Catalyst and preparation method thereof, and preparation method of 1, 4-cyclohexanedimethanol

Abstract

The invention relates to the technical field of fine chemical engineering, in particular to a catalyst, a preparation method of the catalyst and a preparation method of 1, 4-cyclohexanedimethanol. The catalyst comprises Pd, Co and a carrier; wherein in terms of the total mass of the catalyst, the content of Pd is 0.2 to 0.5 wt%, the content of Co is 0.12 to 0.3 wt%, and the content of the carrier is 99.2 to 99.68 wt%; the carrier is a mixed oxide of Al, Si and B, and the molar ratio of Al to Si to B is (3.4-4.2): 1: (0.2-0.3). According to the catalyst provided by the invention, the carbon monoxide poisoning resistance of the catalyst can be remarkably improved on the premise of reducing the content of the Pd element and the Co element, and the catalyst has the advantages of high DMT conversion rate and DMCD selectivity.

Description

Technical Field

[0001] The invention relates to the technical field of fine chemical industry, and in particular to a catalyst and a preparation method thereof, and a preparation method of 1,4-cyclohexanedimethanol. Background Art

[0002] PETG is a transparent, non-crystalline copolyester. PETG is the product of terephthalic acid (PDA), ethylene glycol (EG) and 1,4-cyclohexanedimethanol (CHDM) by ester exchange. Unlike PET and PCT materials, PETG has outstanding toughness and high impact strength. Its impact strength is 3 to 10 times that of modified polyacrylates. It has a wide processing range, high mechanical strength and excellent flexibility. Compared with PVC, it has high transparency, good gloss, easy printing and environmental protection advantages.

[0003] At present, the preparation of PETG's important monomer 1,4-cyclohexanedimethanol (CHDM) mainly adopts the two-step hydrogenation route of dimethyl terephthalate (DMT). In the first step, the DMT benzene ring is hydrogenated to become 1,4-cyclohexanedicarboxylic acid dimethyl ester (DMCD), and in the second step, the DMCD ester is hydrogenated to generate CHDM.

[0004]

[0005] At present, the catalysts used for hydrogenation of DMT benzene ring to produce dimethyl 1,4-cyclohexanedicarboxylate are mainly supported catalysts with precious metals such as Pd, Pd, and Ru as active components. The traditional solution impregnation method is generally used. Affected by the solvation effect of the impregnation process and the clustering effect of the active components, the active components cannot be highly dispersed. In order to achieve catalytic activity that meets the needs of industrial production, it is necessary to increase the active content of precious metals, which cannot give full play to the role of the active catalytic sites of precious metals and will also increase production costs.

[0006] In addition, experiments have found that such catalysts in the prior art are prone to carbon monoxide poisoning, which can significantly affect the performance of palladium-based catalysts even at extremely low CO concentrations. Studies have shown that carbon monoxide poisoning of palladium-based catalysts occurs when the CO concentration in H2 exceeds 10 ppm. Currently, H2 used in industry generally contains hundreds or even thousands of ppm of carbon monoxide, which can have an adverse effect on catalytic activity.

[0007] CN1541762A reports a method for palladium catalyst to resist carbon monoxide poisoning, which is to add a ruthenium auxiliary agent, the ruthenium auxiliary agent is 3-6wt% in terms of ruthenium. CO produced in the hydrogenation reaction is absorbed or converted by the ruthenium auxiliary agent, reducing the possibility of palladium catalyst poisoning. However, ruthenium is also a precious metal. Although the addition of a large amount of ruthenium can alleviate the carbon monoxide poisoning phenomenon, the catalyst cost is also greatly increased, which is not suitable for industrial production.

[0008] Therefore, there is an urgent need to develop a catalyst with low content of precious metal active components, excellent catalytic activity, strong resistance to carbon monoxide poisoning, and which can be used to catalyze the hydrogenation of dimethyl terephthalate to produce dimethyl 1,4-cyclohexanedicarboxylate. Summary of the invention

[0009] The purpose of the present invention is to solve the problems of high content of noble metal active components, poor dispersibility, high production cost and weak resistance to carbon monoxide poisoning in the catalyst used for hydrogenating dimethyl terephthalate to produce dimethyl 1,4-cyclohexanedicarboxylate, and to provide a catalyst and a preparation method thereof as well as a preparation method of 1,4-cyclohexanedimethanol.

[0010] In order to achieve the above-mentioned purpose, the first aspect of the present invention provides a catalyst, wherein the catalyst comprises Pd, Co and a carrier; wherein, based on the total mass of the catalyst, the Pd content is 0.2-0.5wt%, the Co content is 0.12-0.3wt%, and the carrier content is 99.2-99.68wt%; the carrier is a mixed oxide of Al, Si and B, and the molar ratio of Al:Si:B is 3.4-4.2:1:0.2-0.3.

[0011] A second aspect of the present invention provides a method for preparing a catalyst, wherein the method comprises the following steps:

[0012] (P1) preparing an oxide gel mixture;

[0013] (P2) subjecting the oxide gel mixture to a ball rolling process to obtain a spherical precursor;

[0014] (P3) The spherical precursor is first impregnated in an impregnation solution containing a palladium source and a cobalt source, and then calcined to obtain the catalyst.

[0015] The third aspect of the present invention provides a method for preparing 1,4-cyclohexanedimethanol, wherein the method comprises:

[0016] T1, under the action of a first-stage catalyst, dimethyl terephthalate is contacted with hydrogen I to carry out a first-stage hydrogenation reaction to obtain an intermediate product; wherein the first-stage catalyst is the catalyst described in the first aspect of the present invention or the catalyst prepared according to the method described in the second aspect of the present invention;

[0017] T2, under the action of a second-stage catalyst, the intermediate product is contacted with hydrogen II to carry out a second-stage ester hydrogenation reaction to obtain 1,4-cyclohexanedimethanol.

[0018] Through the above technical solution, the beneficial technical effects achieved by the present invention are as follows:

[0019] 1) The catalyst provided in the present invention uses a composite oxide containing Al, Si and B as a carrier, and obtains a catalyst loaded with Pd and Co by an impregnation method, which can significantly improve the catalyst's ability to resist carbon monoxide poisoning. If a single oxide carrier is used, or a single Pd is used, or Co is replaced by other metal elements, the catalyst's ability to resist carbon monoxide poisoning cannot be significantly improved;

[0020] 2) When the catalyst provided in the present invention is used to catalyze the hydrogenation reaction of dimethyl terephthalate, the DMT conversion rate and DMCD selectivity can be ≥99%;

[0021] 3) The catalyst preparation method provided in the present invention, compared with first preparing alumina gel and borosilicate gel separately and then mixing the alumina gel and borosilicate gel, is to mix the aluminum source, silicon source and boron source in an alcohol solvent and perform an aging treatment together, that is, to prepare by a one-pot method. During the formation process, the alumina gel and borosilicate gel can produce certain entanglement or other affinity with each other, so that Al2O3, SiO2, and B2O3 are more evenly dispersed with each other, and can thus be better used as catalyst carriers;

[0022] 4) The method for preparing 1,4-cyclohexanedimethanol provided in the present invention has good stability and high product purity, and is suitable for industrial promotion. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is an electron microscope image of the catalyst prepared in Catalyst Preparation Example 1;

[0024] Figure 2 This is a partial magnified electron microscope image of the catalyst prepared in Catalyst Preparation Example 1. DETAILED DESCRIPTION

[0025] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0026] The first aspect of the present invention provides a catalyst, wherein the catalyst comprises Pd, Co and a carrier; wherein, based on the total mass of the catalyst, the Pd content is 0.2-0.5wt%, the Co content is 0.12-0.3wt%, and the carrier content is 99.2-99.68wt%; the carrier is a mixed oxide of Al, Si and B, and the molar ratio of Al:Si:B is 3.4-4.2:1:0.2-0.3.

[0027] Among them, the inventors have found through research that the mixed oxides of Al, Si and B, in synergy with Pd and Co elements, can significantly improve the catalyst's ability to resist carbon monoxide poisoning while reducing the content of Pd and Co elements. When the catalyst is used to catalyze the hydrogenation reaction of dimethyl terephthalate, the DMT conversion rate and DMCD selectivity can be ≥99%.

[0028] Wherein, in the present invention, the catalyst can be marked as Pd / Co@A x O y The catalyst, wherein A is Al, Si and B, x and y satisfy the oxide valence balance, the mixed oxide of the catalyst Al, Si and B is used as a carrier, and Pd and Co are loaded. In the Pd / Co@AxOy catalyst, the molar ratio of Al:Si:B is 3.4-4.2:1:0.2-0.3, the Pd content is 0.2-0.5wt%, and the Co content is 0.12-0.3wt%.

[0029] A second aspect of the present invention provides a method for preparing a catalyst, wherein the method comprises the following steps:

[0030] (P1) preparing an oxide gel mixture;

[0031] (P2) subjecting the oxide gel mixture to a ball rolling process to obtain a spherical precursor;

[0032] (P3) The spherical precursor is first impregnated in an impregnation solution containing a palladium source and a cobalt source, and then calcined to obtain the catalyst.

[0033] In step (1):

[0034] In one embodiment of the present invention, organic aluminum, tetraalkyl silicate and trialkyl borate are dispersed in an alcohol solvent, and then carbonate is added to obtain a dispersion; the dispersion is then subjected to an aging treatment to obtain an oxide gel mixture.

[0035] In one embodiment of the present invention, the organic aluminum is selected from at least one of aluminum isopropoxide and sec-butyl aluminum, the tetraalkyl silicate is selected from at least one of tetraethyl orthosilicate, tetrapropyl orthosilicate and tetrabutyl orthosilicate, and the trialkyl borate is selected from at least one of triisopropyl borate and tributyl borate.

[0036] In one embodiment of the present invention, the alcohol solvent is at least one of ethanol and isopropanol, and the carbonate is selected from at least one of sodium carbonate, potassium carbonate and ammonium carbonate. The amount of the carbonate is such that the pH value of the dispersion is 7.5-8.5. Preferably, after adding the carbonate, stirring is performed at room temperature for 4-6 hours. The room temperature has a well-known meaning and is not particularly limited in the present invention. For example, the room temperature may be 20-35°C.

[0037] In one embodiment of the present invention, the amounts of the organic aluminum, tetraalkyl silicate and trialkyl borate satisfy a molar ratio of Al:Si:B of 3.4-4.2:1:0.2-0.3.

[0038] In one embodiment of the present invention, in the dispersion, the content of the organic aluminum is 0.1-0.6 M, preferably 0.2-0.4 M, wherein M is mol / L.

[0039] In one embodiment of the present invention, the aging is performed by standing at 20-30° C. for 5-10 hours.

[0040] Among them, in the present invention, the inventors of the present invention have found through research that, compared with preparing alumina gel and borosilicate gel separately and then mixing the alumina gel and borosilicate gel, mixing the aluminum source, silicon source and boron source in an alcohol solvent and performing an aging treatment together, the alumina gel and borosilicate gel can produce a certain entanglement or other affinity with each other during the formation process, so that Al2O3, SiO2, and B2O3 are more evenly dispersed with each other, and can thus better serve as a catalyst carrier.

[0041] In one embodiment of the present invention, after the aging treatment is completed, solid-liquid separation and washing are performed to obtain an oxide gel mixture.

[0042] Wherein, in the present invention, the solid-liquid separation is preferably filtration or centrifugation, and the washing preferably includes alkaline water washing and clean water washing. For example, the washing is first washed with an alkaline aqueous solution with a pH of 10-12, and then washed with clean water until neutral, and the alkaline aqueous solution is NaOH and / or KOH solution.

[0043] In step (2):

[0044] In one embodiment of the present invention, the ball rolling treatment is carried out in a ball rolling machine, the speed of the ball rolling machine is 20-50 rpm, and the running time of the ball rolling machine is 5-10 hours. Among them, in the present invention, microspheres with a particle size of 1.5-4 mm can be obtained after the ball rolling treatment.

[0045] In step (3):

[0046] In one embodiment of the present invention, the palladium source is selected from at least one of palladium chloride and palladium chloride; the cobalt source is selected from at least one of cobalt chloride and cobalt nitrate.

[0047] In one embodiment of the present invention, the amounts of the palladium source, the cobalt source and the microsphere particles are such that the prepared catalyst has a Pd content of 0.2-0.5wt%, a Co content of 0.12-0.3wt% and a carrier content of 99.2-99.68wt%.

[0048] In one embodiment of the present invention, the solvent of the impregnation solution is at least one of water and alcohol solvents, preferably a mixed solvent of water and ethanol; wherein the volume concentration of ethanol in the mixed solvent of water and ethanol is 40-60%.

[0049] In one embodiment of the present invention, in the impregnation solution, based on the molar amount of Pd and Co elements, the content of the palladium source is 0.1-0.2M, and the content of the cobalt source is 0.03-0.05M.

[0050] In one embodiment of the present invention, the immersion is carried out under ultrasound; wherein the ultrasound frequency is 60-100 kHz, and the ultrasound time is 10-15 h.

[0051] In one embodiment of the present invention, solid-liquid separation and drying are performed after the impregnation. The solid-liquid separation is preferably centrifugation, and the drying can be oven drying or vacuum drying.

[0052] In one embodiment of the present invention, the calcination is carried out under a reducing atmosphere; preferably, the calcination is carried out under hydrogen.

[0053] In one embodiment of the present invention, the calcination operating conditions include: a calcination temperature of 400-600° C. and a calcination time of 3-5 h.

[0054] In the present invention, after calcination, the calcined product cooled to room temperature can be sieved, and the spherical particles with a particle size of 1.5-4 mm obtained by separation are the catalyst.

[0055] In one embodiment of the present invention, Pd / Co@A x O yThe specific preparation method of the catalyst can be: (P-1) preparing an AxOy oxide gel mixture, and obtaining a spherical precursor by a rolling ball machine; (P-2) under ultrasonic conditions, impregnating the spherical precursor in a solution containing a palladium source and a cobalt source. After the impregnation is completed, centrifugation, drying, calcining under a reducing atmosphere, cooling, and sieving to obtain a modified Pd / Co@Al2O3 / SiO2 / B2O3 catalyst.

[0056] The third aspect of the present invention provides a method for preparing 1,4-cyclohexanedimethanol, wherein the method comprises:

[0057] T1, under the action of a first-stage catalyst, dimethyl terephthalate is contacted with hydrogen I to carry out a first-stage hydrogenation reaction to obtain an intermediate product; wherein the first-stage catalyst is the catalyst described in the first aspect of the present invention or the catalyst prepared according to the method described in the second aspect of the present invention;

[0058] T2, under the action of a second-stage catalyst, the intermediate product is contacted with hydrogen II to carry out a second-stage ester hydrogenation reaction to obtain 1,4-cyclohexanedimethanol.

[0059] In step T1,

[0060] In one embodiment of the present invention, the dimethyl terephthalate and dimethyl 1,4-cyclohexanedicarboxylate are mixed and dissolved to obtain a mixed solution; the mixed solution is contacted with hydrogen I to perform a first-stage hydrogenation reaction to obtain a first-stage hydrogenation reaction product.

[0061] In one embodiment of the present invention, based on the total mass of the mixed solution, the mass concentration of dimethyl terephthalate is 10-50%, preferably 20-30%.

[0062] In one embodiment of the present invention, the CO concentration in the hydrogen I is lower than 1000 ppm, preferably lower than 500 ppm, and more preferably not more than 100 ppm.

[0063] In one embodiment of the present invention, the one-stage hydrogenation reaction is carried out in a one-stage hydrogenation reactor; wherein the one-stage hydrogenation reactor is a fixed bed reactor, the inlet temperature is 120-140°C, the temperature of the catalyst bed is 150-170°C, the hydrogen pressure is 4-8MPa, and the space velocity (LVSH) of dimethyl terephthalate is 0.4-1h -1 , the molar ratio of raw material hydrogen to oil is 30-150.

[0064] In one embodiment of the present invention, the mixed solution and hydrogen I are respectively heat exchanged with the first-stage hydrogenation reaction product, and the mixed solution and hydrogen I after heat exchange are mixed, and then preheated and enter from the top of the first-stage hydrogenation reactor, and the generated first-stage hydrogenation reaction product flows out from the lower part of the first-stage hydrogenation reactor.

[0065] In one embodiment of the present invention, the first stage hydrogenation reaction product after heat exchange enters a gas-liquid separation device, preferably enters a high-pressure gas-liquid separation tank, for a gas-liquid separation. The gas phase of the first stage gas-liquid separation is hydrogen, which is returned to the first stage hydrogenation reactor for recycling, and the liquid phase of the first stage gas-liquid separation is a crude DMCD product.

[0066] In one embodiment of the present invention, the crude DMCD product enters a first distillation separation unit for refining to obtain an intermediate product; wherein the intermediate product is dimethyl 1,4-cyclohexanedicarboxylate.

[0067] In one embodiment of the present invention, the intermediate product is divided into at least part A and part B, part A is returned to the first stage hydrogenation reaction and added to the mixed solution for recycling, and part B is contacted with hydrogen II for a second stage hydrogenation reaction.

[0068] In one embodiment of the present invention, the A portion accounts for 50-90% of the intermediate product, and the B portion accounts for 10-50% of the intermediate product.

[0069] In one embodiment of the present invention, the first-stage distillation separation unit includes a DMCD light component removal tower and a DMCD distillation tower; wherein the DMCD light component removal tower is used to remove impurities with a boiling point lower than the boiling point of dimethyl 1,4-cyclohexanedicarboxylate, and the bottom material of the DMCD light component removal tower is fed into the DMCD distillation tower; the DMCD distillation tower is used to separate the intermediate product.

[0070] In step T2,

[0071] In one embodiment of the present invention, the second-stage catalyst is a non-precious metal composite oxide catalyst. Wherein, the non-precious metal composite oxide catalyst is at least two of the oxides of copper, zinc and aluminum; preferably, the non-precious metal composite oxide catalyst is a composite metal oxide of copper oxide and zinc oxide, and optionally, also includes aluminum oxide. For example, the non-precious metal composite oxide catalyst contains: 30-40wt% of copper oxide, 50-60wt% of zinc oxide and 0-10wt% of aluminum oxide.

[0072] In one embodiment of the present invention, the intermediate product (or part B) is contacted with hydrogen II to carry out a two-stage ester hydrogenation reaction to obtain a two-stage ester hydrogenation reaction product; wherein the two-stage ester hydrogenation reaction is carried out in a two-stage hydrogenation reactor; wherein the catalyst bed temperature of the two-stage hydrogenation reactor is 190-220°C, the hydrogen pressure is 8-10MPa, and the space velocity (LVSH) of 1,4-cyclohexanedicarboxylic acid dimethyl ester is 0.2-0.4h -1 , the molar ratio of raw material hydrogen to oil is 80-150.

[0073] In one embodiment of the present invention, the intermediate product and hydrogen II are respectively heat exchanged with the second-stage ester hydrogenation reaction product, and the intermediate product and hydrogen II after heat exchange are mixed, and then preheated and enter from the top of the second-stage hydrogenation reactor, and the generated second-stage ester hydrogenation reaction product flows out from the lower part of the second-stage hydrogenation reactor.

[0074] In one embodiment of the present invention, the second-stage ester hydrogenation reaction product after heat exchange enters a second-stage gas-liquid separation device, preferably enters a second-stage high-pressure gas-liquid separation tank for second-stage gas-liquid separation. The gas phase of the second-stage gas-liquid separation is hydrogen and methanol. After low-temperature cooling and separation, most of the hydrogen that does not contain methanol is returned to the compressor for recycling, and the liquid phase of the second-stage gas-liquid separation is a crude CHDM product.

[0075] In one embodiment of the present invention, the CHDM crude product enters a two-stage distillation separation unit for refining to obtain 1,4-cyclohexanedimethanol.

[0076] In one embodiment of the present invention, the two-stage distillation separation unit includes a methanol removal tower, a CHDM light component removal tower, and a CHDM distillation tower; wherein the methanol removal tower is used to produce methanol at normal pressure, and the bottom material of the methanol removal tower is fed into the CHDM light component removal tower; the CHDM light component removal tower is used to remove impurities having a boiling point lower than the boiling point of 1,4-cyclohexanedimethanol, and the bottom material of the CHDM light component removal tower is fed into the CHDM distillation tower, and the CHDM distillation tower is used to separate 1,4-cyclohexanedimethanol.

[0077] In a preferred embodiment of the present invention, the method for preparing 1,4-cyclohexanedimethanol specifically comprises the following steps:

[0078] (S-1) dimethyl terephthalate and hydrogen are subjected to a one-stage hydrogenation reaction in the presence of a Pd / Co@AxOy catalyst to prepare dimethyl 1,4-cyclohexanedicarboxylate;

[0079] (S-2) 1,4-cyclohexanedimethanol is prepared by a two-stage hydrogenation reaction of dimethyl 1,4-cyclohexanedicarboxylate and hydrogen in the presence of a non-precious metal composite oxide catalyst;

[0080] In the Pd / Co@AxOy catalyst, A is Al, Si and B, x and y satisfy the oxide valence balance, and the mixed oxide of the catalyst Al, Si and B is used as a carrier to load Pd and Co.

[0081] Furthermore, in the Pd / Co@AxOy catalyst, the molar ratio of Al:Si:B is 3.4-4.2:1:0.2-0.3, the Pd content is 0.2-0.5wt%, and the Co content is 0.12-0.3wt%.

[0082] Further, in step (S1), the modified Pd / Co@AxOy catalyst is prepared by a preparation method comprising the following steps:

[0083] (P-1) preparing an AxOy oxide gel mixture and obtaining a spherical precursor using a rolling ball machine;

[0084] (P-2) Under ultrasonic conditions, the spherical precursor is impregnated in a solution containing a palladium source and a cobalt source. After the impregnation is completed, it is centrifuged, dried, calcined under a reducing atmosphere, cooled, and sieved to obtain a modified Pd / Co@Al2O3 / SiO2 / B2O3 catalyst.

[0085] Furthermore, in step (P-1), an organic aluminum, a tetraalkyl silicate, and a trialkyl borate are dispersed in an alcohol solvent, carbonate is added to adjust the pH to 7.5-8.5, stirred for 4-6 hours, aged, and washed to obtain an AxOy oxide gel mixture; preferably, the organic aluminum is selected from at least one of aluminum isopropoxide and sec-butyl aluminum, the tetraalkyl silicate is selected from at least one of tetraethyl orthosilicate, tetrapropyl orthosilicate, and tetrabutyl orthosilicate, and the trialkyl borate is selected from at least one of triisopropyl borate and tributyl borate; the organic aluminum, the tetraalkyl silicate, the borate The amount of trialkyl ester used satisfies the molar ratio of Al:Si:B of 3.4-4.2:1:0.2-0.3; the alcohol solvent is at least one of ethanol and isopropanol; the carbonate is selected from at least one of sodium carbonate, potassium carbonate and ammonium carbonate; the aging is standing at 20-30°C for 5-10 hours, the washing is first washed with an alkaline aqueous solution with a pH of 10-12, and then washed with clean water to neutrality, the alkaline aqueous solution is NaOH and / or KOH solution; the ball rolling machine speed is 20-50rpm, the ball rolling machine running time is 5-10 hours, and microspheres with a particle size of 1.5-4mm are obtained.

[0086] The inventor found that when preparing Al2O3 / SiO2 / B2O3 composite carrier materials, it is not possible to prepare alumina gel and borosilicate gel separately and then mix them. The present invention is to produce alumina gel and borosilicate gel at the same time through a one-pot method, and produce certain entanglement or other affinity with each other, so that Al2O3, SiO2, and B2O3 are more evenly dispersed with each other, and thus can be better used as catalyst carriers. The inventor unexpectedly found that the above-mentioned composite oxide containing Al, Si and B was used as a carrier, and a catalyst loaded with Pd and Co was obtained by an impregnation method, which had significantly improved resistance to carbon monoxide poisoning. If a single oxide carrier is used, or a single Pd is used, or Co is replaced by other metal elements, the resistance to carbon monoxide poisoning of the catalyst cannot be significantly improved. It is speculated that the composite oxide carrier and the Pd / Co bimetallic active center have a synergistic effect with each other, and the catalyst's resistance to carbon monoxide poisoning is improved under the joint action.

[0087] Furthermore, in step (P-2), the ultrasonic conditions are not particularly limited, such as impregnation at an ultrasonic frequency of 60-100kHz; the palladium source is selected from at least one of palladium chloride and palladium chloride; the cobalt source is selected from at least one of cobalt chloride and cobalt nitrate. In the solution of the palladium source and the cobalt source, the solvent is at least one of water and ethanol, preferably a mixed solvent of water and ethanol with an alcohol volume concentration of 40-60%; in the solution, the molar concentration of Pd is 0.1-0.2M, and the concentration of Co is 0.03-0.05M; the impregnation time is 10-15h. There is no special limitation on drying, and both drying and vacuum drying are possible. The reducing atmosphere is calcined under hydrogen, the calcination temperature is 400-600°C, and the calcination time is 3-5h. Sieving to obtain spherical particles with a particle size of 1.5-4mm.

[0088] Further, in step (S-2), the non-precious metal composite oxide type catalyst is at least two of the oxides of copper, zinc and aluminum; preferably, the non-precious metal composite oxide type catalyst is a composite metal oxide of copper oxide and zinc oxide, and optionally, also includes aluminum oxide. For example, in a specific embodiment of the present invention, in step (S2), copper oxide accounts for 30-40wt%, zinc oxide accounts for 50-60wt%, and the rest is aluminum oxide.

[0089] Furthermore, the preparation method of 1,4-cyclohexanedimethanol further specifically comprises the following steps:

[0090] (T-1) adding dimethyl terephthalate and dimethyl 1,4-cyclohexanedicarboxylate into a dissolving tank to obtain a mixed solution, the mixed solution enters a first-stage hydrogenation reaction unit, hydrogen is introduced for first-stage hydrogenation to obtain dimethyl 1,4-cyclohexanedicarboxylate, the crude product is separated into gas and liquid, the liquid phase enters a DMCD crude product tank, and then sent to a first-stage distillation separation unit for refining, a part of the refined dimethyl 1,4-cyclohexanedicarboxylate is recycled back to the dissolving tank as a solvent for the mixed solution, and the other part is sent to an intermediate product tank as a raw material for a second-stage hydrogenation reaction;

[0091] (T-2) The 1,4-cyclohexanedicarboxylic acid dimethyl ester in the intermediate product tank enters the second-stage hydrogenation reaction unit, hydrogen is introduced to carry out the second-stage ester hydrogenation reaction, the crude product is separated into gas and liquid, and the liquid phase enters the CHDM crude product tank and is then sent to the second-stage distillation separation unit for refining to obtain the product 1,4-cyclohexanedimethanol.

[0092] Furthermore, in step (T-1), the mass concentration of dimethyl terephthalate in the mixed solution is 10-50wt%, preferably 20-30wt%; the one-stage hydrogenation reaction unit is a fixed reaction bed, and the reaction conditions of the one-stage hydrogenation reaction unit are as follows: reactor inlet 120-140°C, catalyst bed temperature 150-170°C, hydrogen pressure 4-8MPa, dimethyl terephthalate space velocity (LVSH) 0.4-1.0h-1, and raw material hydrogen-to-oil molar ratio 30-150; CO concentration is lower than 1000ppm, preferably lower than 500ppm, and more preferably not more than 100ppm.

[0093] Furthermore, in step (T-1), a portion of the refined 1,4-cyclohexanedicarboxylic acid dimethyl ester, preferably 50-70wt%, is recycled back to the dissolution tank as a mixed solution solvent; the remaining portion is sent to an intermediate product tank as a second-stage hydrogenation reaction raw material.

[0094] Furthermore, in step (T-1), the mixed solution is heat exchanged with the reaction product from the first stage hydrogenation reaction unit, the hydrogen is heat exchanged with the reaction product of the first stage hydrogenation reaction unit through a circulating compressor, the mixed solution and hydrogen after heat exchange enter the first stage hydrogenation reactor from the top, and the product flows out from the lower part of the first stage hydrogenation reactor; the gas-liquid separation device is a high-pressure gas-liquid separation tank; after gas-liquid separation, the gas phase is hydrogen, which returns to the compressor for recycling; the first stage distillation separation unit includes a DMCD light component removal tower and a DMCD distillation tower. The pressure of the DMCD light component removal tower and the DMCD distillation tower is 1-3KPa; the tower top temperature is controlled at 120-150°C.

[0095] Further, in step (T-2), the catalyst bed temperature is 190-220°C, the hydrogen pressure is 8-10 MPa, the 1,4-cyclohexanedicarboxylic acid dimethyl ester space velocity (LVSH) is 0.2-0.4h-1, and the raw material hydrogen-to-oil molar ratio is 80-150; the 1,4-cyclohexanedicarboxylic acid dimethyl ester is heat exchanged with the product of the second-stage hydrogenation reaction unit, the hydrogen is heat exchanged with the reaction product of the second-stage hydrogenation reaction unit through a circulating compressor, the heat exchanged 1,4-cyclohexanedicarboxylic acid dimethyl ester and hydrogen are mixed, preheated, and then heated from the second stage hydrogenation reaction unit. The first stage hydrogenation reactor is added at the top, and the product flows out from the bottom; the gas-liquid separation device is a high-pressure gas-liquid separation tank; after gas-liquid separation, the gas phase is hydrogen and methanol. After low-temperature cooling and separation, most of the hydrogen without methanol is returned to the compressor for recycling; the second stage distillation separation unit includes a methanol removal tower, a CHDM light component removal tower, and a CHDM distillation tower; methanol is extracted from the methanol removal tower under normal pressure, the tower bottom liquid is sent to the CHDM light component removal tower, the tower bottom material is sent to the CHDM distillation tower, and the product 1,4-cyclohexanedimethanol is extracted from the tower top. The pressure of the CHDM light component removal tower and the CHDM distillation tower is 1-3kPa, and the tower top temperature is controlled at 150-170℃.

[0096] The present invention will be described in detail below through examples.

[0097] Catalyst Preparation Example 1

[0098] (P1) Aluminum isopropoxide, tetraethyl orthosilicate, and triisopropyl borate are added into a reaction kettle at a molar ratio of Al:Si:B=3.4:1:0.2, and ethanol is added to fully disperse them to obtain a dispersion, wherein the molar concentration of aluminum isopropoxide in the dispersion is 0.2M, and ammonium carbonate is added to adjust the pH to 8.5, and the dispersion is stirred for 5 hours, then aged at 25°C for 8 hours, centrifuged, washed with a NaOH aqueous solution with a pH of 12, and then washed with clean water until the effluent is neutral, to obtain a mixed oxygen compound gel;

[0099] (P2) through a ball rolling machine, adjusting the speed to 50 rpm, and running the ball rolling machine for 6 hours to obtain a spherical precursor with an average particle size of 1.9 mm;

[0100] (P3) Under 100kHz ultrasonic conditions, the spherical precursor obtained in step (P1) was immersed in an ethanol aqueous solution containing 0.2M H2PdCl4 and 0.05M CoCl2 (ethanol volume concentration 60%) for 10 hours. The mixture was centrifuged, dried, calcined at 500°C for 5 hours in a H2 atmosphere, cooled, and sieved to obtain spherical particles with an average particle size of 1.9 mm.

[0101] After testing, the Pd content in the catalyst is 0.42wt%, the Co content is 0.19wt%, the content of the carrier is 99.39wt%, and the molar ratio of Al, Si and B elements in the carrier is 3.4:1:0.2.

[0102] Figure 1 is an electron microscope photograph of the catalyst obtained in Preparation Example 1, Figure 2 This is a partial enlarged view of the electron microscope photograph of the catalyst obtained in Preparation Example 1.

[0103] Preparation Example 2

[0104] The other conditions are the same as those in Preparation Example 1, except that in step (P1), aluminum isopropoxide, tetraethyl orthosilicate, and triisopropyl borate are added to the reactor at a molar ratio of Al:Si:B=4.2:1:0.3. After testing, the Pd content of the spherical particle catalyst obtained in this preparation example is 0.41wt%, the Co content is 0.19wt%, the content of the carrier is 99.40wt%, and the molar ratio of Al, Si and B elements in the carrier is 4.2:1:0.3.

[0105] Preparation Example 3

[0106] The other conditions are the same as those in Preparation Example 1, except that in step (P2), the concentration of H2PdCl4 is 0.1 M, and the concentration of CoCl2 is 0.03 M. After testing, the Pd content in the spherical particle catalyst obtained in this preparation example is 0.21wt%, the Co content is 0.12wt%, the content of the carrier is 99.67wt%, and the molar ratio of Al, Si and B elements in the carrier is 3.4:0.2:1.

[0107] Comparative Preparation Example 1

[0108] The other conditions are the same as those in Preparation Example 1, except that in step (P1), tetraethyl orthosilicate is not added.

[0109] Comparative Preparation Example 2

[0110] Other conditions were the same as those in Preparation Example 1, except that in step (P1), triisopropyl borate was not added.

[0111] Comparative Preparation Example 3

[0112] The other conditions were the same as those in Preparation Example 1, except that in step (P3), 0.02 M CoCl2 was replaced by 0.02 M RuCl3.

[0113] Comparative Preparation Example 4

[0114] The other conditions were the same as those in Preparation Example 1, except that in step (P3), 0.02 M CoCl2 was replaced by 0.02 M ZnCl2.

[0115] Comparative Preparation Example 5

[0116] The other conditions were the same as those in Preparation Example 1, except that in step (P3), 0.02 M CoCl2 was replaced by 0.02 M NiCl2.

[0117] Example 1

[0118] (T1) dimethyl terephthalate (DMT) is added to a dissolving tank, and dimethyl 1,4-cyclohexanedicarboxylate (DMCD) is added to the dissolving tank through a first-stage distillation separation unit via a flow controller to obtain a mixed solution, wherein the mass concentration of DMT in the mixed solution is 25%;

[0119] The mixed solution is heat exchanged with the first-stage hydrogenation reaction product flowing out of the lower part of the first-stage hydrogenation reactor, and hydrogen I (carbon monoxide content <5ppm) is heat exchanged with the first-stage hydrogenation reaction product flowing out of the lower part of the first-stage hydrogenation reactor through a compressor. The two heat-exchanged materials are mixed, preheated, and then pressurized by a feed pump to enter the first-stage hydrogenation reactor from the top to perform a first-stage hydrogenation reaction to obtain a first-stage hydrogenation reaction product; wherein the first-stage hydrogenation reactor is a fixed bed reactor, the inlet temperature is 130°C, the first-stage catalyst in the catalyst bed is obtained in Preparation Example 1, the catalyst bed temperature is 160°C, the H2 pressure is 5MPa, and the dimethyl terephthalate space velocity (LVSH) is 0.5h -1 , the raw material hydrogen oil molar ratio is 100;

[0120] The first stage hydrogenation reaction product flows out from the lower part of the first stage hydrogenation reactor, exchanges heat with the mixed solution and hydrogen I for cooling, and then enters the first stage high-pressure gas-liquid separation tank for gas-liquid separation. The gas phase of the first stage gas-liquid separation is mainly hydrogen, which returns to the first stage hydrogenation reactor for recycling. The liquid phase of the first stage gas-liquid separation is the crude DMCD product.

[0121] The crude DMCD product is sent to a crude product tank and then to a first-stage distillation separation unit for refining, wherein the crude DMCD product is first sent to a DMCD light component removal tower (tower top pressure 3 kPa, tower top temperature 120°C) to remove impurities with a boiling point lower than that of dimethyl 1,4-cyclohexanedicarboxylate, and the bottom material of the DMCD light component removal tower is sent to a DMCD distillation tower (tower top pressure 3 kPa, tower top temperature 150°C), and the intermediate product (DMCD purity> 99.9%) is extracted from the top of the DMCD distillation tower;

[0122] The intermediate product is divided into part A and part B, with part A accounting for 75% of the intermediate product mass and part B accounting for 25% of the intermediate product mass. Part A is recycled back to the dissolution tank as a mixed solution solvent, and part B is sent to the intermediate product tank as a secondary hydrogenation reaction raw material; DMT conversion rate is 99.9%, and DMCD selectivity is 99.5%;

[0123] (T2) DMCD in the intermediate product tank is heat exchanged with the second-stage ester hydrogenation reaction product flowing out of the lower part of the second-stage hydrogenation reactor, hydrogen II is heat exchanged with the second-stage ester hydrogenation reaction product flowing out of the lower part of the second-stage hydrogenation reactor through a compressor, and the two materials after heat exchange are mixed and preheated and then enter the second-stage hydrogenation reactor from the top to carry out the second-stage ester hydrogenation reaction to obtain the second-stage ester hydrogenation reaction product; wherein, the inlet temperature of the second-stage hydrogenation reactor is 150°C, the second-stage catalyst in the catalyst bed is a composite metal oxide, wherein copper oxide 34wt%, zinc oxide 57wt%, aluminum oxide 9wt%; the catalyst bed temperature is 210°C, the H2 pressure is 8MPa, and the space velocity (LVSH) of 1,4-cyclohexanedicarboxylic acid dimethyl ester is 0.3h -1 , the raw material hydrogen-to-oil molar ratio is 80;

[0124] The second-stage ester hydrogenation reaction product flows out from the lower part of the second-stage hydrogenation reactor, exchanges heat with DMCD and hydrogen II entering the second-stage hydrogenation reactor for cooling, and then enters the second-stage high-pressure gas-liquid separation tank for second-stage gas-liquid separation. The gas phase of the second-stage gas-liquid separation is mainly hydrogen and methanol. After low-temperature cooling and separation, the hydrogen without methanol returns to the second-stage hydrogenation reactor for recycling. The liquid phase of the second-stage gas-liquid separation is the CHDM crude product.

[0125] The CHDM crude product is sent to a CHDM crude product tank and then to a two-stage distillation separation unit for refining, wherein the CHDM crude product is sent to a methanol removal tower, methanol is extracted from the top of the tower under normal pressure, the bottom material of the methanol removal tower is sent to a CHDM light component removal tower (tower top pressure 3 kPa, tower top temperature 150°C), impurities with a boiling point lower than that of 1,4-cyclohexanedimethanol are removed, the bottom material of the CHDM light component removal tower is sent to a CHDM distillation tower (tower top pressure 3 kPa, tower top temperature 170°C), and CHDM product is extracted from the top of the tower after distillation; the DMCD conversion rate is 99.4%, and the CHDM selectivity is 98.5%.

[0126] Examples 2-3, and Comparative Examples 1-5

[0127] Other conditions and operations are the same as those in Example 1, except that in step (T1), the catalyst bed of the first-stage hydrogenation reactor uses the first-stage catalysts prepared in Preparation Examples 2-3 and Comparative Preparation Examples 1-5. The properties of the first-stage catalysts are shown in Table 1:

[0128] Among them, the anti-carbon monoxide poisoning is to judge whether the DMT conversion rate can be maintained at 99% and the DMCD selectivity can be maintained at 97% under the condition of 100ppm of carbon monoxide in hydrogen for one month. If it can be maintained, it is qualified. If any of the DMT conversion rate and DMCD selectivity cannot meet the requirements, it is unqualified.

[0129] Table 1

[0130]

[0131]

[0132] From the data in Table 1, it can be seen that the present invention uses an oxide mixture containing Al, Si, and B as a carrier, loads Pd and Co bimetallics, and hydrogenates dimethyl terephthalate (DMT) to prepare dimethyl 1,4-cyclohexanedicarboxylate (DMCD). The DMT conversion rate and DMCD selectivity are excellent and can meet the requirements of industrialization. Importantly, the catalyst prepared in the preparation example of the present invention shows unexpectedly good resistance to carbon monoxide poisoning.

[0133] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A catalyst, characterized in that The catalyst comprises Pd, Co and a carrier; wherein, based on the total mass of the catalyst, the Pd content is 0.2-0.5wt%, the Co content is 0.12-0.3wt%, and the carrier content is 99.2-99.68wt%; the carrier is a mixed oxide of Al, Si and B, and the molar ratio of Al:Si:B is 3.4-4.2:1:0.2-0.

3.

2. A method for preparing a catalyst, characterized in that: The method comprises the following steps: (P1) preparing an oxide gel mixture; (P2) subjecting the oxide gel mixture to a ball rolling process to obtain a spherical precursor; (P3) The spherical precursor is first impregnated in an impregnation solution containing a palladium source and a cobalt source, and then calcined to obtain the catalyst.

3. The preparation method according to claim 2, wherein Organic aluminum, tetraalkyl silicate and trialkyl borate are dispersed in an alcohol solvent, and then carbonate is added to obtain a dispersion; then the dispersion is subjected to an aging treatment to obtain an oxide gel mixture.

4. The preparation method according to claim 3, wherein The organic aluminum is selected from at least one of aluminum isopropoxide and sec-butyl aluminum, the tetraalkyl silicate is selected from at least one of tetraethyl orthosilicate, tetrapropyl orthosilicate and tetrabutyl orthosilicate, and the trialkyl borate is selected from at least one of triisopropyl borate and tributyl borate; And / or, the alcohol solvent is at least one of ethanol and isopropanol, and the carbonate is at least one of sodium carbonate, potassium carbonate and ammonium carbonate; And / or, the amounts of the organic aluminum, tetraalkyl silicate and trialkyl borate satisfy the molar ratio of Al:Si:B of 3.4-4.2:1:0.2-0.3; and / or, the carbonate is used in an amount such that the pH value of the dispersion is 7.5-8.5, and the carbonate is added and stirred for 4-6 hours; And / or, the aging is standing at 20-30° C. for 5-10 hours; And / or, washing is performed after the aging treatment is completed, first with an alkaline aqueous solution with a pH of 10-12, and then with clean water until neutral, the alkaline aqueous solution being a NaOH and / or KOH solution; And / or, the ball rolling treatment is carried out in a ball rolling machine, wherein the speed of the ball rolling machine is 20-50 rpm, the running time of the ball rolling machine is 5-10 hours, and microspheres with a particle size of 1.5-4 mm are obtained.

5. The preparation method according to claim 2, wherein: The palladium source is selected from at least one of palladium chloride and palladium chloride; the cobalt source is selected from at least one of cobalt chloride and cobalt nitrate; And / or, the amount of the palladium source, the cobalt source and the microsphere particles is such that the prepared catalyst has a Pd content of 0.2-0.5wt%, a Co content of 0.12-0.3wt%, and a carrier content of 99.2-99.68wt%; And / or, the solvent of the impregnation solution is at least one of water and alcohol solvents, preferably a mixed solvent of water and ethanol; wherein the volume concentration of ethanol in the mixed solvent of water and ethanol is 40-60%; And / or, in the impregnation solution, the content of the palladium source is 0.1-0.2M, and the content of the cobalt source is 0.03-0.05M, based on the molar amount of Pd and Co elements; And / or, the immersion is carried out under ultrasound; wherein the ultrasound frequency is 60-100 kHz and the ultrasound time is 10-15 h; And / or, the calcination is carried out under a reducing atmosphere; preferably, the calcination is carried out under hydrogen; And / or, the calcination operating conditions include: calcination temperature of 400-600°C, calcination time of 3-5h; And / or, the calcination is followed by cooling and sieving to obtain spherical particles with a particle size of 1.5-4 mm.

6. A method for preparing 1,4-cyclohexanedimethanol, characterized in that: The method The following steps are involved: T1, under the action of a first-stage catalyst, dimethyl terephthalate is contacted with hydrogen I to carry out a first-stage hydrogenation reaction to obtain an intermediate product; wherein the first-stage catalyst is the catalyst according to claim 1 or a catalyst prepared by the method according to any one of claims 2 to 5; T2, under the action of a second-stage catalyst, the intermediate product is contacted with hydrogen II to carry out a second-stage ester hydrogenation reaction to obtain 1,4-cyclohexanedimethanol.

7. The preparation method according to claim 6, wherein: Mixing and dissolving the dimethyl terephthalate and dimethyl 1,4-cyclohexanedicarboxylate to obtain a mixed solution; contacting the mixed solution with hydrogen I to perform a first-stage hydrogenation reaction to obtain a first-stage hydrogenation reaction product; and / or, based on the total mass of the mixed solution, the mass concentration of dimethyl terephthalate is 10-50%; and / or, the CO concentration in the hydrogen I is lower than 1000 ppm; And / or, the one-stage hydrogenation reaction is carried out in a one-stage hydrogenation reactor; wherein the one-stage hydrogenation reactor is a fixed bed reactor, the inlet temperature is 120-140°C, the temperature of the catalyst bed is 150-170°C, the hydrogen pressure is 4-8MPa, and the space velocity (LVSH) of dimethyl terephthalate is 0.4-1h -1 , the raw material hydrogen-to-oil molar ratio is 30-150; And / or, the mixed solution and hydrogen I are respectively heat exchanged with the first-stage hydrogenation reaction product, the mixed solution and hydrogen I after heat exchange are mixed, and then preheated and enter from the top of the first-stage hydrogenation reactor, and the generated first-stage hydrogenation reaction product flows out from the lower part of the first-stage hydrogenation reactor; And / or, the first stage hydrogenation reaction product after heat exchange enters a first stage gas-liquid separation device for first stage gas-liquid separation, wherein the first stage gas-liquid separation gas phase is hydrogen, which is returned to the first stage hydrogenation reactor for recycling, and the first stage gas-liquid separation liquid phase is a DMCD crude product; And / or, the crude DMCD product enters a distillation separation unit for a stage of refining to obtain an intermediate product; wherein the intermediate product is dimethyl 1,4-cyclohexanedicarboxylate; And / or, the intermediate product is divided into at least part A and part B, the part A is returned to the first stage hydrogenation reaction and added to the mixed solution for recycling, and the part B is contacted with hydrogen II for a second stage hydrogenation reaction; And / or, the A part accounts for 50-90% of the intermediate product, and the B part accounts for 10-50% of the intermediate product.

8. The preparation method according to claim 7, wherein: The first stage distillation separation unit includes a DMCD light component removal tower and a DMCD distillation tower; wherein the DMCD light component removal tower is used to remove impurities with a boiling point lower than that of dimethyl 1,4-cyclohexanedicarboxylate, and the bottom material of the DMCD light component removal tower is fed into the DMCD distillation tower; the DMCD distillation tower is used to separate the intermediate product.

9. The preparation method according to claim 6, wherein: The second stage catalyst is a non-precious metal composite oxide type catalyst; wherein the non-precious metal composite oxide type catalyst is at least two of the oxides of copper, zinc and aluminum; and / or, contacting the intermediate product with hydrogen II to carry out a two-stage ester hydrogenation reaction to obtain a two-stage ester hydrogenation reaction product; wherein the two-stage ester hydrogenation reaction is carried out in a two-stage hydrogenation reactor; the catalyst bed temperature of the two-stage hydrogenation reactor is 190-220° C., the hydrogen pressure is 8-10 MPa, and the space velocity (LVSH) of 1,4-cyclohexanedicarboxylic acid dimethyl ester is 0.2-0.4 h -1 , the raw material hydrogen-to-oil molar ratio is 80-150; And / or, the intermediate product and hydrogen II are respectively heat exchanged with the second-stage ester hydrogenation reaction product, the intermediate product and hydrogen II after heat exchange are mixed, and then preheated and enter from the top of the second-stage hydrogenation reactor, and the generated second-stage ester hydrogenation reaction product flows out from the lower part of the second-stage hydrogenation reactor; And / or, the second-stage ester hydrogenation reaction product after heat exchange enters the second-stage gas-liquid separation device for second-stage gas-liquid separation, the gas phase of the second-stage gas-liquid separation is hydrogen and methanol, after low-temperature cooling and separation, the hydrogen part without methanol is returned to the compressor for recycling, and the liquid phase of the second-stage gas-liquid separation is the CHDM crude product; And / or, the CHDM crude product enters a two-stage distillation separation unit for refining to obtain 1,4-cyclohexanedimethanol.

10. The preparation method according to claim 9, wherein: The two-stage distillation separation unit includes a methanol removal tower, a CHDM light component removal tower and a CHDM distillation tower; The methanol removal tower is used to produce methanol under normal pressure, and the bottom materials of the methanol removal tower are sent to the CHDM light component removal tower; The CHDM light component removal tower is used to remove impurities with a boiling point lower than that of 1,4-cyclohexanedimethanol, and the bottom materials of the CHDM light component removal tower are fed into the CHDM distillation tower; The CHDM distillation tower is used to separate 1,4-cyclohexanedimethanol.

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