Pt-based catalyst as well as preparation method and application thereof
By using a Pt-supported sulfonated activated carbon catalyst, the environmental pollution and equipment corrosion problems in the traditional preparation of dimethyl terephthalate (DMT) have been solved, achieving a highly efficient and green DMT preparation with a yield of 87% and a selectivity of 95%.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-25
- Publication Date
- 2026-03-27
AI Technical Summary
Traditional methods for preparing dimethyl terephthalate (DMT) suffer from environmental pollution and equipment corrosion, and the process is not green or efficient enough.
Dimethyl terephthalate was prepared by using a Pt-supported sulfonated activated carbon catalyst via a series of esterification, Diels-Alder, and dehydrogenation reactions. The sulfonated activated carbon was used as a support and Pt was loaded as an active site to improve the reaction efficiency and selectivity.
It achieves a DMT yield of up to 87% and selectivity of over 95%, and the catalytic process is environmentally friendly, simple, and reduces the risk of equipment corrosion and pollution.
Abstract
Description
TECHNICAL FIELD
[0001] The application relates to a Pt-based catalyst and a preparation method and application thereof, and belongs to the field of catalysts. BACKGROUND
[0002] Dimethyl terephthalate (DMT) is a monomer of polyester. It is soluble in hot ethanol, methanol, diethyl ether, chloroform, and insoluble in water. It is mainly used for synthesizing polyester fibers, resins, films, polyester paints and engineering plastics. DMT is an important polyester raw material and is widely used. DMT can undergo ester exchange reaction with ethylene glycol, and then undergo polycondensation to generate the most important engineering plastic, PET, that is, DMT method is used to produce PET. DMT can be used to synthesize polybutylene adipate / terephthalate (PBAT) through ester exchange method, and has good heat resistance, plasticity and biodegradability. The ester exchange process condition of DTM is relatively mild, and the equipment requirement is not high, which is the mainstream process route for producing PBAT.
[0003] Traditionally, dimethyl terephthalate is prepared by using p-xylene as a raw material, and an air oxidation esterification method. Manganese acetate and cobalt acetate are used as catalysts, and metal bromide is used as an accelerator, so there are problems of environmental pollution and equipment corrosion. Improving the single-pass yield of DMT, using an environmentally friendly catalyst, using a non-polluting solvent, and adopting a low-energy and green process route are the goals of developing green chemical production technology of DMT. SUMMARY
[0004] The application provides a method for efficiently catalyzing the tandem esterification, Diels-Alder and dehydrogenation reaction of muconic acid (MA) with methanol and ethylene to prepare dimethyl terephthalate (DMT) by using a Pt-based catalyst. Compared with the traditional method, the method is environmentally friendly and simple and efficient.
[0005] In view of the above-mentioned route for preparing dimethyl terephthalate (DMT) from muconic acid (MA), the application provides a catalyst for efficiently catalyzing the tandem esterification, Diels-Alder and dehydrogenation reaction of MA to convert MA into DMT. The catalyst selects an acidified sulfonated activated carbon as a carrier and loads Pt on the carrier. Under the action of the catalyst, the yield of DMT is as high as 87%, and the selectivity is more than 95%.
[0006] According to one aspect of the application, a Pt-based catalyst is provided, characterized in that,
[0007] The Pt-based catalyst comprises a sulfonated activated carbon carrier and Pt loaded on the surface of the sulfonated activated carbon carrier; sulfonic acid groups serve as esterification reaction sites, and Pt loaded on the sulfonated carbon serves as a dehydrogenation reaction site.
[0008] wherein the loading of Pt is 0.5-10wt%.
[0009] According to another aspect of the present application, there is provided a method for preparing the Pt-based catalyst as described above, comprising the steps of:
[0010] immersing a sulfonated activated carbon carrier in a solution containing a Pt source, stirring, centrifuging, drying, reducing, to obtain the Pt-based catalyst.
[0011] the Pt source is selected from at least one of chloroplatinic acid, platinum nitrate;
[0012] the concentration of the Pt source in the solution containing the Pt source is 0.5-2mg / ml;
[0013] the solid-liquid ratio of the sulfonated activated carbon carrier to the solution containing the Pt source is 0.1-2:10mg / ml;
[0014] the solution containing the Pt source uses water and / or ethanol as solvent.
[0015] the drying is vacuum drying;
[0016] the temperature of the drying is 80-100℃;
[0017] the time of the drying is 6-12h;
[0018] the atmosphere of the reducing is hydrogen atmosphere;
[0019] the temperature of the reducing is 350-500℃;
[0020] the time of the reducing is 2-3h.
[0021] the sulfonated activated carbon carrier is obtained by the following steps:
[0022] mixing activated carbon with concentrated sulfuric acid (mass fraction of 98%), reacting, slowly dropping the reaction liquid into water for dilution, filtering, repeatedly washing with hot distilled water (>80℃), drying, to obtain the sulfonated activated carbon carrier.
[0023] the solid-liquid ratio of the activated carbon to the concentrated sulfuric acid is 0.5-1:10mg / ml;
[0024] the temperature of the reaction is 150-200℃;
[0025] the reaction is stirred under condensation reflux state;
[0026] the time of the reaction is 6-10h;
[0027] the temperature of the drying is 80-100℃;
[0028] The drying time is 12-24h.
[0029] According to another aspect of the present application, a method for preparing dimethyl terephthalate is provided, comprising the following steps:
[0030] In a nitrogen-replaced high-pressure reactor, ethylene gas is filled to the reaction pressure, and the mixture of muconic acid, methanol, solvent and catalyst is subjected to a dehydrogenation reaction to obtain dimethyl terephthalate;
[0031] The catalyst is the Pt-based catalyst described above.
[0032] The solvent is selected from at least one of water, dioxane, tetrahydrofuran and acetonitrile.
[0033] The mass ratio of the catalyst to muconic acid is 0.1-1:5;
[0034] The mass-volume ratio of muconic acid to solvent is 0.01-1:10 g / ml.
[0035] The temperature of the dehydrogenation reaction is 100-300℃;
[0036] The time of the dehydrogenation reaction is 0.5-10h;
[0037] The pressure of the dehydrogenation reaction is 0.1-5Mpa.
[0038] The beneficial effects that can be produced by the present application include:
[0039] 1) Compared with the homogeneous strong acid system, the present application has high requirements for the reaction equipment, is easy to cause equipment corrosion, and pollutes the environment with acid waste liquid. The present application modifies the acidic sulfonic acid group with a heterogeneous catalyst, is easy to separate, and is more environmentally friendly.
[0040] 2) Compared with the traditional method, the process flow is simple. DETAILED DESCRIPTION
[0041] The present application will be described in detail below in conjunction with examples, but the present application is not limited to these examples.
[0042] Unless otherwise specified, the raw materials and catalysts in the examples of the present application are purchased through commercial channels.
[0043] Preparation of material A in Example 1
[0044] (1) Take 2 g of activated carbon and add to 20 ml of H2SO4 (mass fraction of 98%), mix well, heat to 160°C, condense reflux reaction for 8 h, cool to room temperature. The reaction solution is slowly added to water dilution, filtration to get black solid, repeatedly washed with hot distilled water (> 80°C), finally the black solid is dried in an oven at 80°C, to obtain sulfonated carbon carrier.
[0045] (2) Take 1 g of acidified sulfonated carbon carrier and add to 10 ml of chloroplatinic acid ethanol solution with a concentration of 1 mg / ml, magnetic stirring for 12 h, rotary evaporation drying. Subsequently, the catalyst is reduced under hydrogen atmosphere at 350°C for 3 h. The sulfonated carbon catalyst loaded with Pt is obtained. The theoretical loading is 1 wt%. The catalyst A is obtained.
[0046] Preparation of material B in Example 2
[0047] (1) Take 2 g of activated carbon and add to 20 ml of H2SO4 (mass fraction of 98%), mix well, heat to 160°C, condense reflux reaction for 8 h, cool to room temperature. The reaction solution is slowly added to water dilution, filtration to get black solid, repeatedly washed with hot distilled water (> 80°C), finally the black solid is dried in an oven at 80°C, to obtain sulfonated carbon carrier.
[0048] (2) Take 0.5 g of acidified sulfonated carbon carrier and add to 10 ml of chloroplatinic acid ethanol solution with a concentration of 1 mg / ml, magnetic stirring for 12 h, rotary evaporation drying. Subsequently, the catalyst is reduced under hydrogen atmosphere at 350°C for 3 h. The sulfonated carbon catalyst loaded with Pt is obtained. The theoretical loading is 2 wt%. The catalyst B is obtained.
[0049] Preparation of material C in Example 3
[0050] (1) Take 2 g of activated carbon and add to 20 ml of H2SO4 (mass fraction of 98%), mix well, heat to 160°C, condense reflux reaction for 8 h, cool to room temperature. The reaction solution is slowly added to water dilution, filtration to get black solid, repeatedly washed with hot distilled water (> 80°C), finally the black solid is dried in an oven at 80°C, to obtain sulfonated carbon carrier.
[0051] (2) Take 1.5 g of acidified sulfonated carbon carrier and add to 10 ml of chloroplatinic acid ethanol solution with a concentration of 1 mg / ml, magnetic stirring for 12 h, rotary evaporation drying. Subsequently, the catalyst is reduced under hydrogen atmosphere at 350°C for 3 h. The sulfonated carbon catalyst loaded with Pt is obtained. The theoretical loading is 6 wt%. The catalyst C is obtained.
[0052] Example 4
[0053] Synthesized 0.02 g of catalyst A, 0.01 g of MA, 5 ml of methanol into a high-pressure reactor with 10 ml of solvent dioxane, replace the gas in the reactor with nitrogen, then replace with ethylene, fill in ethylene gas to the reaction pressure of 1 MPa. Heat to 150°C, magnetic stirring reaction for 4h. After the reaction, the conversion of MA and the selectivity of DMT are analyzed by GC, the conversion of MA is 72%, and the selectivity of DMT is 38%.
[0054] Example 5
[0055] Synthesized 0.01 g of catalyst B, 0.01 g of MA, 5 ml of methanol into a high-pressure reactor with 10 ml of solvent tetrahydrofuran, replace the gas in the reactor with nitrogen, then replace with ethylene, fill in ethylene gas to the reaction pressure of 3 MPa. Heat to 200°C, magnetic stirring reaction for 4h. After the reaction, the conversion of MA and the selectivity of DMT are analyzed by GC, the conversion of MA is 89%, and the selectivity of DMT is 78%.
[0056] Example 6
[0057] Synthesized 0.01 g of catalyst C, 0.02 g of MA, 5 ml of methanol into a high-pressure reactor with 10 ml of solvent tetrahydrofuran, replace the gas in the reactor with nitrogen, then replace with ethylene, fill in ethylene gas to the reaction pressure of 4 MPa. Heat to 250°C, magnetic stirring reaction for 6h. After the reaction, the conversion of MA and the selectivity of DMT are analyzed by GC, the conversion of MA is 91%, and the selectivity of DMT is 83%.
[0058] The above is only a few embodiments of the present application, not any form of the application to do any restrictions, although the preferred embodiments disclosed as above, however, not to limit the application, any skilled in the art, within the scope of the application without departing from the technical solution, using the above disclosed technical content to make some changes or modifications are equivalent to equivalent embodiments, all within the scope of the technical solution.
Claims
1. A Pt-based catalyst, characterized in that, The Pt-based catalyst comprises a sulfonated activated carbon support and Pt supported on the surface of the sulfonated activated carbon support. The loading of Pt is 0.5–10 wt%.
2. A method for preparing the Pt-based catalyst according to claim 1, characterized in that, Includes the following steps: The sulfonated activated carbon support was impregnated in a solution containing a Pt source, stirred, centrifuged, dried, and reduced to obtain the Pt-based catalyst.
3. The preparation method according to claim 2, characterized in that, The Pt source is selected from at least one of chloroplatinic acid and platinum nitrate. In the solution containing the Pt source, the concentration of the Pt source is 0.5–2 mg / ml; The solid-liquid ratio of the sulfonated activated carbon carrier to the solution containing the Pt source is 0.1–2:10 mg / ml; The solution containing the Pt source uses water and / or ethanol as solvents.
4. The preparation method according to claim 2, characterized in that, The drying process is vacuum drying; The drying temperature is 80–100°C; The drying time is 6–12 hours; The reducing atmosphere is a hydrogen atmosphere; The reduction temperature is 350–500°C; The reduction time is 2 to 3 hours.
5. The preparation method according to claim 2, characterized in that, The sulfonated activated carbon carrier is obtained through the following steps: Activated carbon is mixed with concentrated sulfuric acid and reacted. The reaction solution is then slowly added dropwise to water for dilution, filtered, washed with water, and dried to obtain the sulfonated activated carbon carrier.
6. The preparation method according to claim 5, characterized in that, The solid-liquid ratio of activated carbon to concentrated sulfuric acid is 0.5–1:10 mg / ml; The reaction temperature is 150–200°C; The reaction was carried out under reflux and stirring conditions. The reaction time is 6–10 hours; The drying temperature is 80–100°C; The drying time is 12 to 24 hours.
7. A method for preparing dimethyl terephthalate, characterized in that, Includes the following steps: In a reactor under an ethylene atmosphere, kojic acid, methanol, solvent and catalyst are mixed and a dehydrogenation reaction is carried out to obtain dimethyl terephthalate. The catalyst is the Pt-based catalyst according to claim 1.
8. The method according to claim 7, characterized in that, The solvent is selected from at least one of water, tetrahydrofuran, and acetonitrile.
9. The method according to claim 7, characterized in that, The mass ratio of the catalyst to kinematic acid is 0.1 to 1:5; The mass-to-volume ratio of the mucilage acid to the solvent is 0.01 to 1:10 g / ml.
10. The method according to claim 7, characterized in that, The temperature of the dehydrogenation reaction is 100–300°C; The dehydrogenation reaction takes 0.5 to 10 hours; The pressure of the dehydrogenation reaction is 0.1–5 MPa.