Catalyst for decarbonylation reaction, its preparation method and use

Abstract

The present invention relates to a catalyst for decarbonylation reaction, a preparation method thereof and a use thereof, which are used for preparing dialkyl carbonate by decarbonylating dialkyl oxalate. The catalyst contains two or more of alkali metals, alkaline earth metals and phosphorus, wherein the carrier is a nitrogen-modified carbon-based material.

Description

Technical Field

[0001] The present invention belongs to the field of chemical engineering, and specifically relates to a catalyst for decarbonylation reaction, a preparation method thereof, and uses thereof. Background Art

[0002] With the rapid development of the polycarbonate industry in recent years and the increasing development volume of new Li batteries, the demand for dimethyl carbonate (DMC) will surely increase gradually. The main methods for preparing DMC include the traditional phosgene method, transesterification method, methanol oxidative carbonylation method, etc. Among these methods, dimethyl oxalate directly undergoes decarbonylation under the action of a catalyst to generate dimethyl carbonate and a gaseous by-product CO. This process has low toxicity, cheap raw materials, no three wastes, high yield, low corrosion, and the by-product CO is also an important chemical product. This process route has the advantages of being green and environmentally friendly, high economic efficiency, etc., meets the requirements of modern green chemical industry development, and has received extensive attention.

[0003] Katsumasa Harada et al. of Ube Industries (CN1179414A) invented a catalyst composed of an organophosphorus compound containing a trivalent or pentavalent phosphorus atom and at least one carbon-phosphorus bond or a mixture of an organophosphorus compound and a compound containing a halogen atom, which is effectively used for decarbonylation reaction, that is, effectively releasing CO from a compound containing a -CO-CO-O- part in its molecular structure.

[0004] Liangfeng Chen of Shanghai Research Institute of Sinopec (CN110857272A) et al. invented a material prepared from polystyrene resin and quaternary phosphonium salt for decarbonylating oxalate to prepare carbonate. When preparing this type of catalyst, organic reagents such as acetonitrile, benzonitrile, toluene, and xylene need to be used. These solvents are poisonous to the environment and the human body, do not meet the requirements of green chemical development, and limit its industrial application to a certain extent.

[0005] Wei Zhang et al. disclosed a catalytic system for directly generating dimethyl carbonate by decarbonylation of dimethyl oxalate in CN113181894A. The preparation method of the catalyst is to disperse the catalyst components in a surfactant solvent to obtain a dispersion liquid, then immerse the carrier in the dispersion liquid, dry it, and calcine it at 700 - 1000 °C for 2 - 5 h to obtain the catalyst. However, this invention has the disadvantages of cumbersome preparation process, low selectivity of the target product, and high cost of using MOF as the carrier. At the same time, this process dissolves dimethyl oxalate in a solvent for decarbonylation reaction, increasing the subsequent separation cost.

[0006] Xu Jie et al. disclosed a heterogeneous catalyst for the transesterification reaction of cyclic carbonates with alcohols to synthesize linear carbonates and its preparation method in CN106076387A. This catalyst uses graphitic carbon nitride as the carrier and MgO or BaO obtained by the decomposition of alkaline earth metal nitrates (Mg(NO3)2 or Ba(NO3)2) as the active component. However, when using this catalyst, the conversion rate of cyclic carbonates and the yield of linear carbonates are relatively low.

[0007] Zhang Haoyang of Shanghai Normal University (Master's thesis in 2016, Research on the Decarbonylation of Dimethyl Oxalate to Dimethyl Carbonate Using Solid Base Catalysts) prepared a series of carbon-based catalysts using alkali metal carbonates as the active component and activated carbon as the carrier by the incipient wetness impregnation method. The activity of 5% Rb2CO3 / carbon CMK-3 is relatively good, and 98% of DMO can be decarbonylated to obtain DMC. However, the conversion rate of this catalyst decreased significantly after being reused four times.

[0008] Ma Xinbin et al. of Tianjin University (Chemical Reagents, 2004, 26(4): 197-200) studied the reaction of Zn(OAc)2·2H2O catalyzing the decarbonylation of diphenyl oxalate (DPO) to synthesize diphenyl carbonate (DPC), investigated process parameters such as reaction temperature and reaction time, and established that the optimal reaction conditions are a reaction temperature of 260 °C, a reaction time of 3 h, and a mass ratio of DPO to the catalyst of 100:1.5. The yield of DPC and the conversion rate of DPO reached the maximum values of 18.9% and 40.5% respectively.

[0009] Traditional activated carbon (AC)-supported catalysts are increasingly difficult to meet the requirements of modern industrial production due to the following disadvantages: First, the microporous structure of activated carbon greatly limits the mass transfer of substrate molecules during the reaction; second, the micropores smaller than 2 nm greatly limit the attachment sites of active metals, resulting in a large amount of metal outside the pores of the catalyst, and further leading to the loss and aggregation of active metals during the reaction.

[0010] The development of nitrogen-modified porous carbon materials (CN) brings hope for solving the above problems. The introduction of nitrogen atoms will cause changes in the acid-base properties of the carbon skeleton and its surface, improve the electron transfer efficiency of the catalyst skeleton, enhance the interaction between metal nanoparticles and the carrier in the supported catalyst system, etc., making it widely used as a carrier for nanometals to prepare metal-nitrogen modified carbon composites in heterogeneous catalytic reactions. Summary of the Invention

[0011] At present, the catalysts for the decarbonylation of oxalate to prepare carbonate have the disadvantages of large pollution in the preparation process, low activity and easy deactivation of the catalyst. In view of the above-mentioned prior art situation, the inventors of the present invention have conducted extensive and in-depth research on the catalysts for the decarbonylation of dialkyl oxalate to prepare dialkyl carbonate, in order to find a catalyst for the decarbonylation of dialkyl oxalate to prepare dialkyl carbonate that can overcome the above-mentioned disadvantages of the prior art, and the catalyst has a high conversion rate of dialkyl oxalate and selectivity of dialkyl carbonate, as well as an extended service life of the catalyst and fast decarbonylation performance.

[0012] To achieve the above object, the present invention adopts the following technical solutions:

[0013] 1. A supported catalyst comprising two or more of an alkali metal, an alkaline earth metal and phosphorus, wherein the carrier is a nitrogen-modified carbon-based material, preferably an amorphous nitrogen-modified carbon-based material.

[0014] 2. The catalyst according to Scheme 1, wherein the specific surface area of the catalyst is ≥200 m 2 / g, preferably 300 - 800 m 2 / g, more preferably 400 - 700 m 2 / g, and / or the pore volume is 0.1 - 2.5 cm 3 / g, preferably 0.2 - 2.0 cm 3 / g, more preferably 0.4 - 1.5 cm 3 / g, and / or the pore diameter is 0.5 - 60 nm, preferably 1 - 30 nm, more preferably 1.2 - 10 nm, and / or the nitrogen content in the catalyst is 0.5 - 30 wt%, preferably 1 - 25 wt%, more preferably 2 - 20 wt%, and / or the total weight of the alkali metal, alkaline earth metal and / or phosphorus is 10 - 40 wt%, preferably 12 - 35 wt%, more preferably 15 - 30 wt%, in each case based on the total weight of the catalyst.

[0015] 3. The catalyst according to Scheme 1 or 2, wherein the weight ratio of the alkali metal: alkaline earth metal: phosphorus: nitrogen-modified carbon-based material is (0 - 1.5):(0 - 2.5):(0 - 0.1):(2.1 - 4.5), preferably (0.1 - 1):(0.01 - 2.4):(0 - 0.09):(2.2 - 4.0), more preferably (0.1 - 0.8):(0.01 - 2.2):(0 - 0.08):(2.3 - 2.8).

[0016] 4. A method for preparing the catalyst according to any one of Schemes 1 - 3, comprising the following steps:

[0017] (1): Mix two or more of an alkali metal source, an alkaline earth metal source and a quaternary phosphonium salt with water to obtain a slurry;

[0018] (2): Add the precursor of the nitrogen-modified carbon-based material to the slurry obtained in step (1), obtain a mixture under stirring, and then dry the mixture.

[0019] (3): Calcinate the sample obtained in step (2) to obtain a catalyst for the decarbonylation reaction.

[0020] 5. The method according to embodiment 4, wherein the alkali metal source is one or more of lithium carbonate, sodium carbonate, potassium carbonate, rubidium carbonate, cesium carbonate, potassium sulfate, sodium oleate, and potassium oleate.

[0021] 6. The method according to embodiment 4 or 5, wherein the alkaline earth metal source is one or more of calcium hydroxide, magnesium hydroxide, calcium oxide, strontium oxide, barium oxide, calcium carbonate, magnesium carbonate, strontium carbonate, magnesium nitrate, and calcium nitrate.

[0022] 7. The method according to any one of embodiments 4-6, wherein the quaternary phosphonium salt is benzyltriethylammonium chloride and tetrabutylammonium chloride

[0023] 8. The method according to any one of embodiments 4-7, wherein the precursor of the nitrogen-modified carbon-based material is one or more of chitosan, N-acetyl-D-glucose, glucosamine hydrochloride, D-glucosamine sulfate, D-glucosaminic acid, sodium glucosamine sulfate, melamine, melamine monoamide, and dicyandiamide.

[0024] 9. A method for preparing a dialkyl carbonate by decarbonylation of a dialkyl oxalate, comprising decarbonylating the dialkyl oxalate in the presence of the catalyst according to any one of embodiments 1-3 or the catalyst prepared by the method according to any one of embodiments 4-8 to obtain a dialkyl carbonate, wherein the alkyl group is a straight-chain or branched alkyl group having 1-6 carbon atoms, preferably a straight-chain or branched alkyl group having 1-4 carbon atoms, more preferably methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, 2-ethylbutyl, n-pentyl, isopentyl, 1-methylpentyl, 1,3-dimethylbutyl, n-hexyl, and most preferably methyl, ethyl, n-propyl, n-butyl, and n-pentyl.

[0025] 10. Use of the catalyst according to any one of Schemes 1-3 or the catalyst prepared by the method according to any one of Schemes 4-8 for the decarbonylation of dialkyl oxalate to prepare dialkyl carbonate, wherein the alkyl group is an alkyl group having 1-6 carbon atoms, preferably an alkyl group having 1-4 carbon atoms, more preferably methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, 2-ethylbutyl, n-pentyl, isopentyl, 1-methylpentyl, 1,3-dimethylbutyl, n-hexyl, and most preferably methyl, ethyl, n-propyl, n-butyl, n-pentyl.

[0026] Compared with the catalysts for the decarbonylation of dimethyl oxalate to prepare dimethyl carbonate reported currently, the catalyst provided by the present invention for the decarbonylation of dialkyl oxalate to prepare dialkyl carbonate has the following advantages:

[0027] (1) Embedding the composite active component in the nitrogen-modified carbon-based material by a one-step method enhances the interaction between the active component and the support in the sample system, accelerates the electron transfer efficiency of the active catalyst skeleton, is beneficial to carbonyl removal, and exhibits excellent catalytic activity;

[0028] (2) The material prepared by the present invention has a rich pore structure, expanding its application in the fields of catalysis or adsorption;

[0029] (3) The nitrogen-modified carbon-based material anchors the active component, effectively inhibits the loss of the active component during the reaction process, and prolongs the service life of the catalyst. Description of the Drawings

[0030] Figure 1 Shows the X-ray diffraction (XRD) pattern of the catalyst support in Example 1. Detailed Embodiments

[0031] According to one aspect of the present invention, the present invention provides a supported catalyst comprising two or more of an alkali metal, an alkaline earth metal, and phosphorus, wherein the support is a nitrogen-modified carbon-based material.

[0032] According to an embodiment of the present invention, the specific surface area of the catalyst is ≥200 m 2 / g, preferably 300-800 m 2 / g, more preferably 400-700 m 2 / g.

[0033] According to an embodiment of the present invention, the pore volume of the catalyst is 0.1-2.5 cm 3 / g, preferably 0.2-2.0 cm 3 / g, more preferably 0.4-1.5 cm 3 / g.

[0034] According to an embodiment of the present invention, the pore diameter of the catalyst is 0.5 - 60 nm, preferably 1 - 30 nm, more preferably 1.2 - 10 nm.

[0035] According to an embodiment of the present invention, the carrier in the catalyst is preferably an amorphous nitrogen-modified carbon-based material.

[0036] According to an embodiment of the present invention, the nitrogen content in the catalyst is 0.5 - 30 wt%, preferably 1 - 25 wt%, more preferably 2 - 20 wt%, based on the total weight of the catalyst.

[0037] According to an embodiment of the present invention, the total weight of alkali metal, alkaline earth metal and / or phosphorus in the catalyst is 10 - 40 wt%, preferably 12 - 35 wt%, more preferably 15 - 30 wt%, based on the total weight of the catalyst.

[0038] According to an embodiment of the present invention, the weight ratio of alkali metal: alkaline earth metal: phosphorus: nitrogen-modified carbon-based material in the catalyst is (0 - 1.5):(0 - 2.5):(0 - 0.1):(2.1 - 4.5), preferably (0.1 - 1):(0.01 - 2.4):(0 - 0.09):(2.2 - 4.0), more preferably (0.1 - 0.8):(0.01 - 2.2):(0 - 0.08):(2.3 - 2.8).

[0039] According to another aspect of the present invention, a method for preparing the catalyst of the present invention is provided, and the method includes the following steps:

[0040] (1): Mix two or more of an alkali metal source, an alkaline earth metal source and a quaternary phosphonium salt with water to obtain a slurry;

[0041] (2): Add a precursor of the nitrogen-modified carbon-based material to the slurry obtained in step (1), obtain a mixture under stirring, and then dry the mixture;

[0042] (3): Calcinate the sample obtained in step (2) to obtain a catalyst for decarbonylation reaction.

[0043] In step (1) of the method of the present invention, there is no particular limitation on the alkali metal source, and it can be selected according to actual needs. For example, the alkali metal source is one or more of lithium carbonate, sodium carbonate, potassium carbonate, rubidium carbonate, cesium carbonate, potassium sulfate, sodium oleate and potassium oleate.

[0044] In step (1) of the method of the present invention, there is no particular limitation on the alkaline earth metal source, and it can be selected according to actual needs. For example, the alkaline earth metal source is one or more of calcium hydroxide, magnesium hydroxide, calcium oxide, strontium oxide, barium oxide, calcium carbonate, magnesium carbonate, strontium carbonate, magnesium nitrate and calcium nitrate.

[0045] In step (1) of the method of the present invention, there is no particular limitation on the quaternary phosphonium salt, and it can be selected according to actual needs. For example, the quaternary phosphonium salt is tetraphenyl chloride benzyltriethyl chloride and tetrabutyl chloride one or more of them.

[0046] In step (1) of the method of the present invention, there is no particular limitation on the amount of water used, and it can be selected according to actual needs.

[0047] In step (1) of the method of the present invention, the mixing can be carried out under stirring. For example, it can be stirred at a temperature of 10 - 80°C, preferably 20 - 60°C, more preferably 25 - 40°C. There is no particular limitation on the stirring time, and it can be selected according to actual needs. For example, the stirring time can be 0.5 - 10 h, preferably 1 - 8 h, more preferably 1.5 - 6 h. There is no particular limitation on the stirring speed, and it can be selected according to actual needs. For example, the stirring speed can be 400 - 1000 rpm, preferably 500 - 900 rpm, more preferably 600 - 850 rpm.

[0048] In step (2) of the method of the present invention, there is no particular limitation on the precursor of the nitrogen-modified carbon-based material, and it can be selected according to actual needs. For example, the precursor of the nitrogen-modified carbon-based material is one or more of chitosan, N-acetyl-D-glucose, glucosamine hydrochloride, D-glucosamine sulfate, D-glucosamic acid, sodium glucosamine sulfate, melamine, melamine monoamide, and dicyandiamide.

[0049] In step (2) of the method of the present invention, there is no particular limitation on the stirring temperature, and it can be selected according to actual needs. For example, it is stirred at a temperature of 40 - 100°C, preferably 50 - 90°C, more preferably 60 - 85°C. There is no particular limitation on the stirring time, and it can be selected according to actual needs. For example, the stirring time can be 0.5 - 10 h, preferably 1 - 8 h, more preferably 1.5 - 6 h. There is no particular limitation on the stirring speed, and it can be selected according to actual needs. For example, the stirring speed can be 400 - 1000 rpm, preferably 500 - 900 rpm, more preferably 600 - 850 rpm.

[0050] In step (2) of the method of the present invention, there is no particular limitation on the drying temperature, and it can be selected according to actual needs. For example, the mixture is dried at 80 - 150°C, preferably 90 - 120°C, more preferably 95 - 110°C. There is no particular limitation on the drying time, and it can be selected according to actual needs. For example, the drying time can be 0.5 - 10 h, preferably 1 - 8 h, more preferably 1.5 - 6 h.

[0051] In step (3) of the method of the present invention, there is no particular limitation on the calcination temperature, which can be selected according to actual needs. For example, the sample obtained in step (2) is calcined at 300-900°C, preferably 320-750°C, more preferably 350-600°C. There is no particular limitation on the calcination time, which can be selected according to actual needs. For example, the calcination time can be 0.5-12 h, preferably 1-8 h, more preferably 1.5-6 h. The calcination can be carried out in an inert gas atmosphere, such as a gas atmosphere of nitrogen, argon, etc.

[0052] According to another aspect of the present invention, there is provided a method for preparing a dialkyl carbonate by decarbonylation of a dialkyl oxalate, which comprises decarbonylating a dialkyl oxalate in the presence of the catalyst of the present invention or the catalyst prepared according to the method of the present invention to obtain a dialkyl carbonate.

[0053] In the method for preparing a dialkyl carbonate of the present invention, the alkyl group is a straight-chain or branched alkyl group having 1-6 carbon atoms, preferably a straight-chain or branched alkyl group having 1-4 carbon atoms, more preferably methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, 2-ethylbutyl, n-pentyl, isopentyl, 1-methylpentyl, 1,3-dimethylbutyl, n-hexyl, and most preferably methyl, ethyl, n-propyl, n-butyl, n-pentyl. The dialkyl carbonate is preferably selected from dimethyl carbonate, diethyl carbonate, di-n-propyl carbonate, di-n-butyl carbonate, and di-n-pentyl carbonate.

[0054] According to the method for preparing a dialkyl carbonate of the present invention, preferably, the dialkyl oxalate raw material is a dialkyl oxalate and / or a dialkyl oxalate solution.

[0055] Preferably, the solvent in the dialkyl oxalate solution is selected from at least one of methanol, ethanol, and a dialkyl carbonate. Preferably, the dialkyl carbonate as the solvent is the same substance as the target product dialkyl carbonate.

[0056] In a preferred embodiment, the dialkyl carbonate is dimethyl carbonate.

[0057] In another preferred embodiment, the conditions for the decarbonylation reaction of the dialkyl carbonate include: the reaction temperature is 160-280°C, preferably 180-260°C, more preferably 200-240°C; and / or the reaction time is 0.5-12 h, preferably 1-8 h, more preferably 1.5-6 h; and / or the stirring speed is 600-1000 rpm, preferably 700-900 rpm, more preferably 750-850 rpm.

[0058] The method for preparing dialkyl carbonate of the present invention can be carried out in any reactor capable of achieving the above reaction conditions. For example, it can be carried out in a fixed-bed reactor, a fluidized-bed reactor or a slurry-bed reactor, and is preferably carried out in a slurry-bed reactor.

[0059] According to the last aspect of the present invention, there is provided the use of the catalyst of the present invention or the catalyst prepared by the method of the present invention for decarbonylating dialkyl oxalate to prepare dialkyl carbonate.

[0060] The present invention will be described below in conjunction with specific embodiments, but these embodiments are only used to illustrate the present invention and do not constitute a limitation on the scope of the present invention.

[0061] Examples

[0062] Materials:

[0063] Purchased from Sinopharm Chemical Reagent Co., Ltd. and used directly without purification.

[0064] Testing methods:

[0065] The specific surface area, pore volume and pore diameter were measured by an ASAP2460 instrument from Micromeritics.

[0066] The nitrogen content was measured by a FlashSmart elemental analyzer from Thermo Fisher Scientific.

[0067] The liquid-phase products were analyzed by a 456C gas chromatograph from Varian.

[0068] X-ray diffraction (XRD) analysis was carried out using Cu Kα radiation on an XRD-7000S produced by Shimadzu.

[0069] Example 1:

[0070] 1. Preparation of the catalyst:

[0071] Step 1: Weigh 0.5 g of Rb2CO3 and 1.5 g of CaCO3 respectively and mix them with 50.0 g of water, and stir at a temperature of 50 °C for 2 h to obtain a slurry;

[0072] Step 2: Add 2.5 g of dicyandiamide to the slurry obtained in Step 1, stir at a temperature of 80 °C for 3 h, and then keep the semi-finished product at 100 °C for 4 h;

[0073] Step 3: After calcining the semi-finished product obtained in Step 2 in a nitrogen atmosphere at 550 °C for 3 h, wait for it to cool to obtain the finished product, named Sample A.

[0074] The specific surface area of Sample A was obtained by BET detection as 610 m 2 / g, and the pore volume was 0.5 cm 3 / g, with a pore diameter of 1.5 nm, and its N content measured by an elemental analyzer is 20 wt%.

[0075] 2. Evaluation of the catalyst:

[0076] Sample A was placed in a slurry bed reactor for the decarbonylation of dimethyl oxalate to produce dimethyl carbonate. The reaction conditions were as follows: 100 g of dimethyl oxalate, a bed temperature of 220 °C, a catalyst sample addition of 1.0 g, a reaction time of 4 h, and a stirring speed of 800 rpm. After testing, the conversion rate of dimethyl oxalate on sample A was 98.6%, and the selectivity for dimethyl carbonate was 98.4%. Table 1 shows the reuse of this catalyst. As can be seen from this table, after 10 times of reuse, the yield of dimethyl carbonate can still be maintained at 83.4%.

[0077] Table 1: Number of reuse times of sample A in the decarbonylation of dimethyl oxalate to produce dimethyl carbonate

[0078] Conversion rate of dimethyl oxalate, % Selectivity of dimethyl carbonate, % Yield of dimethyl carbonate, % First reuse 98.6 98.4 97.0 Second reuse 97.6 98.2 95.8 Third reuse 96.8 97.8 94.7 Fourth reuse 94.9 96.9 92.0 Fifth reuse 95.1 97.2 92.4 Sixth reuse 94.4 95.1 89.8 Seventh reuse 93.8 94.8 88.9 Eighth reuse 93.1 91.3 85.0 Ninth reuse 91.6 92.8 85.0 Tenth reuse 90.5 92.1 83.4

[0079] Example 2:

[0080] 1. Preparation of the catalyst:

[0081] Step 1: Weigh 1.0 g of K2CO3 and 0.2 g of CaCO3 separately and mix them with 30.0 g of water. Stir at 40 °C for 2 h to obtain a slurry;

[0082] Step 2: Add 4.0 g of glucosamine hydrochloride to the slurry obtained in Step 1. Stir at 70 °C for 3 h, and then keep the semi-finished product at 100 °C for 4 h;

[0083] Step 3: After calcining the semi-finished product obtained in Step 2 in a nitrogen atmosphere at 450 °C for 4 h, wait for it to cool to obtain the finished product, named sample B.

[0084] The specific surface area of sample B obtained by BET detection is 532 m 2 / g, the pore volume is 0.62 cm 3 / g, the pore diameter is 2.1 nm, and its N content measured by an elemental analyzer is 9 wt%.

[0085] 2. Evaluation of the catalyst:

[0086] Sample B was placed in a slurry bed reactor for the decarbonylation of dimethyl oxalate to produce dimethyl carbonate. The reaction conditions were as follows: 100 g of dimethyl oxalate, a bed temperature of 220 °C, a catalyst sample addition of 1.0 g, a reaction time of 4 h, and a stirring speed of 800 rpm. After testing, the conversion rate of dimethyl oxalate on sample B was 94.1%, and the selectivity for dimethyl carbonate was 97.4%.

[0087] Example 3:

[0088] 1. Preparation of catalyst:

[0089] Step 1: Weigh 1.0 g of Rb2CO3 and 2.0 g of Mg(NO3)2 respectively, mix them with 20.0 g of water, and stir for 2 h at a temperature of 30 °C to obtain a slurry;

[0090] Step 2: Add 2.0 g of melamine to the slurry obtained in Step 1, stir at a temperature of 80 °C for 3 h, and then keep the semi-finished product at 100 °C for 4 h;

[0091] Step 3: After calcining the semi-finished product obtained in Step 2 in a nitrogen atmosphere at 550 °C for 5 h, and waiting for cooling, the finished product is obtained and named Sample C.

[0092] The specific surface area of Sample C obtained by BET detection is 460 m 2 / g, the pore volume is 0.81 cm 3 / g, the pore diameter is 3.6 nm, and the N content measured by an elemental analyzer is 17 wt%.

[0093] 2. Evaluation of catalyst:

[0094] Place Sample C in a slurry bed reactor for the reaction of decarbonylation of dimethyl oxalate to prepare dimethyl carbonate. The reaction conditions are as follows: 100 g of dimethyl oxalate, the bed temperature is 220 °C, the addition amount of the catalyst sample is 1.0 g, the reaction time is 4 h, and the stirring speed is 800 rpm. After testing, the conversion rate of dimethyl oxalate on Sample C is 97.7%, and the selectivity of dimethyl carbonate is 98.1%.

[0095] Example 4:

[0096] 1. Preparation of catalyst:

[0097] Step 1: Weigh 1.0 g of tetraphenyl chloride and 2.5 g of CaO, mix them with 40.0 g of water, and stir for 2 h at a temperature of 30 °C to obtain a slurry;

[0098] Step 2: Add 5.0 g of glucosamine hydrochloride to the slurry obtained in Step 1, stir at a temperature of 80 °C for 3 h, and then keep the semi-finished product at 100 °C for 4 h;

[0099] Step 3: After calcining the semi-finished product obtained in Step 2 in a nitrogen atmosphere at 350 °C for 6 h, and waiting for cooling, the finished product is obtained and named Sample D.

[0100] The specific surface area of Sample D obtained by BET detection is 480 m 2 / g, the pore volume is 0.73 cm 3 / g, with a pore size of 1.2 nm, and the N content measured by an elemental analyzer is 2 wt%.

[0101] 2. Evaluation of the catalyst:

[0102] Sample D was placed in a slurry bed reactor for the decarbonylation of dimethyl oxalate to prepare dimethyl carbonate. The reaction conditions were as follows: 100 g of dimethyl oxalate, a bed temperature of 220 °C, a catalyst sample addition of 1.0 g, a reaction time of 4 h, and a stirring speed of 800 rpm. After testing, the conversion rate of dimethyl oxalate on sample D was 94.6%, and the selectivity for dimethyl carbonate was 96.2%.

[0103] Example 5:

[0104] 1. Preparation of the catalyst:

[0105] Step 1: Weigh 1.4 g of lithium carbonate and 2.5 g of BaO and mix them with 40.0 g of water, stir at 30 °C for 2 h to obtain a slurry;

[0106] Step 2: Add 7.0 g of glucosamine hydrochloride to the slurry obtained in Step 1, stir at 80 °C for 3 h, and then keep the semi-finished product at 100 °C for 4 h;

[0107] Step 3: After calcining the semi-finished product obtained in Step 2 in a nitrogen atmosphere at 460 °C for 3 h, cool it to obtain the finished product, named sample E.

[0108] The specific surface area of sample E was obtained by BET detection as 534 m 2 / g, the pore volume was 0.72 cm 3 / g, the pore size was 1.9 nm, and the N content measured by an elemental analyzer was 6.8 wt%.

[0109] 2. Evaluation of the catalyst:

[0110] Sample E was placed in a slurry bed reactor for the decarbonylation of dimethyl oxalate to prepare dimethyl carbonate. The reaction conditions were as follows: 100 g of dimethyl oxalate, a bed temperature of 220 °C, a catalyst sample addition of 1.0 g, a reaction time of 4 h, and a stirring speed of 800 rpm. After testing, the conversion rate of dimethyl oxalate on sample E was 96.6%, and the selectivity for dimethyl carbonate was 95.4%.

[0111] Example 6:

[0112] 1. Preparation of the catalyst:

[0113] Step 1: Weigh 1.4 g of rubidium carbonate and 2.5 g of BaO and mix them with 40.0 g of water, stir at 30 °C for 2 h to obtain a slurry;

[0114] Step 2: Add 10.0 g of N-acetyl-D-glucose to the slurry obtained in Step 1, stir at 80 °C for 3 h, and then keep the semi-finished product at 100 °C for 4 h;

[0115] Step 3: After calcining the semi-finished product obtained in Step 2 in a nitrogen atmosphere at 500 °C for 5 h, cool it to obtain the finished product, named Sample F.

[0116] The specific surface area of Sample F obtained by BET detection is 454 m 2 / g, the pore volume is 0.9 cm 3 / g, the pore diameter is 3.8 nm, and the N content measured by an elemental analyzer is 7 wt%.

[0117] 2. Evaluation of the catalyst:

[0118] Place Sample F in a slurry bed reactor for the reaction of decarbonylation of dimethyl oxalate to prepare dimethyl carbonate. The reaction conditions are as follows: 100 g of dimethyl oxalate, the bed temperature is 220 °C, the addition amount of the catalyst sample is 1.0 g, the reaction time is 4 h, and the stirring speed is 800 rpm. After testing, the conversion rate of dimethyl oxalate on Sample F is 98.6%, and the selectivity of dimethyl carbonate is 96.4%.

[0119] Example 7:

[0120] 1. Preparation of the catalyst:

[0121] Step 1: Weigh 2.4 g of potassium oleate and 2.5 g of CaO and mix them with 40.0 g of water, stir at 30 °C for 2 h to obtain a slurry;

[0122] Step 2: Add 10.0 g of N-acetyl-D-glucose to the slurry obtained in Step 1, stir at 80 °C for 3 h, and then keep the semi-finished product at 100 °C for 4 h;

[0123] Step 3: After calcining the semi-finished product obtained in Step 2 in a nitrogen atmosphere at 500 °C for 5 h, cool it to obtain the finished product, named Sample G.

[0124] The specific surface area of Sample G obtained by BET detection is 487 m 2 / g, the pore volume is 0.67 cm 3 / g, the pore diameter is 1.5 nm, and the N content measured by an elemental analyzer is 5.8 wt%.

[0125] 2. Evaluation of the catalyst:

[0126] Sample G was placed in a slurry bed reactor for the decarbonylation of dimethyl oxalate to prepare dimethyl carbonate. The reaction conditions were as follows: 100 g of dimethyl oxalate, a bed temperature of 220 °C, a catalyst sample addition of 1.0 g, a reaction time of 4 h, and a stirring speed of 800 rpm. After testing, the conversion rate of dimethyl oxalate on sample G was 94.3%, and the selectivity of dimethyl carbonate was 93.4%.

[0127] Example 8:

[0128] 1. Preparation of the catalyst:

[0129] Step 1: Weigh 0.5 g of cesium carbonate and 1.0 g of BaO respectively, mix them with 80.0 g of water, and stir at 30 °C for 2 h to obtain a slurry;

[0130] Step 2: Add 3.0 g of melamine monoamide to the slurry obtained in Step 1, stir at 80 °C for 3 h, and then keep the semi-finished product at 100 °C for 4 h;

[0131] Step 3: After calcining the semi-finished product obtained in Step 2 in a nitrogen atmosphere at 550 °C for 4 h, and waiting for it to cool, the finished product was obtained and named sample H.

[0132] The specific surface area of sample H was obtained by BET detection as 567 m 2 / g, the pore volume was 0.78 cm 3 / g, the pore diameter was 1.8 nm, and the N content measured by an elemental analyzer was 7.5 wt%.

[0133] 2. Evaluation of the catalyst:

[0134] Sample H was placed in a slurry bed reactor for the decarbonylation of dimethyl oxalate to prepare dimethyl carbonate. The reaction conditions were as follows: 100 g of dimethyl oxalate, a bed temperature of 220 °C, a catalyst sample addition of 1.0 g, a reaction time of 4 h, and a stirring speed of 800 rpm. After testing, the conversion rate of dimethyl oxalate on sample H was 95.5%, and the selectivity of dimethyl carbonate was 94.2%.

[0135] Example 9:

[0136] 1. Preparation of the catalyst:

[0137] Sample A was prepared according to the method of Example 1.

[0138] 2. Evaluation of the catalyst:

[0139] Sample A was placed in a slurry bed reactor for the decarbonylation of diethyl oxalate to prepare diethyl carbonate. The reaction conditions were as follows: 100 g of diethyl oxalate, a bed temperature of 220 °C, a catalyst sample addition of 1.0 g, a reaction time of 4 h, and a stirring speed of 800 rpm. After testing, the conversion rate of diethyl oxalate on this sample was 97.8%, and the selectivity of diethyl carbonate was 98.2%.

[0140] Example 10:

[0141] 1. Preparation of the catalyst:

[0142] Sample A was prepared according to the method of Example 1.

[0143] 2. Evaluation of the catalyst:

[0144] Sample A was placed in a slurry bed reactor for the decarbonylation of di-n-propyl oxalate to prepare di-n-propyl carbonate. The reaction conditions were as follows: 100 g of di-n-propyl oxalate, a bed temperature of 220 °C, a catalyst sample addition of 1.0 g, a reaction time of 4 h, and a stirring speed of 800 rpm. After testing, the conversion rate of di-n-propyl oxalate on this sample was 98.6%, and the selectivity of di-n-propyl carbonate was 97.8%.

[0145] Example 11:

[0146] 1. Preparation of the catalyst:

[0147] Sample A was prepared according to the method of Example 1.

[0148] 2. Evaluation of the catalyst:

[0149] Sample A was placed in a slurry bed reactor for the decarbonylation of di-n-butyl oxalate to prepare di-n-butyl carbonate. The reaction conditions were as follows: 100 g of di-n-butyl oxalate, a bed temperature of 220 °C, a catalyst sample addition of 1.0 g, a reaction time of 4 h, and a stirring speed of 800 rpm. After testing, the conversion rate of di-n-butyl oxalate on this sample was 96.9%, and the selectivity of di-n-butyl carbonate was 96.9%.

[0150] Comparative Example 1:

[0151] 1. Preparation of the catalyst:

[0152] According to the method disclosed in CN106076387A, a MgO / g-C3N4 catalyst was prepared. The specific process was to mix 20 parts by mass of Mg(NO3)2 and 40 parts by mass of dicyandiamide in ethanol, and then heat it in an open container until the solid was dry. The above solid was placed in a muffle furnace and calcined in a closed crucible at 550 °C to obtain the catalyst.

[0153] 2. Evaluation of the catalyst:

[0154] The prepared catalyst was placed in a slurry bed reactor for the decarbonylation of dimethyl oxalate to produce dimethyl carbonate. The reaction conditions were as follows: 100 g of dimethyl oxalate, a bed temperature of 220 °C, an addition amount of 1.0 g of the catalyst sample, a reaction time of 4 h, and a stirring speed of 800 rpm. The product was analyzed by gas chromatography. The conversion rate of dimethyl oxalate in this sample was 52.8%, and the selectivity for dimethyl carbonate was 92.8%.

[0155] Comparative Example 2:

[0156] 1. Preparation of the catalyst:

[0157] Using the preparation steps as described in Example 3, the difference was that only Mg(NO3)2 was used instead of Rb2CO3 and Mg(NO3)2 to prepare a single-component MgO-supported nitrogen-modified carbon material.

[0158] 2. Evaluation of the catalyst:

[0159] The prepared catalyst was placed in a slurry bed reactor for the decarbonylation of dimethyl oxalate to produce dimethyl carbonate. The reaction conditions were as follows: 100 g of dimethyl oxalate, a bed temperature of 220 °C, an addition amount of 1.0 g of the catalyst sample, a reaction time of 4 h, and a stirring speed of 800 rpm. The product was analyzed by gas chromatography. The conversion rate of dimethyl oxalate in this sample was 62.6%, and the selectivity for dimethyl carbonate was 93.4%.

[0160] Comparative Example 3:

[0161] 1. Preparation of the catalyst:

[0162] To compare the catalytic performance of the samples prepared by the impregnation method and the samples prepared in the present invention in the decarbonylation of dimethyl oxalate to produce dimethyl carbonate, a comparative sample 3 was prepared by the impregnation method, and the lifetime of comparative sample 3 in the decarbonylation of dimethyl oxalate to produce dimethyl carbonate was investigated.

[0163] Comparative sample 3 was prepared according to the sample ratio similar to that in Example 1. The specific process was as follows:

[0164] Weigh 0.5 g of Rb2CO3, 1.5 g of CaCO3, and 2.5 g of activated carbon and mix them with 50.0 g of water. Stir at a temperature of 30 °C for 2 h to obtain a slurry. Let it stand overnight, and then keep it at 100 °C for 4 h. The obtained semi-finished product was calcined in a nitrogen atmosphere at 550 °C for 3 h, and after cooling, the finished product was obtained and named comparative sample 3.

[0165] 2. Evaluation of the catalyst:

[0166] The comparative sample 3 was placed in a slurry bed reactor for the decarbonylation of dimethyl oxalate to produce dimethyl carbonate. The reaction conditions were as follows: 100 g of dimethyl oxalate, a bed temperature of 220 °C, an addition amount of 1.0 g of the catalyst sample, a reaction time of 4 h, and a stirring speed of 800 rpm. Table 2 shows the reuse of the catalyst of comparative sample 3.

[0167] Table 2: Service life of comparative sample 3 in the decarbonylation of dimethyl oxalate to produce dimethyl carbonate

[0168] Conversion rate of dimethyl oxalate, % Selectivity of dimethyl carbonate, % Yield of dimethyl carbonate, % First reuse 91.5 95.0 86.9 Second reuse 84.3 91.8 77.4 Third reuse 80.9 78.9 63.8

[0169] Comparative Example 4:

[0170] 1. Preparation of the catalyst:

[0171] To further verify the effect of the present invention, according to the preparation scheme disclosed by Zhang Haoyang of Shanghai Normal University (Master's thesis in 2016, Research on solid base catalysts for the decarbonylation of dimethyl oxalate to produce dimethyl carbonate), the comparative sample 4 Rb2CO3 / carbon CMK-3 was prepared.

[0172] 2. Evaluation of the catalyst:

[0173] The prepared sample was placed in a slurry bed reactor for the decarbonylation of dimethyl oxalate to produce dimethyl carbonate. The reaction conditions were as follows: 100 g of dimethyl oxalate, a bed temperature of 220 °C, an addition amount of 1.0 g of the catalyst sample, a reaction time of 4 h, and a stirring speed of 800 rpm. Table 3 shows the reuse of the catalyst of comparative sample 4.

[0174] Table 3: Service life of comparative sample 4 in the decarbonylation of dimethyl oxalate to produce dimethyl carbonate

[0175] Conversion rate of dimethyl oxalate, % Selectivity of dimethyl carbonate, % Yield of dimethyl carbonate, % First reuse 93.0 94.1 87.5 Second reuse 90.1 93.0 83.8 Third reuse 82.1 93.4 76.7

[0176] Comparative Example 5:

[0177] 1. Preparation of the catalyst:

[0178] To further test the effect of the present invention, according to the preparation scheme disclosed in CN113181894A, the comparative sample 5 Rb-Ca / C was prepared. The specific process was to dissolve 0.5 g of Rb2CO3, 1.5 g of CaCO3, and 2 g of CTAB in 500 mL of deionized water / ethanol (volume ratio 5:1) and stir, and then soak and adsorb tetraethyl orthogermanate on activated carbon with a specific surface area of 500 m 2 / g for 3 h. After taking it out, it was pyrolyzed at high temperature under argon to obtain activated carbon coated with a germanium dioxide layer. 5 g of the above-mentioned activated carbon coated with a germanium dioxide layer was dispersed in the Rb-Ca slurry. After drying, the obtained solid was calcined at 800 °C for 3 h to prepare the Rb-Ca / C catalyst.

[0179] 2. Evaluation of the catalyst:

[0180] The prepared sample was placed in a slurry bed reactor for the decarbonylation reaction of dimethyl oxalate to prepare dimethyl carbonate. The reaction conditions were as follows: 100 g of dimethyl oxalate, a bed temperature of 220 °C, an addition amount of 1.0 g of the catalyst sample, a reaction time of 4 h, and a stirring speed of 800 rpm. Table 4 shows the reuse situation of the catalyst of Comparative Sample 5.

[0181] Table 4: Service life of Comparative Sample 5 in the decarbonylation of dimethyl oxalate to prepare dimethyl carbonate

[0182] Conversion rate of dimethyl oxalate, % Selectivity of dimethyl carbonate, % Yield of dimethyl carbonate, % First reuse 85.1 91.2 77.6 Second reuse 72.8 90.6 65.9

[0183] By comparing with the data of the comparative samples in the comparative examples, it can be seen that the samples of the examples of the present invention have better decarbonylation performance and stability.

Claims

1. A supported catalyst for the decarbonylation of dialkyl oxalate to prepare dialkyl carbonate, comprising two or more of alkali metals, alkaline earth metals and phosphorus, wherein the carrier is a nitrogen-modified carbon-based material, and the specific surface area of the catalyst is ≥200 m 2 / g, wherein the weight ratio of the alkali metal: alkaline earth metal: phosphorus: nitrogen-modified carbon-based material is (0 - 1.5):(0 - 2.5):(0 - 0.1):(2.1 - 4.5), wherein the source of the alkali metal is one or more of lithium carbonate, sodium carbonate, potassium carbonate, rubidium carbonate, cesium carbonate, potassium sulfate, sodium oleate and potassium oleate, and wherein the source of the alkaline earth metal is one or more of calcium hydroxide, magnesium hydroxide, calcium oxide, strontium oxide, barium oxide, calcium carbonate, magnesium carbonate, strontium carbonate, magnesium nitrate and calcium nitrate.

2. The catalyst according to claim 1, wherein the carrier is an amorphous nitrogen-modified carbon-based material.

3. The catalyst according to claim 1, wherein the pore volume is 0.1 - 2.5 cm 3 / g, and / or the pore diameter is 0.5 - 60 nm, and / or the nitrogen content in the catalyst is 0.5 - 30 wt%, and / or the total weight of alkali metal, alkaline earth metal and / or phosphorus is 10 - 40 wt%, in each case based on the total weight of the catalyst.

4. The catalyst according to claim 1, wherein the specific surface area of the catalyst is 300 - 800 m 2 / g, and / or the pore volume is 0.2 - 2.0 cm 3 / g, and / or the pore diameter is 1 - 30 nm, and / or the nitrogen content in the catalyst is 1 - 25% by weight, and / or the sum of the weights of alkali metals, alkaline earth metals and / or phosphorus is 12 - 35% by weight, in each case based on the total weight of the catalyst.

5. The catalyst according to claim 1, wherein the specific surface area of the catalyst is 400 - 700 m 2 / g, and / or the pore volume is 0.4 - 1.5 cm 3 / g, and / or the pore diameter is 1.2 - 10 nm, and / or the nitrogen content in the catalyst is 2 - 20% by weight, and / or the total weight of alkali metal, alkaline earth metal and / or phosphorus is 15 - 30% by weight, in each case based on the total weight of the catalyst.

6. The catalyst according to any one of claims 1-5, wherein the weight ratio of the alkali metal: alkaline earth metal: phosphorus: nitrogen-modified carbon-based material is (0.1-1):(0.01-2.4):(0-0.09):(2.2-4.0).

7. The catalyst according to any one of claims 1-5, wherein the weight ratio of the alkali metal: alkaline earth metal: phosphorus: nitrogen-modified carbon-based material is (0.1-0.8):(0.01-2.2):(0-0.08):(2.3-2.8).

8. A method for preparing the catalyst according to any one of claims 1-7, comprising the following steps: (1): Mix two or more of an alkali metal source, an alkaline earth metal source, and a quaternary phosphonium salt with water to obtain a slurry; (2): Add a precursor of the nitrogen-modified carbon-based material to the slurry obtained in step (1), obtain a mixture under stirring, and then dry the mixture; (3): Calcinate the sample obtained in step (2) to obtain a catalyst for decarbonylation reaction.

9. The method according to claim 8, wherein the alkali metal source is one or more of lithium carbonate, sodium carbonate, potassium carbonate, rubidium carbonate, cesium carbonate, potassium sulfate, sodium oleate, and potassium oleate.

10. The method according to claim 8, wherein the alkaline earth metal source is one or more of calcium hydroxide, magnesium hydroxide, calcium oxide, strontium oxide, barium oxide, calcium carbonate, magnesium carbonate, strontium carbonate, magnesium nitrate, and calcium nitrate.

11. The method according to claim 9, wherein the alkaline earth metal source is one or more of calcium hydroxide, magnesium hydroxide, calcium oxide, strontium oxide, barium oxide, calcium carbonate, magnesium carbonate, strontium carbonate, magnesium nitrate, and calcium nitrate.

12. The method according to any one of claims 8-11, wherein the quaternary phosphonium salt is tetraphenyl chloride , benzyltriethyl chloride and tetrabutyl chloride or one or more of them.

13. The method according to any one of claims 8-11, wherein the precursor of the nitrogen-modified carbon-based material is one or more of chitosan, N-acetyl-D-glucose, glucosamine hydrochloride, D-glucosamine sulfate, D-glucosaminic acid, sodium glucosamine sulfate, melamine, melamine monoamide, and dicyandiamide.

14. The method according to claim 12, wherein the precursor of the nitrogen-modified carbon-based material is one or more of chitosan, N-acetyl-D-glucose, glucosamine hydrochloride, D-glucosamine sulfate, D-glucosaminic acid, sodium glucosamine sulfate, melamine, melamine monoamide, and dicyandiamide.

15. A method for preparing a dialkyl carbonate by decarbonylation of a dialkyl oxalate, comprising decarbonylating an alkyl oxalate in the presence of the catalyst according to any one of claims 1-7 or the catalyst prepared by the method according to any one of claims 8-14 to obtain an alkyl carbonate, wherein the alkyl is an alkyl having 1-6 carbon atoms.

16. The method according to claim 15, wherein the alkyl is an alkyl having 1-4 carbon atoms.

17. The method according to claim 15, wherein the alkyl group is methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, 2-ethylbutyl, n-pentyl, isopentyl, 1-methylpentyl, 1,3-dimethylbutyl, n-hexyl.

18. The method according to claim 15, wherein the alkyl group is methyl, ethyl, n-propyl, n-butyl, n-pentyl.

19. Use of the catalyst according to any one of claims 1-7 or the catalyst prepared by the method according to any one of claims 8-14 for decarbonylation of dialkyl oxalate to prepare dialkyl carbonate, wherein the alkyl group is an alkyl group having 1-6 carbon atoms.

20. The use according to claim 19, wherein the alkyl group has 1-4 carbon atoms.

21. The use according to claim 19, wherein the alkyl group is methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, 2-ethylbutyl, n-pentyl, isopentyl, 1-methylpentyl, 1,3-dimethylbutyl, n-hexyl.

22. The use according to claim 19, wherein the alkyl group is methyl, ethyl, n-propyl, n-butyl, n-pentyl.

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