Solid-phase supported catalyst for preparing dimethyl carbonate as well as preparation method and application of solid-phase supported catalyst

Abstract

The invention provides a solid-phase supported catalyst for preparing dimethyl carbonate as well as a preparation method and application of the solid-phase supported catalyst, and belongs to the technical field of catalyst preparation. The solid-phase supported catalyst comprises an active component and a carrier, the active component is cuprous chloride, the carrier is hydroxyapatite, the mass ratio of the cuprous chloride to the hydroxyapatite is 1: 5-1: 8, the solid-phase supported catalyst provided by the invention can be used for preparing the dimethyl carbonate, the dosage of the cuprous chloride active component in the solid-phase supported catalyst is small, and the solid-phase supported catalyst can be used for preparing the dimethyl carbonate. The solid-phase supported catalyst has the advantages that the solid-phase supported catalyst prepared by the method is favorable for reducing the loss of Cl in catalytic reaction and the corrosion to equipment, the high methanol conversion rate of 12-15% and the high DMC selectivity of 95-99% are obtained in the preparation of dimethyl carbonate, and the solid-phase supported catalyst can be recycled.

Description

Technical Field

[0001] The invention relates to the technical field of catalyst preparation, and in particular to a solid-phase supported catalyst for preparing dimethyl carbonate and a preparation method and application thereof. Background Art

[0002] Dimethyl carbonate (DMC), with a chemical formula of CH3O-CO-CH3O, is an important environmentally friendly green organic chemical raw material. Due to the presence of methyl, carbonyl, methoxy and other groups in its structure, it can replace phosgene as a carbonylating agent, dimethyl sulfate as a methylating agent, and methyl tert-butyl ether as an environmentally friendly gasoline additive. On the other hand, using dimethyl carbonate as a raw material, a variety of high value-added fine specialty chemicals can be developed and prepared, which are widely used in the fields of medicine, pesticides, synthetic materials, dyes, lubricant additives, food flavoring agents, electronic chemicals, etc. At the same time, when the oxygen content of DMC is as high as 53.3%, it can be used as an environmentally friendly automotive gasoline additive, which is superior to the currently used methyl tert-butyl ether (MTBE) in terms of increasing octane number and reducing emissions; DMC can also be used as a raw material for high-energy battery electrolyte and ester exchange to prepare diphenyl carbonate (DPC). Especially after the Italian company EniChem developed a new non-phosgene process for synthesizing polycarbonate (PC) from diphenyl carbonate and bisphenol A, the research and development of DMC has attracted much attention.

[0003] At present, the industrial synthesis of dimethyl carbonate mainly includes phosgene method, methanol oxidation carbonylation method, ester exchange method, methanol urea method, etc. Compared with other DMC synthesis processes such as phosgene method and ester exchange method, methanol oxidation carbonylation method uses methanol, carbon monoxide and oxygen as raw materials to synthesize DMC, which is less toxic, the raw materials are cheap and easy to obtain, and theoretically only the by-product water is generated, which has little pollution to the environment, and the atomic utilization rate is high, which is thermodynamically favorable. Its reaction formula is as follows:

[0004] 2CH3OH+CO+1 / 2O2→C3H6O3+H2O

[0005] According to the different reactors used in the reaction process, the oxidative carbonylation method can be divided into two types: liquid phase synthesis method and gas phase synthesis method, and its catalyst types can be divided into cobalt, palladium and copper. Copper catalysts are inexpensive and show excellent activity in reactions involving CO, becoming the research focus of scholars, especially cuprous catalysts, which are catalysts with good activity and selectivity. Therefore, the development of cuprous catalysts has become the development focus of this preparation method.

[0006] Hydroxyapatite (HAP) is a weakly alkaline calcium phosphate salt that is slightly soluble in water. It belongs to the hexagonal crystal system and has a hexagonal structure. The plane perpendicular to the c-axis is a hexagon. The angle between the a-axis and the b-axis is 120°. The lattice parameters are a=b=0.9421nm, c=0.6882nm. Hydroxyapatite is a multi-purpose inorganic material that is resistant to high temperatures, alkalis and water and insoluble. It can be used in biomedicine, adsorption, catalysis, fluorescence, lasers and semiconductors. Hydroxyapatite has solid alkalinity, strong ion exchange capacity and large specific surface area, which makes it have broad application prospects in the field of catalysis. Zhang Dinglin, Zhao Huawen, Zhao Xianying, et al. Application of hydroxyapatite as catalyst and catalyst carrier [J]. Progress in Chemistry, 2011, 23(004): 687-694 reported the application of hydroxyapatite as catalyst and catalyst carrier.

[0007] However, there are few reports on the use of hydroxyapatite (HAp) as a catalyst for the oxidative carbonylation of methanol to produce dimethyl carbonate. Existing studies have explored the use of hydroxyapatite as a catalyst carrier in the liquid phase oxidative carbonylation of methanol to produce dimethyl carbonate. This study used a hydrothermal method to prepare hydroxyapatite (HAp). Then, CaCl2 and HAp were mixed evenly in different molar ratios to obtain chloroapatite (ClAp). ClAp was mixed with CuCl2, stirred evenly, and reacted at a constant temperature to obtain Cu(Ⅱ)ClAp. A certain volume of sodium hydroxide solution and hydrazine hydrate solution were added to the reaction solution, washed, centrifuged, vacuum dried, and ground into powder to obtain Cu(Ⅰ)ClAp catalyst. The preparation of such catalysts is complicated, too many chemicals are introduced, and the process is difficult to control. In the test of preparing dimethyl carbonate by liquid phase oxidative carbonylation of methanol, the DMC selectivity obtained under the optimal conditions for catalyst preparation was 98.66%, but the methanol conversion rate was only 5.09%, and the amount of catalyst relative to methanol was not mentioned. Therefore, it is urgent to develop a catalyst with a simple and controllable preparation process and better catalytic performance, which is supported by hydroxyapatite and used for preparing dimethyl carbonate by liquid phase oxidative carbonylation of methanol. Summary of the invention

[0008] In view of the deficiencies in the prior art, the present invention provides a solid-phase supported catalyst for preparing dimethyl carbonate and a preparation method and application thereof.

[0009] In order to achieve the above technical objectives, on the one hand, the present invention provides a solid-phase supported catalyst for preparing dimethyl carbonate, wherein the solid-phase supported catalyst comprises an active component and a carrier, wherein the active component is cuprous chloride, the carrier is hydroxyapatite, and the mass ratio of cuprous chloride to hydroxyapatite is 1:(5-8).

[0010] Exemplarily, the mass ratio of cuprous chloride to hydroxyapatite is 1:5, and the relevant mass ratio relationship is given in the embodiment of the present invention.

[0011] Exemplarily, the mass ratio of cuprous chloride to hydroxyapatite is 1:6, and the relevant mass ratio relationship is given in the embodiment of the present invention.

[0012] Exemplarily, the mass ratio of cuprous chloride to hydroxyapatite is 1:7, and the relevant mass ratio relationship is given in the embodiment of the present invention.

[0013] Exemplarily, the mass ratio of cuprous chloride to hydroxyapatite is 1:8, and the relevant mass ratio relationship is given in the embodiment of the present invention.

[0014] The cuprous chloride in the solid phase supported catalyst provided by the present invention is an active component with the advantages of high catalytic activity, good catalyst selectivity and high catalyst stability. As an active component, cuprous chloride can significantly improve the efficiency of the catalytic reaction in the solid phase supported catalyst, thereby accelerating the reaction process and improving production efficiency; the molecular structure and chemical properties of cuprous chloride make it have good selectivity in different chemical reactions, and this selectivity helps to control the type and proportion of the reaction products and improve the yield and purity of the target compound; cuprous chloride shows high stability in the catalytic reaction and is not easy to decompose or deteriorate. This stability ensures that the catalytic performance of the catalyst can remain relatively stable during long-term use.

[0015] The hydroxyapatite in the solid phase supported catalyst provided by the present invention has the following advantages as a catalyst carrier: (1) it has strong ion exchangeability. Hydroxyapatite can exchange ions with most metal ions. Based on this property, a highly dispersed and stable supported metal catalyst can be prepared; (2) the surface acid-base adjustability. In the process of preparing hydroxyapatite, the acidity and alkalinity of the hydroxyapatite surface can be adjusted by adjusting the calcium-phosphorus ratio to meet the needs of different catalytic reactions; (3) the surface of hydroxyapatite has abundant hydroxyl groups and strong adsorption. It can be modified by organic compounds containing polar functional groups, so it can better load organic metal compounds with polar functional groups. Hydroxyapatite is widely used as a catalyst or catalyst carrier in oxidation reactions, reduction reactions, and CC bond formation reactions.

[0016] The adsorption and distribution of active components on the carrier can be carried out by adsorbing the carrier in the active component solution, but it is necessary to heat and evacuate to remove the solvent, which is harsh and cumbersome, and the yield is low. The solvent that is not removed will interfere with the catalytic reaction. The present invention directly mixes the solid phase active component cuprous chloride and the solid phase carrier hydroxyapatite, and the preparation process is simple and efficient, avoiding many problems of the above-mentioned methods, and the active component has high dispersion and good catalytic performance.

[0017] Furthermore, the mass ratio of cuprous chloride to hydroxyapatite is 1:(7-8).

[0018] Furthermore, hydroxyapatite is obtained by mixing a solution containing a calcium source and a solution containing a phosphorus source in a certain proportion, and stirring the mixture at 40 to 50°C.

[0019] Exemplarily, hydroxyapatite is prepared by mixing a solution containing a calcium source and a solution containing a phosphorus source in proportion, adjusting the pH of the reaction system to 9-13 with aqueous ammonia, stirring and reacting at 40-50° C. for 30-40 minutes to obtain a gel, standing for 24 hours, washing with deionized water, filtering, and drying in an oven at 80° C. for 12 hours. The gel is obtained by calcining at 600-800° C. for 10 hours in a muffle furnace.

[0020] The performance of supported catalysts depends on the structure of the carrier and the adsorption and distribution of the active components. The carrier acts as the skeleton of the active components, dispersing the active components and increasing the strength of the catalyst. The preparation methods of the carrier hydroxyapatite include hydrothermal method, gel method, precipitation method, etc. The preparation method of the carrier hydroxyapatite of the present invention is gel method. The carrier formed by the gel method has a mesoporous structure and a large particle size, which reduces the agglomeration and condensation of the carrier. After calcination, the microscopic mesoporous structure of the hydroxyapatite prepared by the gel method is solidified.

[0021] Specifically, the Ca / P molar ratio of the solution containing the calcium source and the solution containing the phosphorus source in the preparation process of hydroxyapatite is 1:(1.7-1.8).

[0022] Exemplarily, the Ca / P molar ratio of the solution containing the calcium source and the solution containing the phosphorus source is 1:1.7.

[0023] Exemplarily, the Ca / P molar ratio of the solution containing the calcium source and the solution containing the phosphorus source is 1:1.8.

[0024] Generally, the molar ratio of Ca / P in hydroxyapatite is 1.67, but in the present invention, Ca is appropriately excessive, the molar ratio of Ca / P is 1:(1.7-1.8), and the preferred molar ratio of Ca / P is 1:(1.74-1.78), which will increase the exchange adsorption of Ca and Cu.

[0025] Specifically, the solution containing the calcium source is any one of calcium nitrate, calcium hydroxide or calcium phosphate, preferably calcium nitrate.

[0026] Specifically, the solution containing the phosphorus source is either phosphoric acid or a phosphate, and is preferably phosphoric acid.

[0027] Illustratively, the phosphate includes, but is not limited to, potassium dihydrogen phosphate, sodium dihydrogen phosphate, diammonium hydrogen phosphate, and the like.

[0028] On the other hand, the present invention also provides a method for preparing a dimethyl carbonate solid-phase supported catalyst, wherein the hydroxyapatite and cuprous chloride are mixed in proportion, and then subjected to microwave radiation treatment to obtain a solid-phase supported catalyst, wherein the microwave radiation frequency is 2000-3000 Hz.

[0029] Exemplarily, a preparation method for preparing a dimethyl carbonate solid-phase supported catalyst is to mix hydroxyapatite and cuprous chloride in proportion, dry them at 180°C for 10 hours, and then grind them using a ball mill with a speed of 5000 r / min and a grinding time of 35 minutes; the ground powder is placed in a microwave oven, and the output frequency and time are adjusted for radiation treatment, the microwave radiation frequency is 2000 Hz, and the radiation is performed for 8 hours; the powder after microwave treatment is calcined at 500°C in a nitrogen atmosphere for 6 hours to obtain a solid-phase supported catalyst.

[0030] Exemplarily, a preparation method for preparing a dimethyl carbonate solid-phase supported catalyst is to mix hydroxyapatite and cuprous chloride in proportion, dry them at 180°C for 10 hours, and then grind them using a ball mill with a speed of 5500r / min and a grinding time of 30 minutes; the ground powder is placed in a microwave oven, and the output frequency and time are adjusted for radiation treatment, the microwave radiation frequency is 2000Hz, and the radiation is performed for 10 hours; the powder after microwave treatment is calcined at 500°C in a nitrogen atmosphere for 6 hours to obtain a solid-phase supported catalyst.

[0031] Exemplarily, a preparation method for preparing a dimethyl carbonate solid-phase supported catalyst is to mix hydroxyapatite and cuprous chloride in proportion, dry them at 180°C for 10 hours, and then grind them using a ball mill with a speed of 5500 r / min and a grinding time of 40 minutes; the ground powder is placed in a microwave oven, and the output frequency and time are adjusted for radiation treatment, the microwave radiation frequency is 2500 Hz, and the radiation is performed for 10 hours; the powder after microwave treatment is calcined at 500°C in a nitrogen atmosphere for 6 hours to obtain a solid-phase supported catalyst.

[0032] Exemplarily, a preparation method for preparing a dimethyl carbonate solid-phase supported catalyst is to mix hydroxyapatite and cuprous chloride in proportion, dry them at 180°C for 10 hours, and then grind them using a ball mill with a speed of 6000 r / min and a grinding time of 30 minutes; the ground powder is placed in a microwave oven, and the output frequency and time are adjusted for radiation treatment, the microwave radiation frequency is 3000 Hz, and the radiation is performed for 12 hours; the powder after microwave treatment is calcined at 500°C in a nitrogen atmosphere for 6 hours to obtain a solid-phase supported catalyst.

[0033] The preparation of the supported catalyst of the present invention adopts a solid phase mixing, grinding and roasting method, which promotes the adsorption of cuprous chloride on the hydroxyapatite carrier, including physical adsorption and exchange adsorption between Ca and Cu. The grinding is carried out in a ball mill, and the grinding speed and grinding time have an impact. The preferred grinding speed is between 5000-6000r / min, and the grinding time is 30-40min. The present invention also adopts a microwave solid phase method, using microwave radiation to promote the uniform distribution of active components. Microwave heating is different from ordinary conduction and convection heating methods. Its characteristics are that the microwave field can heat the entire medium at the same time, and the heating speed is very fast. Cuprous chloride is a strong microwave absorber, which heats up quickly in the microwave field and can be evenly dispersed on the carrier in a short time to prepare a supported catalyst with excellent performance. In the preparation of the supported catalyst of the present invention, the microwave radiation intensity is preferably 2000-3000Hz, and the radiation is 8-12h.

[0034] On the other hand, the present invention also provides an application of a solid-phase supported catalyst in the preparation of dimethyl carbonate. After the solid-phase supported catalyst and liquid methanol are mixed in proportion, oxygen and carbon monoxide are introduced, and the temperature and pressure are increased with continuous stirring. After a certain period of catalytic reaction, dimethyl carbonate is obtained.

[0035] Exemplarily, liquid methanol and a solid catalyst are mixed in proportion and added to a high-pressure reactor, a mixed gas of carbon monoxide and oxygen mixed in proportion is introduced, the pressure is increased to 4 MPa, the temperature is increased to 120° C., and stirring is continued. After 2 hours of catalytic reaction, dimethyl carbonate is obtained.

[0036] Exemplarily, liquid methanol and a solid catalyst are mixed in proportion and added to a high-pressure reactor, a mixed gas of carbon monoxide and oxygen mixed in proportion is introduced, the pressure is increased to 3 MPa, the temperature is increased to 130° C., and stirring is continued. After 3 hours of catalytic reaction, dimethyl carbonate is obtained.

[0037] Exemplarily, liquid methanol and a solid catalyst are mixed in proportion and added to a high-pressure reactor, a mixed gas of carbon monoxide and oxygen mixed in proportion is introduced, the pressure is increased to 3.2 MPa, the temperature is increased to 115° C., and stirring is continued. After 2.5 hours of catalytic reaction, dimethyl carbonate is obtained.

[0038] Exemplarily, liquid methanol and a solid catalyst are mixed in proportion and added to a high-pressure reactor, a mixed gas of carbon monoxide and oxygen mixed in proportion is introduced, the pressure is increased to 2 MPa, the temperature is increased to 130° C., and stirring is continued. After 3 hours of catalytic reaction, dimethyl carbonate is obtained.

[0039] Furthermore, the mass ratio of the solid phase supported catalyst to the volume ratio of the liquid phase methanol is (1-4) g:50 ml.

[0040] Exemplarily, the ratio of the mass of the solid phase supported catalyst to the volume of liquid methanol is 1g:50ml, or 2g:50ml, or 2.5g:50ml, or 4g:50ml. The embodiment of the present invention gives the ratio of the mass of the solid phase supported catalyst to the volume of liquid methanol.

[0041] Furthermore, the volume ratio of oxygen to carbon monoxide is 1:(4-7).

[0042] Exemplarily, the volume ratio of oxygen to carbon monoxide is 1:3, or 1:4, or 1:5, or 1:6, or 1:7.

[0043] Furthermore, the stirring speed of the solid-liquid catalytic reaction should not be too fast or too slow, and the catalyst particles need to be kept evenly distributed and flowing in the liquid phase. The reaction of preparing dimethyl carbonate by liquid-phase oxidative carbonylation of methanol of the present invention is carried out in an autoclave, and a stirrer is installed at the bottom, and the stirring speed is 300-600r / min.

[0044] Exemplarily, the stirring speed is 300 r / min, or 400 r / min, or 480 r / min, or 600 r / min.

[0045] Compared with the prior art, the present invention has the following beneficial effects:

[0046] (1) The amount of cuprous chloride active component in the solid phase supported catalyst of the present invention is small, which is beneficial to reduce the loss of Cl in the catalytic reaction and the corrosion of the equipment.

[0047] (2) The preparation method of the solid phase supported catalyst of the present invention adopts solid phase mixing, grinding and calcination, and further disperses the active components by microwave solid phase method, which not only ensures the adsorption distribution of Cu but also maintains the catalytic activity of Cu, and at the same time improves the stability of the catalyst.

[0048] (3) The solid phase supported catalyst of the present invention has a small catalyst dosage in the preparation of dimethyl carbonate, and the proportion of oxygen in the mixed raw gas of carbon monoxide and oxygen is low, which can reduce the risk of explosion.

[0049] (4) The solid phase supported catalyst of the present invention achieves a higher methanol conversion rate of 12 to 15% and a higher DMC selectivity of 95 to 99% in the preparation of dimethyl carbonate.

[0050] (5) In the preparation of dimethyl carbonate, the solid phase supported catalyst of the present invention can be separated from the product dimethyl carbonate by a simple separation method and can be recycled and reused. DETAILED DESCRIPTION

[0051] In order to facilitate the understanding of the present invention, the present invention will be described more comprehensively below, and preferred embodiments of the present invention are given. However, it should be understood that these embodiments are only used for more detailed description and should not be understood as limiting the present invention in any form, i.e., not intended to limit the scope of protection of the present invention.

[0052] The reagents used in the examples are all commercially available conventional reagents unless otherwise specified. The methods and conditions used in the examples are all conventional methods and conditions unless otherwise specified. Methanol is analytically pure, and other reagents are chemically pure, with carbon monoxide purity ≥95%, and oxygen purity ≥99%. The reaction products are quantitatively analyzed by gas chromatograph and area normalization method.

[0053] Preparation of solid-phase supported catalysts

[0054] Catalyst Preparation Example 1:

[0055] S1: Preparation of hydroxyapatite catalyst carrier: 200mL 0.3mol / L H3PO4 solution was slowly added to 3.6L 0.03mol / L Ca(NO3)2 while stirring, pH 10 was adjusted with ammonia water, the temperature was maintained at 45°C, and the reaction was stirred for 40min after the addition was complete to generate a gel. After standing for 24h, it was washed with deionized water, filtered, and dried in an oven at 80°C for 12h. It was calcined at 600°C in a muffle furnace for 10h to obtain hydroxyapatite carrier A.

[0056] S2: Preparation of solid phase supported catalyst: 5g hydroxyapatite carrier A and 1g cuprous chloride were mixed, dried in an oven at 180°C for 10h, then ground in a ball mill, adjusting the ball mill speed to 5000r / min, and grinding for 35min; the ground powder was placed in a microwave oven, adjusting the microwave output frequency to 2000MHz, and irradiated for 8h. The microwave-treated powder was calcined in a muffle furnace at 500°C in a nitrogen atmosphere for 6h, and naturally cooled to room temperature to obtain catalyst A.

[0057] Catalyst Preparation Example 2:

[0058] S1: Preparation of hydroxyapatite catalyst carrier: 200mL 0.3mol / L H3PO4 solution was slowly added to 3.5L 0.03mol / L Ca(NO3)2 while stirring, pH 10 was adjusted with ammonia water, the temperature was maintained at 45°C, and the reaction was stirred for 40min after the addition was complete to generate a gel. After standing for 24h, it was washed with deionized water, filtered, and dried in an oven at 80°C for 12h. It was calcined at 700°C in a muffle furnace for 10h to obtain hydroxyapatite carrier B.

[0059] S2: Preparation of solid-phase supported catalyst: 6 g of hydroxyapatite carrier B and 1 g of cuprous chloride were mixed, dried in an oven at 180°C for 10 h, and then ground in a ball mill, adjusting the ball mill speed to 5500 r / min, and grinding for 30 min; the ground powder was placed in a microwave oven, adjusting the microwave output frequency to 2000 MHz, and irradiated for 10 h. The microwave-treated powder was calcined in a muffle furnace at 500°C in a nitrogen atmosphere for 6 h, and naturally cooled to room temperature to obtain catalyst B.

[0060] Catalyst Preparation Example 3:

[0061] S1: Preparation of hydroxyapatite catalyst carrier: 200mL 0.3mol / L H3PO4 solution was slowly added to 3.5L 0.03mol / L Ca(NO3)2 while stirring, pH 10 was adjusted with ammonia water, the temperature was maintained at 45°C, and the reaction was stirred for 40min after the addition was complete to generate a gel. After standing for 24h, it was washed with deionized water, filtered, and dried in an oven at 80°C for 12h. It was calcined at 800°C in a muffle furnace for 10h to obtain hydroxyapatite carrier C.

[0062] S2: Preparation of solid-phase supported catalyst: 7g hydroxyapatite carrier C and 1g cuprous chloride were mixed, dried in an oven at 180°C for 10h, then ground in a ball mill, adjusting the ball mill speed to 5500r / min, and grinding for 40min; the ground powder was placed in a microwave oven, adjusting the microwave output frequency to 2500MHz, and irradiated for 10h. The microwave-treated powder was calcined in a muffle furnace at 500°C in a nitrogen atmosphere for 6h, and naturally cooled to room temperature to obtain catalyst C.

[0063] Catalyst Preparation Example 4:

[0064] S1: Preparation of hydroxyapatite catalyst carrier: 200mL 0.3mol / L H3PO4 solution was slowly added to 3.4L 0.03mol / L Ca(NO3)2 while stirring, pH 10 was adjusted with ammonia water, the temperature was maintained at 45°C, and the reaction was stirred for 40min after the addition was complete to generate a gel. After standing for 24h, it was washed with deionized water, filtered, and dried in an oven at 80°C for 12h. It was calcined at 600°C in a muffle furnace for 10h to obtain hydroxyapatite carrier D.

[0065] S2: Preparation of solid phase supported catalyst: 8g hydroxyapatite carrier D and 1g cuprous chloride were mixed, dried in an oven at 180°C for 10h, and then ground in a ball mill, adjusting the ball mill speed to 6000r / min, and grinding for 30min. The ground powder was placed in a microwave oven, the microwave output frequency was adjusted to 3000MHz, and irradiated for 12h. The microwave-treated powder was calcined in a muffle furnace at 500°C in a nitrogen atmosphere for 6h, and naturally cooled to room temperature to obtain catalyst D.

[0066] Preparation of solid phase supported catalyst comparative example

[0067] Catalyst Preparation Comparative Example 1

[0068] S1: Preparation of hydroxyapatite catalyst carrier: 200mL 0.3mol / L H3PO4 solution was slowly added to 4L 0.025mol / L Ca(NO3)2 while stirring, pH 10 was adjusted with ammonia water, the temperature was maintained at 45°C, and the reaction was stirred for 40 minutes after the addition was completed to generate a gel. After standing for 24 hours, it was washed with deionized water, filtered, and dried in an oven at 80°C for 12 hours. It was calcined at 600°C in a muffle furnace for 10 hours to obtain hydroxyapatite carrier E.

[0069] S2: Preparation of solid-phase supported catalyst: 7 g of hydroxyapatite carrier E and 1 g of cuprous chloride were mixed, dried in an oven at 180°C for 10 h, and then ground in a ball mill, adjusting the ball mill speed to 6000 r / min, and grinding for 30 min. The ground powder was placed in a microwave oven, adjusting the microwave output frequency to 3000 MHz, and irradiated for 12 h. The microwave-treated powder was calcined in a muffle furnace at 500°C in a nitrogen atmosphere for 6 h, and naturally cooled to room temperature to obtain catalyst E.

[0070] Catalyst Preparation Comparative Example 2

[0071] S1: Preparation of hydroxyapatite catalyst carrier: 200mL 0.3mol / L H3PO4 solution was slowly added to 3.5L 0.025mol / L Ca(NO3)2 while stirring, pH 10 was adjusted with ammonia water, the temperature was maintained at 45°C, and the reaction was stirred for 40min after the addition was complete to generate a gel. After standing for 24h, it was washed with deionized water, filtered, and dried in an oven at 80°C for 12h. It was calcined at 600°C in a muffle furnace for 10h to obtain hydroxyapatite carrier F.

[0072] S2: Preparation of solid phase supported catalyst: 10g hydroxyapatite carrier F and 1g cuprous chloride were mixed, dried in an oven at 180°C for 10h, and then ground in a ball mill, adjusting the ball mill speed to 6000r / min, and grinding for 30min. The ground powder was placed in a microwave oven, the microwave output frequency was adjusted to 3000MHz, and irradiated for 12h. The microwave-treated powder was calcined in a muffle furnace at 500°C in a nitrogen atmosphere for 6h, and naturally cooled to room temperature to obtain catalyst F.

[0073] Catalyst Preparation Comparative Example 3

[0074] S1: Preparation of hydroxyapatite catalyst carrier: Mix 200mL of 0.3mol / L (NH4)2HPO4 and 200mL of 0.5mol / L Ca(NO3)2 solution, adjust the pH of the solution to 9 with ammonia water, stir it thoroughly, and then place it in a closed autoclave, heat it to 150°C, and react at a constant temperature for 10 hours. After the autoclave is cooled to room temperature, take out the reactants, filter and wash them, and dry them at 80°C to obtain hydroxyapatite carrier G.

[0075] S2: Preparation of solid phase supported catalyst: 8g hydroxyapatite carrier G and 1g cuprous chloride were mixed, dried in an oven at 180°C for 10h, and then ground in a ball mill, adjusting the ball mill speed to 6000r / min, and grinding for 30min. The ground powder was placed in a microwave oven, the microwave output frequency was adjusted to 3000MHz, and irradiated for 12h. The microwave-treated powder was calcined in a muffle furnace at 500°C in nitrogen for 6h, and naturally cooled to room temperature to obtain catalyst G.

[0076] Application of solid-phase supported catalyst in the preparation of dimethyl carbonate

[0077] Example 1

[0078] 50 ml of methanol and 1 g of catalyst A were mixed and added to a 250 ml autoclave, and a mixed gas of carbon monoxide and oxygen was introduced, with a volume ratio of carbon monoxide to oxygen of 7:1. When the pressure was raised to 4 MPa, the temperature was raised to 120°C, stirring was continued at a stirring speed of 300 r / mi, and after 2 hours of catalytic reaction, crude dimethyl carbonate was obtained. The results of gas chromatography analysis showed that the methanol conversion rate was 12% and the DMC selectivity was 95%.

[0079] Example 2

[0080] 50 ml of methanol and 2 g of catalyst B were mixed and added to a 250 ml autoclave, and a mixed gas of carbon monoxide and oxygen was introduced, with a volume ratio of carbon monoxide to oxygen of 6:1. When the pressure was raised to 3 MPa, the temperature was raised to 130°C, stirring was continued at a stirring speed of 400 r / min, and after 3 hours of catalytic reaction, crude dimethyl carbonate was obtained. The results of gas chromatograph analysis showed that the methanol conversion rate was 13% and the DMC selectivity was 97%.

[0081] Example 3

[0082] 50 ml of methanol and 2.5 g of catalyst C were mixed and added to a 250 ml autoclave, and a mixed gas of carbon monoxide and oxygen was introduced, with a volume ratio of carbon monoxide to oxygen of 5:1. When the pressure rose to 3.2 MPa, the temperature was raised to 115°C, stirring was continued at a stirring speed of 480 r / min, and after 2.5 hours of catalytic reaction, crude dimethyl carbonate was obtained. The results of gas chromatograph analysis showed a methanol conversion rate of 15% and a DMC selectivity of 99%.

[0083] Example 4

[0084] 50ml methanol and 4g catalyst D were mixed and added to a 250ml autoclave, and a mixed gas of carbon monoxide and oxygen was introduced, with a volume ratio of carbon monoxide to oxygen of 4:1. When the pressure was raised to 2MPa, the temperature was raised to 130°C, stirring was continued at a stirring speed of 600r / min, and after 3 hours of catalytic reaction, crude dimethyl carbonate was obtained. The results of gas chromatography analysis showed that the methanol conversion rate was 14% and the DMC selectivity was 98%.

[0085] Comparative Example 1

[0086] 50ml methanol and 2.5g catalyst E were mixed and added to a 250ml autoclave, and a mixed gas of carbon monoxide and oxygen was introduced, with a volume ratio of carbon monoxide to oxygen of 4:1. When the pressure was raised to 2MPa, the temperature was raised to 130°C, stirring was continued at a stirring speed of 600r / min, and after 3 hours of catalytic reaction, crude dimethyl carbonate was obtained. The results of gas chromatography analysis showed that the methanol conversion rate was 10% and the DMC selectivity was 92.8%.

[0087] Comparative Example 2

[0088] 50ml methanol and 2g catalyst F were mixed and added to a 250ml autoclave, and a mixed gas of carbon monoxide and oxygen was introduced, with a volume ratio of carbon monoxide to oxygen of 10:1. When the pressure was raised to 2MPa, the temperature was raised to 130°C, stirring was continued at a stirring speed of 600r / min, and after 3 hours of catalytic reaction, crude dimethyl carbonate was obtained. The results of gas chromatography analysis showed a methanol conversion rate of 8% and a DMC selectivity of 93%.

[0089] Comparative Example 3

[0090] 50ml methanol and 2g catalyst G were mixed and added to a 250ml autoclave, and a mixed gas of carbon monoxide and oxygen was introduced, with a volume ratio of carbon monoxide to oxygen of 6:1. When the pressure was raised to 2MPa, the temperature was raised to 130°C, stirring was continued at a stirring speed of 600r / min, and after 3 hours of catalytic reaction, crude dimethyl carbonate was obtained. The results of gas chromatography analysis showed a methanol conversion rate of 5% and a DMC selectivity of 92%.

[0091] The experimental results of Examples 1-4 and Comparative Examples 1-3 are shown in Table 1:

[0092] Table 1

[0093]

[0094]

[0095] As shown in the results of Table 1, the methanol conversion rate in Examples 1-4 is 12-15%, and the DMC selectivity is 95-99%. Among them, the methanol conversion rate and DMC selectivity of dimethyl carbonate prepared by using catalyst C in Example 2 are the highest. The comparative examples show the influence of the main factors. The Ca / P ratio prepared by hydroxyapatite in Comparative Example 1 is the theoretical value of 1.67, and its methanol conversion rate and DMC selectivity are not as high as the Ca / P ratio prepared by hydroxyapatite of 1: (1.7-1.8). The amount of catalyst active components in Comparative Example 2 and the volume ratio of raw gas exceed the optimal range of the present invention. Comparative Example 3 uses a hydrothermal method to prepare hydroxyapatite, and the methanol conversion rate and DMC selectivity of the catalytic reaction are lower than those of the present invention.

[0096] Solid phase supported catalyst recovery test

[0097] After the used solid phase supported catalysts A-D were washed with solvent and dried, 50ml of methanol was mixed with 2.5g of catalysts A-D and added to a 250ml high pressure reactor, and a mixed gas of carbon monoxide and oxygen was introduced, with a volume ratio of carbon monoxide to oxygen of 5:1. When the pressure was raised to 3.2MPa, the temperature was raised to 115°C, stirring was continued at a stirring speed of 480r / min, and crude dimethyl carbonate was obtained after 2.5 hours of catalytic reaction. According to gas chromatograph analysis, the recovery test can still achieve a methanol conversion rate of 12-15%, a DMC selectivity of 95-99%, and the catalytic activity is basically maintained.

[0098] In the present invention, unless otherwise specified, all the technical features and preferred features mentioned herein can be combined with each other to form a new technical solution.

[0099] The above embodiments are intended to illustrate the substantial content of the present invention, but are not intended to limit the protection scope of the present invention. A person skilled in the art should understand that, without departing from the principle of the present invention, the technical solution of the present invention may be modified and embellished in a number of ways without departing from the essence and protection scope of the technical solution of the present invention.

Claims

1. A solid phase supported catalyst for preparing dimethyl carbonate, the solid phase supported catalyst comprising an active component and a carrier, characterized in that: The active component is cuprous chloride, the carrier is hydroxyapatite, and the mass ratio of cuprous chloride to hydroxyapatite is 1:(5-8).

2. A solid phase supported catalyst for preparing dimethyl carbonate according to claim 1, characterized in that: The mass ratio of cuprous chloride to hydroxyapatite is 1:(7-8).

3. A solid phase supported catalyst for preparing dimethyl carbonate according to claim 1, characterized in that: The hydroxyapatite is obtained by mixing a solution containing a calcium source and a solution containing a phosphorus source in proportion, and stirring the mixture at 40 to 50° C.

4. A solid phase supported catalyst for preparing dimethyl carbonate according to claim 2, characterized in that: The Ca / P molar ratio of the solution containing the calcium source and the solution containing the phosphorus source is 1:(1.7-1.8).

5. A solid phase supported catalyst for preparing dimethyl carbonate according to claim 2, characterized in that: The solution containing a calcium source is any one of calcium nitrate, calcium hydroxide or calcium phosphate, preferably calcium nitrate.

6. A solid phase supported catalyst for preparing dimethyl carbonate according to claim 2, characterized in that: The solution containing a phosphorus source is any one of phosphoric acid or phosphate, preferably phosphoric acid.

7. A method for preparing a solid phase supported catalyst for preparing dimethyl carbonate as claimed in any one of claims 1 to 6, characterized in that: The hydroxyapatite and cuprous chloride are mixed in proportion and then subjected to microwave radiation treatment to obtain a solid phase supported catalyst, wherein the microwave radiation frequency is 2000-3000 Hz.

8. Use of the solid phase supported catalyst according to any one of claims 1 to 6 in the preparation of dimethyl carbonate, characterized in that: The solid phase supported catalyst and liquid phase methanol are mixed in proportion, and oxygen and carbon monoxide are introduced to obtain dimethyl carbonate.

9. Use of a solid phase supported catalyst in the preparation of dimethyl carbonate according to claim 8, characterized in that: The mass ratio of the solid phase supported catalyst to the volume ratio of the liquid phase methanol is (1-4) g:50 ml.

10. Use of a solid phase supported catalyst in the preparation of dimethyl carbonate according to claim 8, characterized in that: The volume ratio of oxygen to carbon monoxide is 1:(4-7).

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