A catalyst for preparing dimethyl carbonate by gas-phase decarboxylation of dimethyl oxalate and a preparation method thereof

Abstract

This application belongs to the field of chemical technology, specifically disclosing a catalyst and its preparation method for the gas-phase decarbonylation of dimethyl oxalate to dimethyl carbonate. The catalyst for dimethyl oxalate decarbonylation is a supported solid base catalyst, comprising a support and an active component and / or active agent supported on the support. The active component is an alkali metal carbonate, and the active agent is a transition metal carbonate. The catalyst disclosed in this application has a simple preparation method and is easy to use. It exhibits excellent reactivity in the decarbonylation reaction of dimethyl oxalate. When used in a gas-phase system to achieve the decarbonylation reaction of dimethyl oxalate, it demonstrates excellent conversion and selectivity, achieving a DMO conversion rate close to 100% and a DMC selectivity higher than 95%. Furthermore, it can be recycled multiple times and is suitable for various industrial reaction facilities such as fixed-bed reactors and batch reactors.

Description

Technical Field

[0001] This application belongs to the field of chemical technology, specifically a catalyst for the gas-phase decarbonylation of dimethyl oxalate to prepare dimethyl carbonate and its preparation method. Background Technology

[0002] Dimethyl carbonate (DMC) is a non-toxic, environmentally friendly, and widely used chemical raw material. It is an important organic synthesis intermediate containing carbonyl, methyl, and methoxy functional groups in its molecular structure, exhibiting diverse reactivity. Its production is characterized by safety, convenience, low pollution, and easy transportation. Due to its relatively low toxicity, DMC is a promising "green" chemical product. Currently, there are various methods for synthesizing DMC, such as the traditional phosgene process, the actively researched transesterification method, and the urea alcoholysis method. However, these methods all have drawbacks, potentially causing environmental pollution or wasting raw materials.

[0003] Furthermore, my country's coal production ranks among the world's top, making it a major coal producer. Research and development of products related to coal chemical engineering has always been a focus of attention. For example, ethylene glycol is synthesized via the coal-to-chemicals route, yielding dimethyl oxalate as an intermediate. However, the poor quality of ethylene glycol synthesized via this route makes it difficult to meet the requirements of downstream products, leading to an overcapacity of dimethyl oxalate. Simultaneously, with the increasing substitution role of carbonates in gasoline oxygenated additives and the surge in demand for lithium-ion batteries, domestic dimethyl carbonate production capacity is significantly insufficient. Therefore, converting dimethyl oxalate into dimethyl carbonate is a value-added route that can simultaneously address both the domestic overcapacity of dimethyl oxalate and the insufficient supply of dimethyl carbonate.

[0004] There are few reports on methods for converting oxalate esters to carbonate esters via direct decarbonylation reactions. In this process, the catalyst is crucial to the success of the reaction. Early researchers explored the catalytic conversion of diaryl oxalate to diaryl carbonate, with metal ion acetates such as Mn(OAc)₂, Ce(OAc)₂, Zn(OAc)₂, and Ca(OAc)₂ as the main catalysts, achieving yields of 20-40%. Zhang Haoyang reported on the use of solid base catalysts for the decarbonylation of dimethyl oxalate to dimethyl carbonate, employing alkali metal carbonates as active components and activated carbon or carbon nanotubes as supports. When using rubidium carbonate / activated carbon catalysts or carbon nanotubes as supports, both selectivity and conversion rates were very high. However, when using alkali metal carbonates such as potassium carbonate and sodium carbonate as supports and activated carbon as supports, the conversion rate was only around 60%.

[0005] Since there has been no in-depth research or detailed reporting on the method of directly producing dimethyl carbonate from dimethyl oxalate through decarbonylation, and the preparation method of its catalyst, both domestically and internationally, it is of great significance to explore highly active and selective catalysts to achieve liquid-phase decarbonylation for the preparation of carbonate products such as dimethyl carbonate. Summary of the Invention

[0006] To address the problems of the prior art, this application provides a catalyst for the gas-phase decarbonylation of dimethyl oxalate to prepare dimethyl carbonate and a method thereof, which is achieved through the following scheme:

[0007] A catalyst for the gas-phase decarbonylation of dimethyl oxalate to dimethyl carbonate is disclosed. The catalyst for the decarbonylation of dimethyl oxalate is a supported solid base catalyst. The supported solid base catalyst includes a support and an active component and / or an active auxiliary agent supported on the support. The active component is an alkali metal carbonate, and the active auxiliary agent is a transition metal carbonate.

[0008] Furthermore, the support is active alumina; the general formula of the supported solid base catalyst is M1-M2 / Al2O3.

[0009] Furthermore, the loading amount of the active component is 10wt% to 40wt%, and the loading amount of the active adjuvant is 10wt% to 40wt%.

[0010] Furthermore, in the general formula, M1 is the active component, and the alkali metal carbonate is one or both of cesium carbonate and rubidium carbonate.

[0011] Furthermore, in the general formula, M2 is an active additive, and the transition metal carbonates La and Ce carbonates are one or both.

[0012] A method for preparing a catalyst for the gas-phase decarbonylation of dimethyl oxalate to dimethyl carbonate, wherein the catalyst is prepared by a co-deposition precipitation method followed by an equal-volume impregnation method, and the preparation steps are as follows:

[0013] Step S1 Transition metal carbonate loading: Nanoscale alumina is activated at high temperature to obtain an active alumina support. An aqueous solution of a transition metal soluble salt and an aqueous solution of a precipitant are prepared. The support is placed in a reaction apparatus, and the aqueous solutions of the soluble salt and the precipitant are added to the reaction apparatus in parallel flow. During this process, the mixture is stirred vigorously. After the solution is completely added, the mixture is stirred vigorously for 2 to 10 hours. After filtration, washing, drying, and calcination, the modified support M2 / Al2O3 is obtained.

[0014] Step S2 Alkali metal carbonate loading: Prepare an aqueous solution of alkali metal carbonate with a mass concentration of 15% to 30%, impregnate the above modified support M2 / Al2O3 with an equal volume, dry and calcine to obtain catalyst M1-M2 / Al2O3 for gas-phase decarbonylation of dimethyl oxalate.

[0015] Furthermore, in step S1, the activation temperature is 750-850℃, and the activation time is 4-6h; the stirring rate is 500-1000r / min; during the concurrent addition of the two solutions, the pH value in the reaction apparatus is controlled to be 8-10 by adjusting the rate of adding the aqueous solution of the soluble salt and / or the aqueous solution of the precipitant; the addition rate of the aqueous solution of the soluble salt is 0.7-1.2ml / min, the addition rate of the aqueous solution of the precipitant is 0.7-1.2ml / min, and the addition rates of the aqueous solution of the soluble salt and the aqueous solution of the precipitant may be the same or different.

[0016] Furthermore, in step S1, the transition metal soluble salt is one or more of La(NO3)3·6H2O, Ce(NO3)3·6H2O, LaCl3·7H2O, and CeCl3·7H2O. The mass concentration of the aqueous solution of the transition metal soluble salt is 5wt% to 10wt%. The precipitant is sodium bicarbonate, and the mass concentration of the aqueous solution of the precipitant is 5wt% to 10wt%. When the solution is added in parallel, the temperature inside the reaction device is controlled at 70°C. The temperature during aging is 80°C. Calcination is carried out at 450 to 800°C under a CO2 atmosphere for 3-6 hours.

[0017] Furthermore, in step S2, the drying temperature is 50–110°C and the drying time is 8–12 h, while the calcination is carried out in an air atmosphere at a temperature of 450–600°C for 3–6 h.

[0018] Furthermore, dimethyl oxalate and the catalyst are placed in a batch reactor, with the amount of catalyst added being 5-20 wt% of dimethyl oxalate. The reaction is carried out at 180-220°C and 2.0-6.0 MPa for 1.5-8 hours. Before the reaction, the air in the batch reactor is replaced with nitrogen.

[0019] Beneficial effects: This invention provides a catalyst system and preparation method for the direct gas-phase decarbonylation of dimethyl oxalate to dimethyl carbonate. This catalyst system is simple to prepare and use, and exhibits good reactivity in the decarbonylation reaction of dimethyl oxalate. When used in a gas-phase system to achieve the decarbonylation reaction of dimethyl oxalate, it achieves excellent conversion and selectivity, reaching a DMO conversion rate of nearly 100% and a DMC selectivity of over 95%. It can also be recycled multiple times and is suitable for various industrial reaction facilities such as fixed-bed reactors and batch reactors. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some preferred embodiments of this application, and not all embodiments. For those skilled in the art, other embodiments and drawings can be obtained based on these embodiments and drawings without creative effort, and all of them fall within the protection scope of this application.

[0021] Figure 1 The X-ray powder diffraction pattern of the Cs2CO3-La2(CO3)3 / Al2O3 catalyst in Example 3;

[0022] Figure 2 The X-ray powder diffraction pattern of the Cs2CO3-Ce2(CO3)3 / Al2O3 catalyst in Example 5;

[0023] Figure 3 A schematic diagram of the apparatus for the gas-phase decarbonylation of dimethyl oxalate to prepare dimethyl carbonate;

[0024] In the diagram, 1 is a nitrogen cylinder, 2 is a magnetic stirrer, 3 is a heating jacket, 4 is the main body of the device, 5 is a magnetic stir bar, 6 is a feed valve, 7 is a pressure gauge, and 8 is a temperature controller. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments of this application will be described in further detail below. It should be understood that the terms "upper," "lower," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. The foregoing definitions are only for the convenience of describing this application and simplifying the description, and are not intended to indicate or imply that the structure referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0026] Example 1

[0027] Catalyst preparation: ① Using boehmite as a support, calcined at 800℃ in air before use; ② Prepare a 5wt% La(NO3)3 aqueous solution and an excess of NaHCO3 solution (5wt%). Place the support from step ① in a precipitation tank. After the temperature in the tank stabilizes at 70℃, slowly add the two solutions together in parallel dropwise into the precipitation tank, controlling the pH value of the precipitation to 8-10, and continuously stirring vigorously; after the addition is complete, raise the temperature to 80℃ and continue stirring vigorously for aging for 2-10 hours; after filtration, washing, and drying, calcined at 600℃ for 3 hours in a 90% CO2 N2 atmosphere to obtain the modified support La2(CO3)3-Al2O3.

[0028] Reaction Evaluation: 12g of dimethyl oxalate and 1.2g of the catalyst prepared above (10% of the mass of DMO) were charged into a stainless steel high-pressure reactor. After sealing the reactor, its airtightness was tested by pressurizing. If the airtightness was good, the gas inside the reactor was purged with high-purity nitrogen at least three times, then vented. A thermocouple was inserted, stirring was started, and the temperature was raised to the reaction temperature of 210℃. The reaction was carried out for 8 hours. After natural cooling to room temperature, the gas was collected using a gas bag. After the gas was completely discharged, the reactor lid was opened, and the liquid product at the bottom of the reactor was obtained. The bottom liquid was analyzed by gas chromatography. The analysis showed that the conversion rate of dimethyl oxalate was 33.45%, and the selectivity of dimethyl carbonate was 51.57%.

[0029] Example 2

[0030] Catalyst preparation: ① Using boehmite as a support, calcined at 800℃ in air before use; ② Prepare a 5wt% CeCl3 aqueous solution and an excess of 5wt% NaHCO3 solution. Place the support from step ① in a precipitation tank. After the temperature in the tank stabilizes at 70℃, slowly add both solutions together in parallel dropwise into the precipitation tank, controlling the pH value of the precipitation to 8-10, and continuously stirring vigorously; after the addition is complete, raise the temperature to 80℃ and continue stirring vigorously for aging for 2-10 hours; after filtration, washing, and drying, calcined at 600℃ for 3 hours in a CO2 atmosphere to obtain the modified support Ce2(CO3)3-Al2O3.

[0031] Reaction evaluation: The reaction was evaluated in the same stainless steel high-pressure reactor as in Example 1, with a catalyst mass ratio of 20% (based on the mass of dimethyl oxalate), a reaction temperature of 220°C, and a reaction time of 6 hours. Analysis showed that the conversion rate of dimethyl oxalate was 30.98%, and the selectivity for dimethyl carbonate was 50.79%.

[0032] Example 3

[0033] Catalyst preparation: ① Using boehmite as a support, calcined at 800℃ in air before use; ② Prepare a 5wt% La(NO3)3 aqueous solution and an excess of 5wt% NaHCO3 solution. Place the support from step ① in a precipitation tank. After the temperature in the tank stabilizes at 70℃, slowly add both solutions dropwise together in parallel, controlling the pH of the precipitation to 8-10 while continuously and vigorously stirring; after the addition is complete, raise the temperature to 80℃ and continue vigorous stirring. The catalyst was aged by vigorous stirring for 2-10 hours; after filtration, washing, and drying, it was calcined at 600℃ for 3 hours under a CO2 atmosphere to obtain the modified support La2(CO3)3 / Al2O3; ③ At room temperature, a 25% (Cs2CO3 / H2O) cesium carbonate aqueous solution was prepared, and the above La2(CO3)3 / Al2O3 support was impregnated with an equal volume. After standing and drying, it was calcined at 450℃ for 3 hours under a CO2 atmosphere to obtain the Cs2CO3-La2(CO3)3 / Al2O3 catalyst.

[0034] Reaction evaluation: The reaction was evaluated in the same stainless steel high-pressure reactor as in Example 1, with a catalyst mass ratio of 10% (based on the mass of dimethyl oxalate), a reaction temperature of 210℃, and a reaction time of 8 hours. Analysis showed that the conversion rate of dimethyl oxalate was 99.77%, and the selectivity for dimethyl carbonate was 96.8%.

[0035] Example 4

[0036] Catalyst preparation: ① Using boehmite as a support, calcined at 800℃ in air before use; ② Prepare a 5wt% La(NO3)3 aqueous solution and an excess of 5wt% NaHCO3 solution. Place the support from step ① in a precipitation tank. After the temperature in the tank stabilizes at 70℃, slowly add both solutions dropwise together in parallel, controlling the pH of the precipitation to 8-10 while continuously and vigorously stirring; after the addition is complete, raise the temperature to 80℃ and continue vigorous stirring for aging for 2 days. ~10h; After filtration, washing, and drying, the modified support La2(CO3)3 / Al2O3 was obtained by calcination at 600℃ for 3h under a N2 atmosphere of 30% CO2; ③ At room temperature, a 15% (Rb2CO3 / H2O) rubidium carbonate aqueous solution was prepared, and the above La2(CO3)3 / Al2O3 support was impregnated with an equal volume. After standing and drying, the catalyst was obtained by calcination at 450℃ for 3h under a N2 atmosphere of 30% CO2.

[0037] Reaction evaluation: The reaction was evaluated in the same stainless steel high-pressure reactor as in Example 1, with a catalyst mass ratio of 15% (based on the mass of dimethyl oxalate), a reaction temperature of 220°C, and a reaction time of 6 hours. Analysis showed that the conversion rate of dimethyl oxalate was 99.56%, and the selectivity for dimethyl carbonate was 94.27%.

[0038] Example 5

[0039] Catalyst preparation: ① Using boehmite as a support, calcined at 800℃ in air before use; ② Prepare a 5wt% Ce(NO3)3 aqueous solution and an excess of 5wt% NaHCO3 solution. Place the support from step ① in a precipitation tank. After the temperature in the tank stabilizes at 70℃, slowly add both solutions dropwise together in parallel, controlling the pH of the precipitation to 8-10 while continuously and vigorously stirring; after the addition is complete, raise the temperature to 80℃ and continue vigorous stirring for aging for 2 days. ~10h; After filtration, washing, and drying, the modified support Ce2(CO3)3 / Al2O3 was obtained by calcination at 600℃ for 3h under a N2 atmosphere of 50% CO2; ③ At room temperature, a 15% (Cs2CO3 / H2O) cesium carbonate aqueous solution was prepared, and the above Ce2(CO3)3 / Al2O3 support was impregnated with an equal volume. After standing and drying, the catalyst was calcined at 450℃ for 3h under a N2 atmosphere of 50% CO2 to obtain Cs2CO3-Ce2(CO3)3 / Al2O3 catalyst.

[0040] Reaction evaluation: The reaction was evaluated in the same stainless steel high-pressure reactor as in Example 1, with a catalyst mass ratio of 15% (based on the mass of dimethyl oxalate), a reaction temperature of 200℃, and a reaction time of 6 hours. Analysis showed that the conversion rate of dimethyl oxalate was 99.43%, and the selectivity for dimethyl carbonate was 94.7%.

[0041] Example 6

[0042] Catalyst preparation: ① Using boehmite as a support, calcined at 800℃ in air before use; ② Prepare a 5wt% Ce(NO3)3 aqueous solution and an excess of 5wt% NaHCO3 solution. Place the support from step ① in a precipitation tank. After the temperature in the tank stabilizes at 70℃, slowly add both solutions dropwise together in parallel, controlling the pH of the precipitation to 8-10 while continuously and vigorously stirring; after the addition is complete, raise the temperature to 80℃ and continue vigorous stirring for aging for 2 days. ~10h; After filtration, washing, and drying, the modified support Ce2(CO3)3 / Al2O3 was obtained by calcination at 600℃ for 3h under a N2 atmosphere of 60% CO2; ③ At room temperature, a 20% (Rb2CO3 / H2O) rubidium carbonate aqueous solution was prepared, and the above Ce2(CO3)3 / Al2O3 support was impregnated with an equal volume. After standing and drying, the catalyst was calcined at 450℃ for 3h under a N2 atmosphere of 60% CO2 to obtain Rb2CO3-Ce2(CO3)3 / Al2O3 catalyst.

[0043] Reaction evaluation: The reaction was evaluated in the same stainless steel high-pressure reactor as in Example 1, with a catalyst mass ratio of 10% (based on the mass of dimethyl oxalate), a reaction temperature of 210℃, and a reaction time of 6 hours. Analysis showed that the conversion rate of dimethyl oxalate was 99.27%, and the selectivity for dimethyl carbonate was 95.1%.

[0044] Example 7

[0045] Catalyst preparation: ① Using boehmite as a support, calcined at 800℃ in air before use; ② Prepare an 8wt% LaCl3 aqueous solution and an excess of 8wt% NaHCO3 solution. Place the support from step ① in a precipitation tank. After the temperature in the tank stabilizes at 70℃, slowly add both solutions dropwise together in parallel, controlling the pH of the precipitation to 8-10 while continuously and vigorously stirring; after the addition is complete, raise the temperature to 80℃ and continue vigorous stirring. Aged for 2-10 hours; after filtration, washing, and drying, calcined at 600℃ for 3 hours under CO2 atmosphere to obtain the modified support La2(CO3)3 / Al2O3; ③ At room temperature, a 25% (Cs2CO3 / H2O) cesium carbonate aqueous solution was prepared, and the above La2(CO3)3 / Al2O3 support was impregnated with an equal volume. After standing and drying, it was calcined at 450℃ for 3 hours under CO2 atmosphere to obtain the Cs2CO3-La2(CO3)3 / Al2O3 catalyst.

[0046] Reaction evaluation: The reaction was evaluated in the same stainless steel high-pressure reactor as in Example 1, with a catalyst mass ratio of 15% (based on the mass of dimethyl oxalate), a reaction temperature of 210℃, and a reaction time of 8 hours. Analysis showed that the conversion rate of dimethyl oxalate was 99.47%, and the selectivity for dimethyl carbonate was 96.6%.

[0047] Example 8

[0048] Catalyst preparation: ① Using boehmite as a support, calcined at 800℃ in air before use; ② Prepare a 7wt% LaCl3 aqueous solution and an excess of 7wt% NaHCO3 solution. Place the support from step ① in a precipitation tank. After the tank temperature stabilizes at 70℃, slowly add both solutions dropwise together in parallel, controlling the pH of the precipitation to 8-10 while continuously and vigorously stirring; after the addition is complete, raise the temperature to 80℃ and continue vigorous stirring for aging for 2-1 days. 0h; After filtration, washing, and drying, the modified support La2(CO3)3 / Al2O3 was obtained by calcination at 600℃ for 3h under a N2 atmosphere of 90% CO2; ③ At room temperature, a 25% (Rb2CO3 / H2O) rubidium carbonate aqueous solution was prepared, and the above La2(CO3)3 / Al2O3 support was impregnated with an equal volume. After standing and drying, the catalyst was obtained by calcination at 450℃ for 3h under a N2 atmosphere of 90% CO2.

[0049] Reaction evaluation: The reaction was evaluated in the same stainless steel high-pressure reactor as in Example 1, with a catalyst mass ratio of 10% (based on the mass of dimethyl oxalate), a reaction temperature of 200℃, and a reaction time of 8 hours. Analysis showed that the conversion rate of dimethyl oxalate was 99.21%, and the selectivity for dimethyl carbonate was 96.12%.

[0050] Example 9

[0051] Catalyst preparation: ① Using boehmite as a support, calcined at 800℃ in air before use; ② Prepare a 10wt% CeCl3 aqueous solution and an excess of 10wt% NaHCO3 solution. Place the support from step ① in a precipitation tank. After the temperature in the tank stabilizes at 70℃, slowly add both solutions dropwise together in parallel, controlling the pH of the precipitation to 8-10 while continuously and vigorously stirring; after the addition is complete, raise the temperature to 80℃ and continue vigorous stirring for aging for 2-3 days. 10h; After filtration, washing, and drying, the modified support Ce2(CO3)3 / Al2O3 was obtained by calcination at 600℃ for 3h under a N2 atmosphere of 90% CO2; ③ At room temperature, a 30% (Cs2CO3 / H2O) cesium carbonate aqueous solution was prepared, and the above Ce2(CO3)3 / Al2O3 support was impregnated with an equal volume. After standing and drying, the catalyst was calcined at 450℃ for 3h under a N2 atmosphere of 90% CO2 to obtain Cs2CO3-Ce2(CO3)3 / Al2O3 catalyst.

[0052] Reaction evaluation: The reaction was evaluated in the same stainless steel high-pressure reactor as in Example 1, with a catalyst mass ratio of 20% (based on the mass of dimethyl oxalate), a reaction temperature of 220°C, and a reaction time of 4 hours. Analysis showed that the conversion rate of dimethyl oxalate was 99.43%, and the selectivity for dimethyl carbonate was 96.38%.

[0053] Example 10

[0054] Catalyst preparation: ① Using boehmite as a support, calcined at 800℃ in air before use; ② Prepare a 5wt% CeCl3 aqueous solution and an excess of 5wt% NaHCO3 solution. Place the support from step ① in a precipitation tank. After the temperature in the tank stabilizes at 70℃, slowly add both solutions dropwise together in parallel, controlling the pH of the precipitation to 8-10 while continuously and vigorously stirring; after the addition is complete, raise the temperature to 80℃ and continue vigorous stirring for aging for 2-1 days. 0h; After filtration, washing, and drying, the modified support Ce2(CO3)3 / Al2O3 was obtained by calcination at 600℃ for 3h under an N2 atmosphere of 80% CO2; ③ At room temperature, a 15% (Rb2CO3 / H2O) rubidium carbonate aqueous solution was prepared, and the above Ce2(CO3)3 / Al2O3 support was impregnated with an equal volume. After standing and drying, the catalyst was calcined at 450℃ for 3h under an N2 atmosphere of 80% CO2 to obtain the Rb2CO3-Ce2(CO3)3 / Al2O3 catalyst.

[0055] Reaction evaluation: The reaction was evaluated in the same stainless steel high-pressure reactor as in Example 1, with a catalyst mass ratio of 20% (based on the mass of dimethyl oxalate), a reaction temperature of 210℃, and a reaction time of 6 hours. Analysis showed that the conversion rate of dimethyl oxalate was 99.29%, and the selectivity for dimethyl carbonate was 95.86%.

[0056] Table 1

[0057]

[0058]

[0059] Note: The percentage of catalyst added is based on the mass of dimethyl oxalate, the raw material.

[0060] Example 11

[0061] Catalyst preparation: The Cs2CO3-La / Al2O3 catalyst of Example 3 was used.

[0062] Reaction evaluation: The reaction was evaluated in the same stainless steel high-pressure reactor as in Example 3. The catalyst mass ratio was 10% (based on the mass of dimethyl oxalate), the reaction temperature was 210℃, and the reaction time was 8 hours. The experiment was repeated 10 times. The experimental results are shown in Table 2 below after chromatographic analysis.

[0063] Table 2

[0064]

[0065] Example 12

[0066] like Figure 3As shown, an apparatus for the gas-phase decarbonylation of dimethyl oxalate to prepare dimethyl carbonate includes an apparatus body 4. The upper part of the apparatus body 4 is connected to a nitrogen cylinder 1 via a displacement pipe. A displacement valve is provided on the displacement pipe. The apparatus body 4 has a feed inlet with a feed valve 6. The lower part of the apparatus body 4 has an outlet valve and a discharge outlet. A magnetic stirrer 2 is provided at the bottom of the apparatus body 4. A magnetic stir bar 5 that cooperates with the magnetic stirrer 2 is provided inside the apparatus body 4. A pressure gauge 7 and a temperature controller 8 are provided on the apparatus body. A heating jacket 3 is provided on the outside of the apparatus body 4.

[0067] Example 13

[0068] Based on Example 12, the device body is equipped with a waste gas discharge pipe, which is connected to a sedimentation tank containing lime water. The waste gas discharge pipe extends below the surface of the lime water. The sedimentation tank is connected to a filtration device via a pipeline. The filtration device is connected to a carbon dioxide generating device via a pipe. The carbon dioxide generating device contains dilute hydrochloric acid and is equipped with a carbon dioxide collection bottle. The carbon dioxide collection bottle is connected to the roasting device used in step S1 via a carbon dioxide delivery pipe. The carbon dioxide delivery pipe contains a desiccant. The sedimentation tank is connected to a waste gas collection system, and the filtration device is connected to the sedimentation tank via a return pipe.

[0069] The main exhaust gases discharged from the main body of the device through the exhaust pipe are carbon monoxide, carbon dioxide, and nitrogen. The exhaust gases enter the sedimentation tank through the exhaust pipe. Carbon dioxide reacts with the lime water in the sedimentation tank to produce calcium carbonate. Unreacted carbon monoxide and nitrogen are collected into the exhaust gas system for further treatment. The treatment of carbon monoxide and nitrogen is a conventional operation and will not be elaborated on here. The lime water after the reaction reaches the filtration device. The filtrate returns to the sedimentation tank through the return pipe to continue the reaction. The filter residue reaches the carbon dioxide generating device. The carbon dioxide generating device contains dilute hydrochloric acid. Calcium carbonate reacts with dilute hydrochloric acid to produce carbon dioxide gas. The carbon dioxide gas reaches the roasting device described in step S1 through the carbon dioxide delivery pipe for utilization.

[0070] Furthermore, the carbon dioxide generating device is a calcining furnace, where calcium carbonate is calcined to generate carbon dioxide, which is then transported through a carbon dioxide conveying pipe to the roasting device described in step S1 for use.

[0071] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application and are not intended to limit it. Although this application has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of this application without departing from the spirit and scope of the technical solutions of this application, and all such modifications or substitutions should be covered within the scope of the claims of this application.

Claims

1. A catalyst for the gas-phase decarbonylation of dimethyl oxalate to prepare dimethyl carbonate, characterized in that, The catalyst for the decarbonylation of dimethyl oxalate is a supported solid base catalyst. The supported solid base catalyst includes a support and an active component and an active promoter supported on the support. The active component is an alkali metal carbonate, and the active promoter is a transition metal carbonate. In the general formula, M2 is the active promoter, and the transition metal carbonate is one or both of La and Ce carbonates. The catalyst is prepared by a co-deposition precipitation method followed by an equal-volume impregnation method. The preparation steps are as follows: Step S1 Transition metal carbonate loading: Nanoscale alumina is activated at high temperature to obtain an active alumina support. An aqueous solution of a transition metal soluble salt and an aqueous solution of a precipitant are prepared. The support is placed in a reaction apparatus, and the aqueous solutions of the soluble salt and the precipitant are added to the reaction apparatus in parallel flow. During this process, the mixture is stirred vigorously. After the solution is completely added, the mixture is stirred vigorously for 2 to 10 hours. After filtration, washing, drying, and calcination, the modified support M2 / Al2O3 is obtained. Step S2 Alkali metal carbonate loading: Prepare an aqueous solution of alkali metal carbonate with a mass concentration of 15% to 30%, impregnate the above modified support M2 / Al2O3 with an equal volume, dry and calcine to obtain catalyst M1-M2 / Al2O3 for gas-phase decarbonylation of dimethyl oxalate.

2. The catalyst for the gas-phase decarbonylation of dimethyl oxalate to dimethyl carbonate according to claim 1, characterized in that, The support is active alumina; the general formula of the supported solid base catalyst is M1-M2 / Al2O3.

3. The catalyst for the gas-phase decarbonylation of dimethyl oxalate to dimethyl carbonate according to claim 1, characterized in that, The loading amount of the active component is 10wt% to 40wt%, and the loading amount of the active adjuvant is 10wt% to 40wt%.

4. The catalyst for the gas-phase decarbonylation of dimethyl oxalate to dimethyl carbonate according to claim 2, characterized in that, In the general formula, M1 is the active component, and the alkali metal carbonate is one or both of cesium carbonate and rubidium carbonate.

5. The catalyst for the gas-phase decarbonylation of dimethyl oxalate to dimethyl carbonate according to claim 1, characterized in that, In step S1, the activation temperature is 750-850℃, and the activation time is 4-6 hours; the stirring rate is 500-1000 r / min; during the parallel addition of the two solutions, the pH value in the reaction apparatus is controlled to be 8-10 by adjusting the rate of adding the aqueous solution of the soluble salt and / or the aqueous solution of the precipitant; the addition rate of the aqueous solution of the soluble salt is 0.7-1.2 ml / min, the addition rate of the aqueous solution of the precipitant is 0.7-1.2 ml / min, and the addition rates of the aqueous solution of the soluble salt and the aqueous solution of the precipitant may be the same or different.

6. The catalyst for the gas-phase decarbonylation of dimethyl oxalate to dimethyl carbonate according to claim 1, characterized in that, In step S1, the transition metal soluble salt is one or more of La(NO3)3·6H2O, Ce(NO3)3·6H2O, LaCl3·7H2O, and CeCl3·7H2O. The mass concentration of the aqueous solution of the transition metal soluble salt is 5wt% to 10wt%. The precipitant is sodium bicarbonate, and the mass concentration of the aqueous solution of the precipitant is 5wt% to 10wt%. The temperature inside the reaction apparatus is controlled at 70°C when the solution is added in parallel stream, and the temperature is 80°C during aging. Calcination is carried out at 450 to 800°C under a CO2 atmosphere for 3-6 hours.

7. The application method of the catalyst for the gas-phase decarbonylation of dimethyl oxalate to prepare dimethyl carbonate according to claim 5, characterized in that, Dimethyl oxalate and catalyst were placed in a batch reactor. The amount of catalyst added was 5-20 wt% of dimethyl oxalate. The reaction was carried out at 180-220℃ and 2.0-6.0 MPa for 1.5-8 hours. Before the reaction, the air in the batch reactor was replaced with nitrogen.

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