Hydrogenation catalyst, preparation method thereof and application of hydrogenation catalyst in hydrogenation of 2, 2, 4, 4-tetramethyl-1, 3-cyclobutanedione

Abstract

The invention discloses a hydrogenation catalyst and a preparation method and application thereof in hydrogenation of 2, 2, 4, 4-tetramethyl-1, 3-cyclobutanedione, the catalyst is a nitrogen-doped carbon nanotube loaded metal cobalt / bismuth catalyst, the preparation method comprises the following steps: 1) taking cotton straw, grinding into powder, adding an acid solution, a cobalt salt and a bismuth salt, stirring, then carrying out a hydration reaction, and filtering to obtain a filtrate; filtering to obtain cobalt / bismuth doped straw powder; and 2) roasting the cobalt / bismuth-doped straw powder in a nitrogen atmosphere to obtain the nitrogen-doped carbon nanotube loaded metal cobalt / bismuth catalyst. According to the preparation method, by preparing the novel hydrogenation catalyst, the selectivity of CBDO is improved, the proportion of cis-trans isomers is increased, meanwhile, it is ensured that the catalyst can stably operate for a long period, and the production cost of a device is greatly reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of catalyst preparation, and specifically relates to a hydrogenation catalyst and a preparation method thereof, and application of the catalyst in preparing 2,2,4,4-tetramethyl-1,3-cyclobutanediol by hydrogenating 2,2,4,4-tetramethyl-1,3-cyclobutanedione. Background Art

[0002] 2,2,4,4-Tetramethyl-1,3-cyclobutanediol (CBDO) is an important chemical raw material with important application value in the synthesis of high-performance polyesters, food contact materials, biodegradable polyesters, etc. As an aliphatic diol, CBDO produces high-performance polyesters with excellent thermal stability. It is often used as a heat-resistant modification component to significantly improve the glass transition temperature, weather resistance and transparency of polyesters.

[0003] At present, the preparation of CBDO mainly includes the isobutyric anhydride method and the isobutyryl chloride method. Patents US8420868B2, US8420869B2, and CN201910399132.9 disclose methods for synthesizing CBDO using isobutyric anhydride. First, isobutyric anhydride is pyrolyzed to generate dimethyl ketone (DMK), followed by dimethyl ketone dimerization to form 2,2,4,4-tetramethylcyclobutanedione (CBDK), and then the diketone is catalytically hydrogenated to form a CBDO product. Patent CN202110100278.6 discloses a method for synthesizing CBDO from isobutyryl chloride. Currently, the isobutyric anhydride method is the mainstream process for industrial CBDO production. Among them, CBDK hydrogenation is the key to this process.

[0004] In the prior art of preparing CBDO by hydrogenation of CBDK, patents US2936324A and US3190928A disclose ruthenium-based and nickel-based catalysts, with a reaction pressure of 5-20MPa and a product yield of 90%-95%. The reaction pressure is high and the yield is low. Patent CN202010755097.2 discloses a method for preparing 2,2,4,4-tetramethyl-1,3-cyclobutanediol with a high cis-trans ratio, using a catalyst whose main active metal is one or more of Ru, Ni, Pd and Pt, and the hydrogenation selectivity is more than 99%, but it requires two steps of hydrogenation and isomerization, and the reaction process is more complicated. And the patent does not mention the life of the catalyst.

[0005] CBDK hydrogenation is the key to the CBDO production process. How to improve the selectivity of CBDO, improve cis-trans isomerization and ensure the long-term stable operation of the catalyst is the difficulty of CBDK hydrogenation technology. Therefore, it is necessary to develop a new catalyst to solve the problems existing in the existing technology. Summary of the invention

[0006] In view of the above problems existing in the prior art, one of the objects of the present invention is to provide a hydrogenation catalyst and a preparation method thereof. The catalyst is a nitrogen-doped carbon nanotube-loaded metal cobalt / bismuth catalyst, which uses bio-based material cotton straw as raw material, is inexpensive and a renewable resource. The catalyst preparation method is simple and easy to obtain, and large-scale production is easy to achieve, and the catalyst can be recycled and reused.

[0007] The second object of the present invention is to provide a method for catalyzing the hydrogenation of CBDK to generate CBDO. The above-mentioned hydrogenation catalyst can solve the problems of low selectivity and complex process flow in the prior art, improve the economic efficiency of the device, and ensure that the catalyst can be stably applied for more than 100 times. In order to achieve the above invention objects, the technical scheme of the present invention is as follows:

[0008] One aspect of the present invention provides a hydrogenation catalyst, which is a nitrogen-doped carbon nanotube-supported metal cobalt / bismuth catalyst.

[0009] Another aspect of the present invention also provides a method for preparing the nitrogen-doped carbon nanotube-supported metal cobalt / bismuth catalyst, the steps comprising:

[0010] 1) Grinding cotton straw into powder, adding acid solution, cobalt salt and bismuth salt and stirring, then performing hydration reaction, and filtering to obtain cobalt / bismuth doped straw powder;

[0011] 2) The cobalt / bismuth doped straw powder is calcined in a nitrogen atmosphere to obtain the nitrogen-doped carbon nanotube-loaded metal cobalt / bismuth catalyst.

[0012] In the present invention, the cotton straw in step 1) is long-staple cotton straw, fine-staple cotton straw, or Egyptian cotton straw, preferably long-staple cotton straw;

[0013] Preferably, the cotton straw is ground into a powder with a particle size of 1.5-20 microns.

[0014] In the present invention, the acid solution in step 1) is an aqueous solution of an acid, and the concentration is preferably 1-10wt%, such as 1wt%, 3wt%, 5wt%, 8wt%, 10wt%, etc.;

[0015] Preferably, the acid is selected from inorganic acids, preferably one or more of hydrochloric acid and sulfuric acid.

[0016] In the present invention, the cobalt salt in step 1) is selected from one or more of cobalt nitrate, cobalt phosphate and cobalt chloride.

[0017] In the present invention, the bismuth salt in step 1) is selected from one or more of bismuth nitrate, bismuth phosphate and bismuth acetate.

[0018] In the present invention, the mass ratio of the cotton straw to the acid solution, the cobalt salt and the bismuth salt in step 1) is 1:(3-5):(0.2-0.5):(0.03-0.08), which can be 1:(for example, 3, 3.5, 4, 4.5, 5, etc.):(for example, 0.2, 0.3, 0.4, 0.5, etc.):(for example, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, etc.).

[0019] In the present invention, the stirring in step 1) is performed at a temperature of 20-50°C, such as 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, etc., and the time is 4-8h, such as 4h, 5h, 6h, 7h, 8h, etc.

[0020] In the present invention, the hydration reaction in step 2) is carried out at a temperature of 100-150°C, such as 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, etc., and for a time of 3-6h, such as 3h, 4h, 5h, 6h, etc.

[0021] In the present invention, step 2) adopts a tubular furnace for calcining at a temperature of 600-800°C, such as 600°C, 650°C, 700°C, 750°C, 800°C, etc., and a time of 4-12h, such as 4h, 6h, 8h, 10h, 12h, etc.

[0022] The above-mentioned hydrogenation catalyst preparation method provided by the present invention uses bio-based material cotton stalks as raw materials, and a porous carbon matrix can be obtained by roasting. Cobalt can easily catalyze the production of carbon nanotubes on the surface of the porous carbon matrix at 600-800°C, so that the carbon matrix grows from a two-dimensional structure to a three-dimensional structure, increasing the specific surface area of ​​the catalyst while increasing the number of active sites, thereby greatly improving the activity of the catalyst.

[0023] In yet another aspect, the present invention provides use of the above hydrogenation catalyst.

[0024] A method for preparing 2,2,4,4-tetramethyl-1,3-cyclobutanediol (CBDO) by hydrogenating 2,2,4,4-tetramethyl-1,3-cyclobutanedione (CBDK), wherein the method uses 2,2,4,4-tetramethyl-1,3-cyclobutanedione (CBDK) and hydrogen as raw materials, and performs a hydrogenation reaction catalyzed by a hydrogenation catalyst in a solvent environment to prepare the 2,2,4,4-tetramethyl-1,3-cyclobutanediol;

[0025] The hydrogenation catalyst is the nitrogen-doped carbon nanotube-supported metal cobalt / bismuth catalyst.

[0026] In the present invention, the solvent is selected from one or more of cyclohexane, isobutyl isobutyrate, and methyl isobutyl ketone, preferably isobutyl isobutyrate.

[0027] In the present invention, the concentration of 2,2,4,4-tetramethyl-1,3-cyclobutanedione in the solvent is 1-8wt%, for example, 1wt%, 3wt%, 5wt%, 7wt%, 8wt% and the like.

[0028] In the present invention, the amount of the hydrogenation catalyst is 0.05-5wt% based on the total mass of CBDK and the solvent, for example, 0.05wt%, 1wt%, 2wt%, 3wt%, 4wt%, 5wt%, etc.

[0029] In the present invention, the hydrogenation reaction has a reaction temperature of 100-180°C, such as 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, etc., preferably 120-150°C, and a reaction pressure of 1-5MPa, such as 1MPa, 2MPa, 3MPa, 4MPa, 5MPa, etc., preferably 1-3MPa;

[0030] Preferably, the hydrogenation reaction has a reaction time of 1-8 h, such as 1 h, 3 h, 5 h, 7 h, 8 h, etc., preferably 2-4 h.

[0031] In the present invention, the reactor for the hydrogenation reaction is a reactor, and the reactor is preferably an intermittent reactor; after the hydrogenation reaction is completed, the catalyst can be separated from the reaction liquid by conventional methods such as filtration, and the recovered catalyst can be directly recycled and reused for more than 100 times.

[0032] In the present invention, the conversion rate of the hydrogenation reaction can reach more than 99%, the selectivity can reach more than 99%, and the CBDO cis-trans ratio can be controlled to be more than 30, preferably more than 50.

[0033] In the method for preparing CBDO by catalytic hydrogenation of CBDK provided by the present invention, the above-mentioned nitrogen-doped carbon nanotube-supported metal cobalt / bismuth catalyst is used, and the three-dimensional structure of the carbon matrix allows the structure on one side of CBDK to be adsorbed on the catalyst surface, and reacts with the active hydrogen adsorbed on the cobalt, which is beneficial to the conversion of CBDK into cis-CBDO and improves the cis-trans ratio of CBDO. By adding bismuth, the solvent isobutyl isobutyrate can be effectively prevented from decomposing into isobutyric acid during the reaction, which can corrode the catalyst and greatly improve the life of the catalyst.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] (1) The raw material of hydrogenation catalyst is bio-based material cotton straw, which is cheap and a renewable resource. The catalyst preparation method is simple and easy to obtain, and it is relatively easy to mass produce;

[0036] (2) The hydrogenation catalyst is a three-dimensional carbon nanotube structure, and the active catalyst cobalt grows on the surface of the carbon nanotube, which improves the hydrogenation activity and selectivity of the catalyst;

[0037] (3) The addition of bismuth to the hydrogenation catalyst increases the service life of the catalyst. The catalyst can be used more than 100 times, which greatly reduces the cost of the catalyst and improves the economic efficiency of the device. DETAILED DESCRIPTION

[0038] In order to facilitate the understanding of the present invention, the present invention will be further described below in conjunction with examples. It should be understood that the following examples are only for a better understanding of the present invention and do not mean that the present invention is limited to the following examples.

[0039] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the invention belongs. The term "and / or" as may be used herein includes any and all combinations of one or more of the associated listed items.

[0040] In the embodiments and comparative examples of the present invention, the sources of the main raw materials used are shown in Table 1 below. Unless otherwise specified, other raw materials and reagents were purchased from common commercial sources:

[0041] Table 1 Main raw material sources

[0042] Raw material name Specification factory Isobutyl isobutyrate AR Xilong Chemical Industry Co., Ltd. CBDK ＞99％ self made Hydrochloric acid aqueous solution 37％ Xilong Chemical Industry Co., Ltd. Cobalt Acetate AR Sinopharm Chemical Reagent Co., Ltd. Bismuth acetate AR Sinopharm Chemical Reagent Co., Ltd.

[0043] The main analysis methods used in the examples and comparative examples of the present invention are as follows:

[0044] Analytical instrument: Agilent 7820, capillary column (wax);

[0045] Gas phase analysis method: area normalization method;

[0046] Gas phase analysis conditions: vaporization chamber temperature was 270°C, detector temperature was 270°C, column temperature was programmed: 50°C, 5 min; 80°C, 10°C / min to 250°C, 5 min.

[0047] Example 1

[0048] Preparation of nitrogen-doped carbon nanotube-supported metal cobalt / bismuth catalysts (numbered as catalysts 1-3)

[0049] Catalyst 1: Grind long-staple cotton stalks into powder with a particle size of 5 microns, add them into a beaker, and then add 5wt% HCl aqueous solution, cobalt nitrate, and bismuth acetate, and the mass ratio of long-staple cotton stalk powder: 5wt% HCl aqueous solution: cobalt nitrate: bismuth acetate is 1:3:0.3:0.08. After mixing, stir at 20°C for 8h; then place in a hydration kettle, hydrate at 100°C for 6h, filter to obtain cobalt / bismuth-doped straw powder; place the powder in a tubular furnace, and roast at 600°C in a nitrogen atmosphere for 12h to obtain catalyst 1.

[0050] Catalyst 2: Grind fine cotton straw into powder with a particle size of 1.5 microns, add it into a beaker, and then add 10wt% H2SO4 aqueous solution, cobalt phosphate, and bismuth phosphate, and the mass ratio of fine cotton straw powder: 10wt% H2SO4 aqueous solution: cobalt phosphate: bismuth phosphate is 1:4:0.2:0.03. After mixing, stir at 50°C for 4h; then place it in a hydration kettle, hydrate at 120°C for 5h, filter to obtain cobalt / bismuth-doped straw powder; place the powder in a tubular furnace, and calcine at 700°C in a nitrogen atmosphere for 8h to obtain catalyst 2.

[0051] Catalyst 3: Grind Egyptian cotton straw into powder with a particle size of 10 microns, add it to a beaker, and then add 1wt% HCl aqueous solution, cobalt chloride, and bismuth nitrate, and the mass ratio of Egyptian cotton straw powder: 3wt% HCl aqueous solution: cobalt chloride: bismuth nitrate is 1:5:0.25:0.04. After mixing, stir at 30°C for 5h; then place it in a hydration kettle, hydrate at 140°C for 4h, filter to obtain cobalt / bismuth-doped straw powder; place the powder in a tubular furnace, and calcine it at 800°C in a nitrogen atmosphere for 4h to obtain Catalyst 3.

[0052] Catalyst 4: Grind long-staple cotton stalks into powder with a particle size of 20 microns, add them into a beaker, and then add 3wt% HCl aqueous solution, cobalt nitrate, and bismuth nitrate, and the mass ratio of long-staple cotton stalk powder: 3wt% HCl aqueous solution: cobalt nitrate: bismuth nitrate is 1:4.5:0.5:0.06. After mixing, stir at 40°C for 6h; then place in a hydration kettle, hydrate at 150°C for 3h, filter to obtain cobalt / bismuth-doped straw powder; place the powder in a tubular furnace, and calcine at 750°C in a nitrogen atmosphere for 10h to obtain catalyst 4.

[0053] Example 2

[0054] CBDK catalytic hydrogenation to CBDO:

[0055] 1000 g of 4 wt% CBDK isobutyl isobutyrate solution was added to a reactor, 0.8 g of catalyst 1 was added, and hydrogen was introduced for hydrogenation reaction. The reaction temperature was 150° C., the reaction pressure gauge pressure was 4 MPa, the reaction was continued for 4 h, and sampling was performed for testing. The conversion rate of CBDK was 99.9%, the selectivity of CBDO was 99.3%, and the ratio of cis-trans isomers of CBDO was 43.7.

[0056] Catalyst 1 was recovered by filtration from the reaction solution. After 110 uses, the conversion rate of CBDK was 99.9%, the selectivity of CBDO was 99.2%, and the ratio of cis-trans isomers of CBDO was 43.5.

[0057] Example 3

[0058] 1000 g of 5 wt% CBDK isobutyl isobutyrate solution was added to the reactor, 0.025 g of catalyst 2 was added, and hydrogen was introduced for hydrogenation reaction. The reaction temperature was 180° C., the reaction pressure gauge pressure was 1 MPa, the reaction was continued for 1 h, and sampling was performed for testing. The conversion rate of CBDK was 99.6%, the selectivity of CBDO was 99.3%, and the ratio of cis-trans isomers of CBDO was 34.1.

[0059] Catalyst 2 was recovered by filtration from the reaction solution. After the catalyst was used 134 times, the conversion rate of CBDK was 99.5%, the selectivity of CBDO was 99.1%, and the ratio of cis-trans isomers of CBDO was 32.7.

[0060] Example 4

[0061] 1000 g of 8 wt % CBDK isobutyl isobutyrate solution was added to a reactor, 0.8 g of catalyst 3 was added, and hydrogen was introduced for hydrogenation reaction. The reaction temperature was 140° C., the reaction pressure gauge pressure was 3 MPa, the reaction was continued for 6 h, and sampling was performed for testing. The conversion rate of CBDK was 99.8%, the selectivity of CBDO was 99.6%, and the ratio of cis-trans isomers of CBDO was 38.3.

[0062] Catalyst 3 was recovered by filtration from the reaction solution. After the catalyst was used 132 times, the conversion rate of CBDK was 99.7%, the selectivity of CBDO was 99.5%, and the ratio of cis-trans isomers of CBDO was 37.8.

[0063] Example 5

[0064] 1000 g of 1 wt% CBDK isobutyl isobutyrate solution was added to a reactor, 0.5 g of catalyst 4 was added, and hydrogen was introduced for hydrogenation reaction. The reaction temperature was 100° C., the reaction pressure gauge pressure was 5 MPa, the reaction was carried out for 8 h, and sampling was tested. The conversion rate of CBDK was 99.9%, the selectivity of CBDO was 99.8%, and the ratio of cis-trans isomers of CBDO was 52.6.

[0065] Catalyst 4 was recovered by filtration from the reaction solution. After the catalyst was used 107 times, the conversion rate of CBDK was 99.8%, the selectivity of CBDO was 99.6%, and the ratio of cis-trans isomers of CBDO was 52.6.

[0066] Comparative Example 1

[0067] The preparation method of catalyst 1 was referred to, except that the raw material was replaced by activated carbon powder instead of cotton straw, and other operations and conditions remained unchanged, to obtain catalyst 5.

[0068] Catalyst 5 was used in place of catalyst 1 in Example 2. The other reaction conditions were the same as those in Example 2. The conversion rate of CBDK when the catalyst was used for the first time was 92.4%, the selectivity of CBDO was 98.9%, and the ratio of cis-trans isomers of CBDO was 1.4.

[0069] Catalyst 5 was recovered by filtration from the reaction solution. After the catalyst was used 50 times, the conversion rate of CBDK was 91.8%, the selectivity of CBDO was 96.7%, and the ratio of cis-trans isomers of CBDO was 1.28.

[0070] Comparative Example 2

[0071] The preparation method of catalyst 1 was referred to, except that bismuth acetate was not added to the raw materials, and other operations and conditions remained unchanged, to obtain catalyst 6.

[0072] Catalyst 6 was used in place of catalyst 1 in Example 2. The other reaction conditions were the same as those in Example 2. The conversion rate of CBDK was 99.1% when the catalyst was used for the first time. The selectivity of CBDO was 99.3%. The ratio of cis-trans isomers of CBDO was 37.8.

[0073] Catalyst 6 was recovered by filtration from the reaction solution. After the catalyst was used 50 times, the conversion rate of CBDK was 95.4%, the selectivity of CBDO was 98.7%, and the ratio of cis-trans isomers of CBDO was 28.9.

[0074] It is easy to understand that the above embodiments are only examples for clear explanation and do not mean that the present invention is limited thereto. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from this are still within the protection scope of the present invention.

Claims

1. A hydrogenation catalyst, characterized in that The catalyst is a nitrogen-doped carbon nanotube-supported metal cobalt / bismuth catalyst.

2. A method for preparing the nitrogen-doped carbon nanotube-supported metal cobalt / bismuth catalyst according to claim 1, characterized in that the steps include: 1) Grinding cotton straw into powder, adding acid solution, cobalt salt and bismuth salt and stirring, then performing hydration reaction, and filtering to obtain cobalt / bismuth doped straw powder; 2) The cobalt / bismuth doped straw powder is calcined in a nitrogen atmosphere to obtain the nitrogen-doped carbon nanotube-loaded metal cobalt / bismuth catalyst.

3. The preparation method according to claim 2, characterized in that: Step 1) the cotton straw is one or more of long-staple cotton straw, fine-staple cotton straw, and Egyptian cotton straw, preferably long-staple cotton straw; Preferably, the cotton straw is ground into a powder with a particle size of 1.5-20 microns.

4. The preparation method according to claim 2, characterized in that: Step 1) The acid solution is an aqueous solution of an acid, and the concentration is preferably 1-10 wt%; Preferably, the acid is selected from inorganic acids, preferably one or more of hydrochloric acid and sulfuric acid.

5. The preparation method according to claim 2, characterized in that: Step 1) the cobalt salt is selected from one or more of cobalt nitrate, cobalt phosphate and cobalt chloride; and / or In step 1), the bismuth salt is selected from one or more of bismuth nitrate, bismuth phosphate and bismuth acetate.

6. The preparation method according to claim 2, characterized in that: Step 1) The mass ratio of the cotton straw to the acid solution, the cobalt salt, and the bismuth salt is 1:(3-5):(0.2-0.5):(0.03-0.08); and / or In step 1), the stirring temperature is 20-50° C. and the stirring time is 4-8 h.

7. The preparation method according to claim 2, characterized in that: Step 2) the hydration reaction is carried out at a temperature of 100-150° C. for 3-6 hours; and / or In step 2), the calcination temperature is 600-800° C. and the calcination time is 4-12 hours.

8. A method for preparing 2,2,4,4-tetramethyl-1,3-cyclobutanediol by hydrogenating 2,2,4,4-tetramethyl-1,3-cyclobutanedione, characterized in that: The method uses 2,2,4,4-tetramethyl-1,3-cyclobutanedione and hydrogen as raw materials, and performs a hydrogenation reaction in a solvent environment under the catalysis of a hydrogenation catalyst to obtain the 2,2,4,4-tetramethyl-1,3-cyclobutanediol; The hydrogenation catalyst is the nitrogen-doped carbon nanotube-supported metal cobalt / bismuth catalyst according to claim 1 or the nitrogen-doped carbon nanotube-supported metal cobalt / bismuth catalyst prepared by the method according to any one of claims 2-7.

9. The method according to claim 8, characterized in that The solvent is selected from one or more of cyclohexane, isobutyl isobutyrate, and methyl isobutyl ketone, preferably isobutyl isobutyrate; and / or The concentration of 2,2,4,4-tetramethyl-1,3-cyclobutanedione in the solvent is 1-8 wt %; and / or The amount of the hydrogenation catalyst used is 0.05-5 wt % based on the total mass of 2,2,4,4-tetramethyl-1,3-cyclobutanedione and the solvent.

10. The method according to claim 8, characterized in that The hydrogenation reaction has a reaction temperature of 100-180° C., preferably 120-150° C., a reaction pressure of 1-5 MPa, preferably 1-3 MPa, and a reaction time of 1-8 h, preferably 2-4 h.