CN115947653A - Method and catalyst for simultaneously producing 1, 4-cyclohexanedicarboxylic acid as byproduct in hydrofining of crude terephthalic acid - Google Patents

Method and catalyst for simultaneously producing 1, 4-cyclohexanedicarboxylic acid as byproduct in hydrofining of crude terephthalic acid Download PDF

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CN115947653A
CN115947653A CN202111171900.9A CN202111171900A CN115947653A CN 115947653 A CN115947653 A CN 115947653A CN 202111171900 A CN202111171900 A CN 202111171900A CN 115947653 A CN115947653 A CN 115947653A
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catalyst
acid
terephthalic acid
activated carbon
reaction
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朱庆才
张海涛
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China Petroleum and Chemical Corp
Sinopec Shanghai Research Institute of Petrochemical Technology
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China Petroleum and Chemical Corp
Sinopec Shanghai Research Institute of Petrochemical Technology
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Abstract

The invention provides a method and a catalyst for simultaneously producing 1, 4-cyclohexanedicarboxylic acid as a byproduct in the hydrofining of crude terephthalic acid. The method comprises the following steps: mixing crude terephthalic acid, a catalyst and a solvent; (2) Carrying out hydrofining reaction at the temperature of 250-285 ℃ and the pressure of 6-10MPa to obtain purified terephthalic acid and 1, 4-cyclohexanedicarboxylic acid; wherein the catalyst comprises a carrier and Pd and Rh supported on the carrier. The invention realizes the byproduct 1, 4-cyclohexanedicarboxylic acid (CHDA) in the process of preparing Purified Terephthalic Acid (PTA) by hydrofining Crude Terephthalic Acid (CTA). In particular, the selection of a specific catalyst to match the appropriate reaction conditions not only eliminates the need for a new CHDA production facility, but also maximizes the economic efficiency of the facility.

Description

Method and catalyst for simultaneously producing 1, 4-cyclohexanedicarboxylic acid as byproduct in hydrofining of crude terephthalic acid
Technical Field
The invention relates to a hydrofining technology of crude terephthalic acid, in particular to a method for hydrofining crude terephthalic acid and simultaneously producing 1, 4-cyclohexanedicarboxylic acid as a byproduct and a catalyst thereof.
Background
Purified Terephthalic Acid (PTA) is an important organic chemical raw material. Usually, crude Terephthalic Acid (CTA) is obtained by liquid-phase oxidation of Paraxylene (PX), and the crude terephthalic acid is obtained by hydrorefining CTA. CTA generally contains a relatively high amount of p-carboxybenzaldehyde (4-CBA), the purification process is mainly for removing 4-CBA, and the industry generally requires that the content of 4-CBA in PTA is less than 25ppm.
1, 4-cyclohexanedicarboxylic acid (CHDA) is an aliphatic dibasic acid, and is mainly used as a modified monomer for producing resin for powder coating, high-solid-content melamine (melamine) polyester baking enamel, resin for coil coating, water-based polyester resin, unsaturated polyester resin for gel coat coating, unsaturated polyester resin for gel soil layer and polyester polyol for polyurethane coating.
In addition to being a modifying monomer, CHDA is an intermediate for the production of 1, 4-Cyclohexanedimethanol (CHDM), which is an industrially important raw material for polyester production, primarily for the production of polyester fibers. Compared with the polyester synthesized by ethylene glycol, the polyester fiber produced by CHDM not only has the characteristics of low density, high melting point and the like, but also has excellent hydrolytic stability and electrical performance, and is particularly suitable for manufacturing electrical equipment. At present, enterprises for realizing industrial production of CHDA globally are mainly represented by American Eastman chemical company, and in addition, american Amoco company and Japanese Towa chemical industry Co., ltd. Have research and development of related technologies of CHDA.
As early as 1959, the best method for preparing CHDA from terephthalic acid is proposed in U.S. Pat. No. 5,88484 (the best example of which is shown in the following description), which uses palladium-based catalyst for hydrogenation of terephthalic acid, wherein the reaction temperature is 195 deg.C, the reaction pressure is higher than 34MPa, the conversion rate of terephthalic acid after 2h reaction reaches 100%, and the yield of 1, 4-cyclohexanedicarboxylic acid reaches 98.5%, thus obtaining good results, but the reaction pressure is too high, and the method is difficult to implement. U.S. Pat. No. 5,5430184 discloses a process for preparing 1, 4-cyclohexanedicarboxylic acid, but using ethanol and water as solvents to increase the feed concentration of terephthalic acid solution, and also using palladium catalyst with palladium loading of 5% -10% and acid-resistant material such as aluminum, silicon or carbon as carrier. Under the conditions of hydrogenation reaction temperature of 120-160 ℃ and pressure of 0.19-0.95 MPa, the reaction time is 30-120 min, the purity of CHDA products is analyzed to reach 98% after the catalyst is filtered off, and byproducts mainly comprise 4-methyl cyclohexane carboxylic acid and cyclohexane carboxylic acid. Although the reaction temperature and the reaction pressure are reduced, the system introduces ethanol, so that a plurality of byproducts are generated and the separation is difficult.
U.S. Pat. No. 6291706 discloses a process for hydrogenating terephthalic acid to 1, 4-cyclohexanedicarboxylic acid, which in the examples provided therein utilizes a 0.5wt% Pd/C catalyst, the mass fraction of phthalic acid in aqueous solution is 5%, the purity of the hydrogenation product CHDA reaches up to 98% at a temperature in the range of 200 to 230 ℃ and a hydrogen pressure of 4.48MPa, but the conversion of Terephthalic Acid (TA) is only 66.5%.
Since the demand for CHDA is not so high in the industry, the preparation of CHDA in a single plant is not economical in industrial production. It would be an economical and effective means to produce CHDA as a byproduct in the process of PTA production from CTA purification. However, because there is a clear contradiction between the process of preparing PTA by CTA refining and the process of preparing CHDA by CTA, the reaction temperature of CTA hydrofining is above 280 ℃, and if TA is hydrogenated to CHDA at this temperature, severe decarboxylation will occur and a large amount of cyclohexanecarboxylic acid will be generated, which affects the yield of CHDA. However, if the reaction is carried out at 250 ℃, the TA solubility is low, which greatly reduces the efficiency of CTA hydrofining, and thus the capacity of the apparatus cannot be effectively utilized.
Disclosure of Invention
The invention aims to provide a method and a catalyst for preparing 1, 4-cyclohexanedicarboxylic acid (CHDA) as a byproduct in the process of preparing Purified Terephthalic Acid (PTA) by hydrofining Crude Terephthalic Acid (CTA). So as to realize the byproduct CHDA in the process of preparing PTA by refining CTA.
The first aspect of the present invention provides a method for simultaneously hydrorefining crude terephthalic acid and producing 1, 4-cyclohexanedicarboxylic acid as a by-product, comprising the steps of:
(1) Mixing crude terephthalic acid, a catalyst and a solvent;
(2) Carrying out hydrofining reaction at the temperature of 250-285 ℃ and the pressure of 6-10MPa to obtain purified terephthalic acid and 1, 4-cyclohexanedicarboxylic acid;
wherein the catalyst comprises a carrier and Pd and Rh supported on the carrier.
Further, the load amount of Pd in the catalyst is 0.5wt% -1wt%, and the load amount of Rh is 0.1wt% -0.5wt%.
Further, the carrier is activated carbon, preferably coconut shell activated carbon, more preferably the specific surface area of the coconut shell activated carbon is 800-1200m 2 The sum of the contents of Na, K and Ca in the activated carbon is not higher than 300ppm.
Further, the mass ratio of the crude terephthalic acid to the solvent in the step (1) is 1:99-30:70, the mass ratio of the crude terephthalic acid to the catalyst is 100: (1-10).
Further, the solvent in step (1) is preferably water.
Further, the crude terephthalic acid in step (1) contains 0.1-0.35 wt% of 4-formyl-benzoic acid.
Further, the reaction time in the step (2) is controlled to be 15-90min.
Further, the step (2) is followed by a separation step, wherein the separation step comprises filtering the reaction mixture at 80-160 ℃ to obtain purified terephthalic acid, cooling the obtained filtrate to 5-20 ℃ and then filtering to obtain the 1, 4-cyclohexanedicarboxylic acid.
The second aspect of the present invention is to provide a catalyst for simultaneously producing 1, 4-cyclohexanedicarboxylic acid as a by-product by hydrorefining crude terephthalic acid, which comprises a carrier and Pd and Rh supported on the carrier.
Further, the load amount of Pd in the catalyst is 0.5wt% -1wt%, and the load amount of Rh is 0.1wt% -0.5wt%.
Further, the carrier is activated carbon, preferably coconut shell activated carbon, more preferably the specific surface area of the coconut shell activated carbon is 800-1200m 2 The sum of the contents of Na, K and Ca in the activated carbon is not higher than 300ppm.
The invention realizes the byproduct 1, 4-cyclohexanedicarboxylic acid (CHDA) in the process of preparing Purified Terephthalic Acid (PTA) by hydrofining Crude Terephthalic Acid (CTA). The by-product CHDA in the invention means that the content of CHDA in the product is at least more than 5wt%. In particular, the selection of a specific catalyst is matched with the appropriate reaction conditions, so that not only is a new CHDA production device not needed, but also the economic benefit of the device can be improved to the greatest extent.
Detailed Description
The present invention is described below by way of example with reference to specific embodiments, but it should be understood that the scope of the present invention is not limited to the specific embodiments.
The invention analyzes the metal content by adopting ICP-AES.
The analysis of the reaction products was mainly carried out by liquid chromatography by an external standard method.
[ example 1 ] A method for producing a polycarbonate
Preparation of the catalyst: 100g of coconut shell activated carbon (supplied by Nanjing Mulinson activated carbon Co., ltd., specific surface area of 1108 m) was taken 2 138ppm Na, 53ppm K and 73ppm Ca) as a carrier, 50g of mixed solution of chloropalladic acid and chlororhodic acid, 0.375g of palladium and 0.075g of rhodium as impregnation liquid, impregnating 100g of activated carbon in the impregnation liquid with continuous stirring, aging the mixed solution of chloropalladic acid and chlororhodic acid at 80 ℃ for 4 hours after the mixed solution of chloropalladic acid and chlororhodic acid is completely absorbed by the activated carbon, adding a reducing agent hydrazine hydrate for reduction after the aging is finished, washing the catalyst with deionized water until no chloride ion is detected after the reduction is finished, and finally drying the catalyst at 80 ℃ for 2 hours, wherein the Pd content of the catalyst is 0.75wt% and the Rh content is 0.15wt% by adopting ICP-AES analysis.
Hydrogenation of crude terephthalic acid: putting 10g of the catalyst into a cradle in a reaction kettle, adding 300g of crude terephthalic acid (containing 0.9g of 4-CBA) and 700g of water into the reaction kettle, starting stirring, heating to 280 ℃, controlling the pressure of the reaction kettle to be 8MPa, putting the cradle into a reaction solution when the temperature and the pressure meet the requirements, introducing hydrogen for reaction for 25min, cooling the temperature of the reaction kettle to room temperature after the reaction is finished, taking out a reaction product, sampling after ammonia is completely dissolved, and performing liquid chromatography to analyze the CHDA content of the 4-CBA content and the decarboxylation product (benzoic acid and cyclohexanecarboxylic acid) content. For convenience of comparison, the analysis results are listed in table 1.
[ example 2 ]
Preparation of the catalyst: 100g of coconut shell activated carbon (supplied by Nanjing Mulinson activated carbon Co., ltd., specific surface area of 1108 m) was taken 2 138ppm Na, 53ppm K and 73ppm Ca) as a carrier, 50g of mixed solution of chloropalladic acid and chlororhodic acid, 0.25g of palladium and 0.175g of rhodium as impregnation liquid, impregnating 100g of activated carbon in the impregnation liquid with continuous stirring, aging the mixed solution of chloropalladic acid and chlororhodic acid at the temperature of 80 ℃ for 4h after the mixed solution of chloropalladic acid and chlororhodic acid is completely absorbed by the activated carbon, adding a reducing agent hydrazine hydrate for reduction after the aging is finished, washing the catalyst with deionized water until no chloride ion is detected after the reduction is finished, and finally drying the catalyst at the temperature of 80 ℃ for 2h, wherein the Pd content of the catalyst is 0.5wt% by adopting ICP-AES analysis, and the Rh content is 0.35wt%.
Hydrogenation of crude terephthalic acid: putting 10g of the catalyst into a hanging basket in a reaction kettle, adding 300g of crude terephthalic acid (containing 0.9g of 4-CBA) and 700g of water into the reaction kettle, starting stirring, heating to 280 ℃, controlling the pressure of the reaction kettle to be 8MPa, putting the hanging basket of the catalyst into a reaction solution when the temperature and the pressure meet the requirements, introducing hydrogen for reaction for 25min, cooling the temperature of the reaction kettle to room temperature after the reaction is finished, taking out a reaction product, sampling after completely dissolving ammonia water, and analyzing the content of 4-CBA (CHDA) and the content of decarboxylation products (benzoic acid and cyclohexanecarboxylic acid) in the reaction solution by liquid chromatography. For convenience of comparison, the analysis results are listed in table 1.
[ example 3 ]
Preparation of the catalyst: get100g of coconut shell activated carbon (available from Nanjing Mulinson activated carbon Co., ltd., specific surface area of 1108 m) 2 138ppm Na, 53ppm K and 73ppm Ca) as a carrier, 50g of mixed solution of chloropalladic acid and chlororhodic acid, 0.5g of palladium and 0.05g of rhodium as impregnation liquid, impregnating 100g of activated carbon in the impregnation liquid with continuous stirring, aging the mixed solution of chloropalladic acid and chlororhodic acid at the temperature of 80 ℃ for 4h after the mixed solution of chloropalladic acid and chlororhodic acid is completely absorbed by the activated carbon, adding a reducing agent hydrazine hydrate for reduction after the aging is finished, washing the catalyst with deionized water until no chloride ion is detected after the reduction is finished, and finally drying the catalyst at the temperature of 80 ℃ for 2h, wherein the Pd content of the catalyst is 1.0wt% and the Rh content is 0.1wt% by adopting ICP-AES analysis.
Hydrogenation of crude terephthalic acid: putting 10g of the catalyst into a hanging basket in a reaction kettle, adding 300g of crude terephthalic acid (containing 0.9g of 4-CBA) and 700g of water into the reaction kettle, starting stirring, heating to 280 ℃, controlling the pressure of the reaction kettle to be 8MPa, putting the hanging basket of the catalyst into a reaction solution when the temperature and the pressure meet the requirements, introducing hydrogen for reaction for 25min, cooling the temperature of the reaction kettle to room temperature after the reaction is finished, taking out a reaction product, sampling after completely dissolving ammonia water, and analyzing the content of 4-CBA (CHDA) and the content of decarboxylation products (benzoic acid and cyclohexanecarboxylic acid) in the reaction solution by liquid chromatography. For comparison, the analysis results are listed in table 1.
[ example 4 ]
Preparation of the catalyst: 100g of coconut shell activated carbon (supplied by Nanjing Mulinson activated carbon Co., ltd., specific surface area of 1108 m) was taken 2 138ppm Na, 53ppm K and 73ppm Ca) as a carrier, 50g of mixed solution of chloropalladic acid and chlororhodic acid, 0.35g of palladium and 0.25g of rhodium as impregnation liquid, impregnating 100g of activated carbon in the impregnation liquid with continuous stirring, aging the mixed solution of chloropalladic acid and chlororhodic acid at the temperature of 80 ℃ for 4 hours after the mixed solution of chloropalladic acid and chlororhodic acid is completely absorbed by the activated carbon, adding a reducing agent hydrazine hydrate for reduction after the aging is finished, washing the catalyst with deionized water until no chloride ion is detected after the reduction is finished, and finally drying the catalyst at the temperature of 80 ℃ for 2 hours, wherein the Pd content of the catalyst is 0.7wt% and the Rh content is 0.5wt% by adopting ICP-AES analysis.
Hydrogenation of crude terephthalic acid: putting 10g of the catalyst into a hanging basket in a reaction kettle, adding 300g of crude terephthalic acid (containing 0.9g of 4-CBA) and 700g of water into the reaction kettle, starting stirring, heating to 280 ℃, controlling the pressure of the reaction kettle to be 8MPa, putting the hanging basket of the catalyst into a reaction solution when the temperature and the pressure meet the requirements, introducing hydrogen for reaction for 25min, cooling the temperature of the reaction kettle to room temperature after the reaction is finished, taking out a reaction product, sampling after completely dissolving ammonia water, and analyzing the content of 4-CBA (CHDA) and the content of decarboxylation products (benzoic acid and cyclohexanecarboxylic acid) in the reaction solution by liquid chromatography. For convenience of comparison, the analysis results are listed in table 1.
[ example 5 ]
Preparation of the catalyst: 100g of coconut shell activated carbon (supplied by Nanjing Loranton activated carbon Co., ltd., specific surface area 1108 m) was taken 2 138ppm Na, 53ppm K and 73ppm Ca) as a carrier, 50g of mixed solution of chloropalladic acid and chlororhodic acid, 0.375g of palladium and 0.075g of rhodium as impregnation liquid, impregnating 100g of activated carbon in the impregnation liquid with continuous stirring, aging the mixed solution of chloropalladic acid and chlororhodic acid at 80 ℃ for 4 hours after the mixed solution of chloropalladic acid and chlororhodic acid is completely absorbed by the activated carbon, adding a reducing agent hydrazine hydrate for reduction after the aging is finished, washing the catalyst with deionized water until no chloride ion is detected after the reduction is finished, and finally drying the catalyst at 80 ℃ for 2 hours, wherein the Pd content of the catalyst is 0.75wt% and the Rh content is 0.15wt% by adopting ICP-AES analysis.
Hydrogenation of crude terephthalic acid: putting 10g of the catalyst into a hanging basket in a reaction kettle, adding 125g of crude terephthalic acid (containing 4-CBA in an amount of 0.375 g) and 2375g of water into the reaction kettle, then starting stirring and heating to 265 ℃, controlling the pressure of the reaction kettle to be 10MPa, putting the hanging basket of the catalyst into a reaction solution when the temperature and the pressure meet the requirements, simultaneously introducing hydrogen for reaction for 60min, cooling the temperature of the reaction kettle to room temperature after the reaction is finished, taking out a reaction product, sampling after completely dissolving ammonia water, and analyzing the content of the 4-CBA (CHDA) and the content of the decarboxylation product (benzoic acid and cyclohexanecarboxylic acid) in the reaction solution by liquid chromatography. For comparison, the analysis results are listed in table 1.
[ example 6 ]
Preparation of the catalyst: 100g of coconut shell activated carbon (supplied by Nanjing Mulinson activated carbon Co., ltd., specific surface area of 1108 m) was taken 2 138ppm Na, 53ppm K and 73ppm Ca) as a carrier, 50g of mixed solution of chloropalladic acid and chlororhodic acid, 0.375g of palladium and 0.075g of rhodium as impregnation liquid, impregnating 100g of activated carbon in the impregnation liquid with continuous stirring, aging the mixed solution of chloropalladic acid and chlororhodic acid at 80 ℃ for 4 hours after the mixed solution of chloropalladic acid and chlororhodic acid is completely absorbed by the activated carbon, adding a reducing agent hydrazine hydrate for reduction after the aging is finished, washing the catalyst with deionized water until no chloride ion is detected after the reduction is finished, and finally drying the catalyst at 80 ℃ for 2 hours, wherein the Pd content of the catalyst is 0.75wt% and the Rh content is 0.15wt% by adopting ICP-AES analysis.
Hydrogenation of crude terephthalic acid: putting 10g of the catalyst into a cradle in a reaction kettle, adding 100g of crude terephthalic acid (containing 0.3g of 4-CBA) and 900g of water into the reaction kettle, starting stirring, heating to 280 ℃, controlling the pressure of the reaction kettle to be 8MPa, putting the cradle into a reaction solution when the temperature and the pressure meet the requirements, introducing hydrogen for reaction for 25min, cooling the temperature of the reaction kettle to room temperature after the reaction is finished, taking out a reaction product, sampling after ammonia is completely dissolved, and analyzing the CHDA content of the 4-CBA content and the decarboxylation product (benzoic acid + cyclohexanecarboxylic acid) content by liquid chromatography. For convenience of comparison, the analysis results are listed in table 1.
[ example 7 ]
Preparation of the catalyst: 100g of coconut shell activated carbon (supplied by Nanjing Loranton activated carbon Co., ltd., specific surface area 1108 m) was taken 2 138ppm Na, 53ppm K and 73ppm Ca) as a carrier, 50g of mixed solution of chloropalladic acid and chlororhodic acid, 0.375g of palladium and 0.075g of rhodium as impregnation liquid, impregnating 100g of activated carbon in the impregnation liquid with continuous stirring, aging the mixed solution of chloropalladic acid and chlororhodic acid at the temperature of 80 ℃ for 4 hours after the mixed solution of chloropalladic acid and chlororhodic acid is completely absorbed by the activated carbon, adding a reducing agent hydrazine hydrate for reduction, cleaning the mixture with deionized water after the reduction is finished, and drying the mixtureThe catalyst is dried for 2 hours at 80 ℃ until no chloride ion is detected, and the catalyst is analyzed by ICP-AES, wherein the Pd content of the catalyst is 0.75wt%, and the Rh content of the catalyst is 0.15wt%.
Hydrogenation of crude terephthalic acid: putting 10g of the catalyst into a hanging basket in a reaction kettle, adding 200g of crude terephthalic acid (containing 0.6g of 4-CBA) and 800g of water into the reaction kettle, starting stirring, heating to 280 ℃, controlling the pressure of the reaction kettle to be 8MPa, putting the hanging basket of the catalyst into a reaction solution when the temperature and the pressure meet the requirements, introducing hydrogen for reaction for 25min, cooling the temperature of the reaction kettle to room temperature after the reaction is finished, taking out a reaction product, sampling after completely dissolving ammonia water, and analyzing the content of 4-CBA (CHDA) and the content of decarboxylation products (benzoic acid and cyclohexanecarboxylic acid) in the reaction solution by liquid chromatography. For convenience of comparison, the analysis results are listed in table 1.
[ example 8 ]
Preparation of the catalyst: 100g of coconut shell activated carbon (supplied by Nanjing Mulinson activated carbon Co., ltd., specific surface area of 1108 m) was taken 2 138ppm Na, 53ppm K and 73ppm Ca) as a carrier, and 50g of mixed solution of chloropalladic acid and chlororhodic acid, 0.375g of palladium and 0.075g of rhodium as impregnation liquid, impregnating 100g of activated carbon in the impregnation liquid, continuously stirring, aging for 4 hours at the temperature of 80 ℃ after the mixed solution of chloropalladic acid and chlororhodic acid is completely absorbed by the activated carbon, adding a reducing agent hydrazine hydrate for reduction, washing the catalyst with deionized water after the reduction is finished until no chloride ion is detected, and finally drying the catalyst for 2 hours at the temperature of 80 ℃, wherein the Pd content of the catalyst is 0.75wt% by adopting ICP-AES analysis, and the Rh content is 0.15wt%.
Hydrogenation of crude terephthalic acid: putting 10g of the catalyst into a hanging basket in a reaction kettle, adding 300g of crude terephthalic acid (containing 0.9g of 4-CBA) and 700g of water into the reaction kettle, starting stirring, heating to 250 ℃, controlling the pressure of the reaction kettle to be 6MPa, putting the hanging basket of the catalyst into a reaction solution when the temperature and the pressure meet the requirements, introducing hydrogen for reaction for 90min, cooling the temperature of the reaction kettle to room temperature after the reaction is finished, taking out a reaction product, sampling after completely dissolving ammonia water, and analyzing the content of 4-CBA (CHDA) and the content of decarboxylation products (benzoic acid and cyclohexanecarboxylic acid) in the reaction solution by liquid chromatography. For convenience of comparison, the analysis results are listed in table 1.
[ example 9 ]
Preparation of the catalyst: 100g of coconut shell activated carbon (available from Nanjing Mulinson activated carbon Co., ltd., specific surface area 1135 m) 2 207ppm of Na, 132ppm of K and 18ppm of Ca) as a carrier, soaking 100g of activated carbon in 50g of mixed solution of chloropalladic acid and chlororhodic acid, wherein the palladium content is 0.375g, and the rhodium content is 0.075g as a soaking solution, continuously stirring, after the mixed solution of chloropalladic acid and chlororhodic acid is completely absorbed by the activated carbon, aging for 4h at the temperature of 80 ℃, adding a reducing agent hydrazine hydrate for reduction, washing the catalyst with deionized water after the reduction is finished until no chloride ion is detected, and finally drying the catalyst for 2h at the temperature of 80 ℃, wherein the Pd content of the catalyst is 0.75wt% and the Rh content is 0.15wt% by adopting ICP-AES analysis.
Hydrogenation of crude terephthalic acid: putting 10g of the catalyst into a cradle in a reaction kettle, adding 300g of crude terephthalic acid (containing 0.9g of 4-CBA) and 700g of water into the reaction kettle, starting stirring, heating to 280 ℃, controlling the pressure of the reaction kettle to be 8MPa, putting the cradle into a reaction solution when the temperature and the pressure meet the requirements, introducing hydrogen for reaction for 25min, cooling the temperature of the reaction kettle to room temperature after the reaction is finished, taking out a reaction product, sampling after ammonia is completely dissolved, and performing liquid chromatography to analyze the CHDA content of the 4-CBA content and the decarboxylation product (benzoic acid and cyclohexanecarboxylic acid) content. For convenience of comparison, the analysis results are listed in table 1.
[ COMPARATIVE EXAMPLE 1 ]
Preparation of the catalyst: 100g of coconut shell activated carbon (supplied by Nanjing Mulinson activated carbon Co., ltd., specific surface area of 1108 m) was taken 2 138ppm Na, 53ppm K and 73ppm Ca) as a carrier, 50g of a chloropalladate solution containing 0.45g of palladium as an impregnation solution, 100g of activated carbon as an impregnation solution, stirring the solution continuously, after the chloropalladate solution has been completely absorbed by the activated carbon, aging the solution at 80 ℃And (3) dissolving for 4h, adding a reducing agent hydrazine hydrate for reduction after aging is finished, washing the catalyst by using deionized water until no chloride ion is detected after reduction is finished, and finally drying the catalyst for 2h at 80 ℃, wherein the Pd content of the catalyst is 0.9wt% by adopting ICP-AES analysis.
Hydrogenation of crude terephthalic acid: putting 10g of the catalyst into a hanging basket in a reaction kettle, adding 300g of crude terephthalic acid (containing 0.9g of 4-CBA) and 700g of water into the reaction kettle, starting stirring, heating to 280 ℃, controlling the pressure of the reaction kettle to be 8MPa, putting the hanging basket of the catalyst into a reaction solution when the temperature and the pressure meet the requirements, introducing hydrogen for reaction for 25min, cooling the temperature of the reaction kettle to room temperature after the reaction is finished, taking out a reaction product, sampling after completely dissolving ammonia water, and analyzing the content of 4-CBA, the content of CHDA and the content of decarboxylation products (benzoic acid and cyclohexanecarboxylic acid) by liquid chromatography. For convenience of comparison, the analysis results are listed in table 1.
[ COMPARATIVE EXAMPLE 2 ]
Preparation of the catalyst: 100g of coconut shell activated carbon (supplied by Nanjing Mulinson activated carbon Co., ltd., specific surface area of 1108 m) was taken 2 138ppm Na, 53ppm K and 73ppm Ca) as a carrier, 50g of mixed solution of chloropalladic acid and chlororuthenic acid, 0.375g of palladium and 0.075g of ruthenium as impregnation liquid, impregnating 100g of activated carbon in the impregnation liquid with continuous stirring, aging the mixed solution of chloropalladic acid and chlororuthenic acid at 80 ℃ for 4 hours after the mixed solution of chloropalladic acid and chlororuthenic acid is completely absorbed by the activated carbon, adding a reducing agent hydrazine hydrate for reduction after the aging is finished, cleaning the catalyst with deionized water until no chloride ion is detected after the reduction is finished, and finally drying the catalyst at 80 ℃ for 2 hours, wherein the Pd content of the catalyst is 0.75wt% and the Ru content is 0.15wt% by adopting ICP-AES analysis.
Hydrogenation of crude terephthalic acid: putting 10g of the catalyst into a hanging basket in a reaction kettle, adding 300g of crude terephthalic acid (containing 0.9g of 4-CBA) and 700g of water into the reaction kettle, starting stirring, heating to 280 ℃, controlling the pressure of the reaction kettle to be 8MPa, putting the hanging basket of the catalyst into a reaction solution when the temperature and the pressure meet the requirements, introducing hydrogen for reaction for 25min, cooling the temperature of the reaction kettle to room temperature after the reaction is finished, taking out a reaction product, sampling after completely dissolving ammonia water, and analyzing the content of 4-CBA (CHDA) and the content of decarboxylation products (benzoic acid and cyclohexanecarboxylic acid) in the reaction solution by liquid chromatography. For convenience of comparison, the analysis results are listed in table 1.
TABLE 1
Figure BDA0003293651340000091
The specific embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of various technical features in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.

Claims (10)

1. A method for simultaneously producing 1, 4-cyclohexanedicarboxylic acid as a byproduct in the hydrofining of crude terephthalic acid is characterized by comprising the following steps:
(1) Mixing crude terephthalic acid, a catalyst and a solvent;
(2) Carrying out hydrofining reaction at the temperature of 250-285 ℃ and the pressure of 6-10MPa to obtain purified terephthalic acid and 1, 4-cyclohexanedicarboxylic acid;
wherein the catalyst comprises a carrier and Pd and Rh supported on the carrier.
2. The process of claim 1, wherein the catalyst has a Pd loading of 0.5 wt.% to 1 wt.% and Rh loading of 0.1 wt.% to 0.5 wt.%, based on the catalyst.
3. The process according to claim 1 or 2, characterized in that the support is activated carbon, preferably coconut shell activated carbon, more preferably the coconut shell activated carbon has a specific surface area of 800-1200m 2 Per g, the sum of the contents of Na, K and Ca in the active carbon is not highAt 300ppm.
4. The process according to claim 1, wherein the mass ratio of the crude terephthalic acid to the solvent in step (1) is 1:99-30:70, the mass ratio of the crude terephthalic acid to the catalyst is 100: (1-10).
5. The process according to claim 1, wherein the crude terephthalic acid in step (1) contains 0.1 to 0.35 wt.% of 4-aldehyde-benzoic acid.
6. The method according to claim 1, wherein the reaction time in the step (2) is controlled to 15 to 90min.
7. The process according to claim 1, wherein the step (2) is followed by a separation step comprising filtering the reaction mixture at 80-160 ℃ to obtain purified terephthalic acid, cooling the obtained filtrate to 5-20 ℃ and filtering to obtain 1, 4-cyclohexanedicarboxylic acid.
8. A catalyst for simultaneously producing 1, 4-cyclohexanedicarboxylic acid by hydrogenation and purification of crude terephthalic acid is characterized by comprising a carrier and Pd and Rh which are loaded on the carrier.
9. The catalyst of claim 8 wherein the catalyst has a Pd loading of 0.5 wt.% to 1 wt.% and Rh loading of 0.1 wt.% to 0.5 wt.%, based on the catalyst.
10. Catalyst according to claim 8 or 9, characterized in that the support is activated carbon, preferably coconut shell activated carbon, more preferably the coconut shell activated carbon has a specific surface area of 800-1200m 2 The sum of the contents of Na, K and Ca in the activated carbon is not higher than 300ppm.
CN202111171900.9A 2021-10-08 2021-10-08 Method and catalyst for simultaneously producing 1, 4-cyclohexanedicarboxylic acid as byproduct in hydrofining of crude terephthalic acid Pending CN115947653A (en)

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