TW200930697A - Process for hydrogenating 4-carboxybenzaldehyde to p-toluic acid - Google Patents

Abstract

A method for hydrogenating 4-carboxybenzaldehyde (4-CBA) to p-toluic acid (PT) is disclosed. p-Toluic acid can be effectively produced from 4-carboxybenzaldehyde and hydrogen in the presence of a catalyst containing silica and palladium. The said catalyst is presented in the core-shell form, in which palladium is in the core and porous silica is in the shell. Compared to the traditional Pd/C catalyst, the said core-shell catalyst exhibits higher p-toluic acid yield at the lower hydrogenating temperature and has better resistance to catalyst sintering.

Description

200930697 IX. INSTRUCTIONS OF THE INVENTION: TECHNICAL FIELD OF THE INVENTION The present invention relates to a process for hydrogenating p-carboxyphenylfurfural to p-nonyl stilbene, which is particularly relevant to the catalyst used in the hydrogenation process. [Prior Art] Purified Terephthalic Acid (hereinafter referred to as ρτΑ) is a petrochemical intermediate material, and is also the main raw material of the polyester industry, mainly used for the production of polyethylene terephthalate ( PET) and polybutylene terephthalate (PBT). Industrially produced PTA is obtained by oxidation of p-xylene (PX), but oxidation by-products such as 4-carboxybenzaldehyde (4-CBA) are more abundant, and ethylene glycol ( EG) Polymerization produces chain scission and even darkening of the color, so crude terephthalic acid (CTA) cannot be directly polymerized with ethylene glycol to prepare PET. The pure terephthalic acid process that has been commercialized at present is a two-stage process. First, an oxidation reaction is carried out to produce a target product, and then a purification reaction is carried out to remove impurities. The product produced in the oxidation plant contains a small amount of impurities that are poorly soluble in water. It needs to be purified in a pure water as a solvent in the range of 270-280 ° C and palladium/carbon (Pd/C) catalyst catalysis. Carboxybenzoquinone reacts with hydrogen (N. Pemicone, M. Cerboni, G Prelazzi, F. Pinna, G. Fagherazzi, Catalysis Today, 44 (1998) 129; F. Menegazzo, T. Fantinel, M. 200930697

Signoretto, F. Pinna, Catalysis Communications, 8 (2007) 876-879), converted to a more water-soluble compound, p-Toluic acid (PT), in subsequent crystallization and separation processes Medium, PT will be dissolved in water to remove. For reducing the hydrogenation of the impurity 4-CBA, some patents on Pd/C catalyst are as follows:

1. U.S. Patent No. 3,138,560 (Keith et al., "Process for producing Pal ladium on carbon catalysts", U.S. Patent No. 3,138,560, ENGELHARD(R) IND INC, 1964) discloses the first international use for 4-CBA. Hydrogenated Pd/C catalyst. 2. U.S. Patent No. 4,791,226 (Puskas et al. "Catalyst and process for purification of crude terephthalie acid", U.S. Patent No. 4,791,226, Amoco Coirporation, 1988.) relates to a method for purifying crude terephthalic acid and a catalyst thereof In order to support the catalytically active palladium crystallites on the porous activated carbon support, the surface area of the activated carbon particles is 2 6 〇〇 m 2 /g, and the longitudinal length of the crystallites is less than 35 A. The catalyst is prepared by reacting the active carrier with a non-aqueous solution of the palladium salt in an organic solvent in the absence of hydrogen, and the palladium salt is reduced to palladium metal crystallites in the support. U.S. Patent No. 4,421,676 (Puskas et al., "Process for preparation of palladium on carbon catalysts used in the purification of crude terephthalic acid", U.S. Patent No. 4,421,676, Standard Oil 6 200930697 'Company (Indiana), 19θ3) The method for preparing a pd/C catalyst in crude terephthalic acid purification is to adsorb the catalyst active palladium crystallite on the porous carbon support, the surface area of the activated carbon particles is 2 600 m 2 /g, and the longitudinal length of the crystallite is less than 35 A. The specific method is to react the carrier with NazPcKNO2)4, and Na2Pd(N〇2)4 is adsorbed on the carrier to be reduced to metal palladium, wherein Na2Pd(N〇2)4 is determined by mole ratio of sulfite to sulfonate. : 1 reaction is obtained. U.S. Patent No. 4,415,479 (Plaskas et al., "Palladium on carbon o catalyst for purification of crude terephthalic acid", U.S. Patent No. 4415479, Standard Oil Company (Indiana), 1983) relates to the purification of crude terephthalic acid. The Pd/C catalyst is prepared by the method of adsorbing the crystallites on the porous carbon support, the surface area of the activated carbon particles is 600 m2/g, the longitudinal length of the crystallites is less than 35 A, and the palladium content is less than 1.0%. The activated carbon particles are reacted with an amine solution and a salt in the presence of an organic carboxylic acid. The amine concentration is sufficient to dissolve the salt, and the m〇le ratio of the acid to the amine is 0.775. The palladium reacts with carbon to obtain a catalyst. U.S. Patent No. 6,066,589 (Malentacci et al., 'v Hydrogenatiom Catalysts, US Patent No. 6066589, Sud Chemie MT. sr 1., 2000) discloses a hydrogenation catalyst comprising supported on activated carbon. Metallic palladium, wherein less than 50 wt·% Pd is located in the surface layer of 50 "m from the surface, and the remaining pd is located in a layer of 5 〇 to 400 ym deep. 200930697 Five, two star 纟 纟 化学 化学 (Samsung Genera 1 Chemica 1 s Co., Ltd.) and Berluskov Catalyst Research Institute (Institut Kataliza Imeni GK

Boreskova Sibirskogo Otdelenia Rossiiskoi Akademii Nauk) patents of these two institutions (Romanenko et al., "Catalytic composition, method for manufacturing thereof and method for the purification of terephthalic acid", US Pat. No. 6,753,290, 2004) discloses a method for purification Catalyst composition of terephthalic acid, a preparation method thereof, and a pure Q technology of terephthalic acid. The catalyst composition for purifying terephthalic acid comprises crystals of catalytically active palladium or palladium deposited on a carbon material and at least one group of metals of the periodic table, wherein the carbon material is mesoporous like graphite The material having an average mesopore size of 4 〇 4 〇〇 A 'the intermediate pores occupies at least 总 5 of the total pore volume, and the degree of graphite-like is not less than 20%, wherein the metal crystal is distributed in a large amount of the In the material particles, so that the distance from the outer surface of the particle is equal to a distance of 1 to 3 % of its radius. G From the above description, the catalyst for hydrogenating p-carboxybenzaldehyde to p-toluic acid is a palladium/carbon (Pd/C) catalyst prepared by impregnation, while palladium/carbon The use of a catalyst for the hydrogenation of p-carboxybenzaldehyde to p-toluic acid has a problem of sintering of active sites, which causes a decrease in catalytic activity. Reducing this sintering in the literature, "I 疋 add valuable ru (ru) metal to Pd / c catalyst (Romanenko et al., Influence of ruthenium addition on sintering of carbon-supported palladium" , Applied Catalysis A: General 8 200930697 227 (2002) 117-123; Jhung et al., "Carbon-supported palladium-ruthenium catalyst for hydropurification of terephthalic acid", Applied Catalysis A: General 225 (2002) 131-139), however fresh pd-Ru/c Catalyst activity is lower than fresh

Pd/C catalyst activity. The job is the reason. This work, based on the lack of conventional technology, was carefully tested and researched to create the "method of hydrogenation of p-carboxybenzaldehyde to p-nonylbenzoic acid". The following is a brief description of the case. SUMMARY OF THE INVENTION The primary object of the present invention is to provide an improved process for the hydrogenation of thiobenzaldehyde to p-methyl benzoic acid, which comprises reacting p-carboxybenzene in the presence of a catalyst system comprising cerium oxide and palladium. Formaldehyde is hydrogenated with a gas containing hydrogen to form p-toluic acid. The catalyst system containing bismuth telluride and palladium exists in the form of a core shell, the core of the catalyst contains palladium, and the shell of the catalyst is porous ruthenium dioxide. Unexpectedly, the catalyst containing ceria and palladium has excellent hydrogenation activity and excellent yield of f-based benzoic acid, and the core-shell structure of the catalyst can reduce the traditional palladium/carbon touch. The shortcomings of medium sintering. The following examples are intended to further illustrate the method of the present invention, but such examples are intended to be illustrative only and not to limit the scope of the invention. EXAMPLES 1 - 3 Catalyst Preparation The preparation of the catalyst is divided into the following two parts. The preparation of the catalyst is similar to the step of preparing the core-shell silver cerium oxide composite in the literature (Kc Chou, CCChen, Fabrication). And characterization of ❹ silver core and porous silica shell nanocomposite materials" , Microporous and Mesoporous Materials, 98 (2007) 208-213) ° Part 1: 1. Add 692·0692 g Pd (N〇) to 3 ml of deionized water. 3) 2, mixing to make it completely dissolved. 2. Dissolve 0.255 g of poly(vinylpyrrolidone) (PVP) in the above solution and stir to dissolve completely. 3. Add 0.0692 ml of formaldehyde to the above solution at room temperature. 4. Add 184. 0184 g of sodium hydroxide and mix to dissolve completely. 5. Add 11 ml of acetone to form a black precipitate. After centrifugation, C-washing and drying, a jelly-like black blocky substance is obtained. The second part: 1. The above-mentioned black bulk material is dissolved in a solution of the following composition: 1 ml of deionized water, 0.34 ml of ammonia water, and 6.64 ml of ethanol. And ultrasonically oscillate for 3 minutes. 200930697 2. Add 0.54 liter of tetmeth〇xysil (te(6) in the above solution and stir at room temperature for 24 hours. 3. Add deionized water to centrifuge and take the solid part for 10 hours under TC. 4 · The above-mentioned dried solid is placed in a u-shaped tube, and the air is calcined under the boot for 3 hours, ie, the pay/cermet dioxide core-shell catalyst. Figure 1 is the epoch / sulphur dioxide nucleocapsid Schematic diagram of the medium. Hydrogenation reaction in a 600 ml Parr reactor, adding 1 gram of p-carboxybenzaldehyde (purchased from Alfa AeSar) and 50 ml of secondary deionized water, and then adding the palladium/cerium oxide prepared above. The core-shell catalyst 〇〇〇 35 grams of this reactor is re-passed with a force of 2 GGpsig of hydrogen, the stirring rate is GG rpm, and then heated to bring the reactor to the set temperature. After one hour of reaction, The reactor is cooled to below room temperature. The reacted solution is taken and analyzed by a high-performance liquid chromatograph (Ηρα) , to measure the molar number of p-toluic acid produced. Yield of methylbenzoic acid: yield = (p-methylbenzoic acid produced) The number of ears) / (the number of moles placed on the carboxyl group) x l 〇〇 %. The results of the nitridation reaction experiments are listed in Table 1. 11 200930697 Table 1 Example 1 Example 2 Example 3 The temperature of the hydrogenation reaction, C 180 190 200 yield of p-mercaptobenzoic acid, % 73.5 98. 1 99. 1 As can be seen from the data in Table 1, in the range of temperature 180 ° 2 ° ° C to put / dioxide dioxide core shell Catalyst catalyzed the hydrogenation reaction of the ruthenium, which has a yield of more than 70%, and the reaction temperature of 20 (TC is the best, the yield of fluorenyl benzoic acid is reached. 9 g. 1%. Comparative Example The hydrogenation catalyst used in this comparative example is a commercially available 5 wt% Pd/C catalyst supplied by Strem, the hydrogenation reaction step and other conditions are as in Examples 1-3. The description is based on the commercial Pd/C catalyst of palladium/cerium dioxide core-shell catalyst replaced by the same weight (0.0035 g). The experimental results are shown in Table 2. Table 2 Hydrogenation temperature, °C vs. methyl Yield of benzoic acid, % 200 53.74 12 200930697 It can be seen from the experimental data of Table 1 and Table 2 that the reaction temperature range is 180-200 ° C. The p-toluene core-shell catalyst (ie, the catalyst in the examples) had a p-toluic acid yield (73. 5 to 99. 1%) which was significantly higher than that of the comparative Pd/C catalyst. The yield of methylbenzoic acid (the yield was only 53.74% at a reaction temperature of 200 ° C), this result is obviously unexpected. It can be understood from the above description that the method of the present invention has a remarkable effect of improving It is indeed a new invention with great industrial value.

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Claims (1)

200930697 X. Patent application scope: 1. A method for hydrogenating p-carboxybenzaldehyde to p-nonylbenzoic acid, which comprises containing a liquid containing p-carboxybenzaldehyde in the presence of a catalyst system containing ceria and palladium. Hydrogenation is carried out with a gas containing hydrogen to form p-methylbenzoic acid. The catalyst system containing cerium oxide and palladium exists in the form of a core shell containing a core of the catalyst, and the shell of the catalyst is porous cerium oxide. ❹ 2. As claimed in the first paragraph of the patent application, the catalyst system containing the cerium oxide and the palladium is first prepared by stabilizing the palladium metal fine particles with a stabilizer and then forming the outer shell of the cerium oxide. The fine particles of palladium metal are contained therein. 3. The method of claim 2, wherein the stabilizer is a polymer, a quaternary ammonium salt, and a phenanthroline. Q 4. The method of claim 2, wherein the stabilizer is polyvinyl pyrrolidone. 5. The method of claim 2, wherein the fine particles of the palladium metal are obtained by reducing a palladium compound with a reducing agent. 6. The method of claim 2, wherein the ceria shell is formed by a sol-gel method from a ruthenium compound. 7. The method of claim 5, wherein the palladium compound is nitrate, palladium acetate, palladium acetate, palladium oxalate, palladium sulfate, ammonium palladium hydride, _chemical, 14 200930697 palladium oxide, palladium ester, Palladium sulfide, palladium nitride, palladium hydride, palladium cyanide and carbonization. 8. The method of claim 5, wherein the compound is in the form of tartaric acid. 9. The method of claim 6, wherein the hydrazine compound is a decane, a decane, a decanoic acid, a hydrazine, a decylene, a valeric acid, a hydrazine gel, a cerium acetate, a cerium oxide, Nitric oxide, citrate, polyoxane. 10. The method of claim 6, wherein the hydrazine compound is tetraethoxy hydrazine. 11. The method of claim 1, wherein the hydrogenation reaction has a temperature between 20 and 350 °C. 12. The method of claim 1, wherein the hydrogenation reaction has a temperature between 50 and 300 °C. 13. The method of claim 1, wherein the hydrogenation pressure is between atmospheric pressure and atmospheric pressure. 14. The method of claim 1, wherein the hydrogenation reaction has a pressure between atmospheric pressure and 50 atmospheres. 15