 40 g of pure water, evaporation As a result, lead (II) acetate was supported on the silica support. Subsequently, this silica carrier was calcined in air at 500 ° C. for 3 hours. Moreover, the silica support which carried out the said process was added and immersed in the solution which melt | dissolved 4.272 g of palladium nitrate solutions (the product made from NE Chemcat, Pd content rate 23.41 mass%) in 40 g of pure waters. Thereafter, evaporation was performed to support palladium nitrate on the silica carrier. Next, the silica support was calcined in air at 200 ° C. for 3 hours to obtain a catalyst precursor. This catalyst precursor was added to 60 g of a 37% by mass aqueous formaldehyde solution, and reduced at 70 ° C. for 2 hours with a hot stirrer. A catalyst (PdPb) in which palladium and lead were supported on a silica carrier was obtained through suction filtration and washing with pure water. The obtained catalyst had a Pb / Pd of 0.30, a palladium loading ratio of 5.0 mass%, and a lead loading ratio of 2.9 mass%.

(Reaction evaluation)
The reaction was evaluated in the same manner as in Example 3 except that this catalyst was used. The reaction was completed in 30 minutes because of a slow decrease in the reaction pressure. The amount of additional oxygen introduced was 0.4 MPa. The results are shown in Table 1.

  As described above, the presence of the molybdenum compound in the liquid phase oxidation reaction system using the catalyst containing palladium and tellurium allows the target product α, β- to be compared with the case of using another catalyst. It was found that the productivity of unsaturated carboxylic acid was specifically increased.

Claims (5)

  A process for producing an α, β-unsaturated carboxylic acid by liquid phase oxidation of alcohol, olefin or α, β-unsaturated aldehyde with molecular oxygen in the presence of a catalyst containing palladium and tellurium, A process for producing an α, β-unsaturated carboxylic acid, characterized in that a molybdenum compound is present therein.   The method for producing an α, β-unsaturated carboxylic acid according to claim 1, wherein palladium and tellurium in the catalyst are supported on a support.   The method for producing an α, β-unsaturated carboxylic acid according to claim 1 or 2, wherein the molybdenum compound is supported on the catalyst.   The method for producing an α, β-unsaturated carboxylic acid according to claim 2, wherein the molybdenum compound is supported on the carrier.   The method for producing an α, β-unsaturated carboxylic acid according to claim 1 or 2, wherein the molybdenum compound is present in a dissolved and / or dispersed state in the reaction solution.