CN112439405B

CN112439405B - Catalyst for preparing dimethyl carbonate from methanol, carbon dioxide and 2-cyanopyridine and preparation method and application thereof

Info

Publication number: CN112439405B
Application number: CN202011513927.7A
Authority: CN
Inventors: 宋清文; 刘平; 张侃; 张乾霞; 韩丽华; 荀家瑶; 刘增厚
Original assignee: Shanxi Institute of Coal Chemistry of CAS
Current assignee: Shanxi Institute of Coal Chemistry of CAS
Priority date: 2020-12-21
Filing date: 2020-12-21
Publication date: 2022-03-11
Anticipated expiration: 2040-12-21
Also published as: CN112439405A

Abstract

The invention relates to the field of dimethyl carbonate preparation, and discloses a catalyst for preparing dimethyl carbonate from methanol, carbon dioxide and 2-cyanopyridine, which comprises 0.5-20% of metal oxide, 0.5-2% of additive and the balance of carrier in percentage by weight. The invention also relates to a preparation method and application of the catalyst. The preparation process of the catalyst does not use any organic solvent and noble metal, has low cost and is easy for large-scale production.

Description

Catalyst for preparing dimethyl carbonate from methanol, carbon dioxide and 2-cyanopyridine and preparation method and application thereof

Technical Field

The invention relates to the field of preparation of dimethyl carbonate by using methanol, carbon dioxide and 2-cyanopyridine.

Background

Carbon dioxide (CO)₂) Is an environment-friendly renewable carbon raw material and can be applied to the preparation of various compounds and clean fuels. Dimethyl carbonate is a green chemical and has wide application and market. The ideal synthetic route is methanol and CO₂The byproduct of the reaction is water. China is rich in coal resources, and along with the development of coal chemical industry, CO₂Discharge is inevitable. In addition, the technology for preparing methanol by a coal-based route is mature, and methanol and CO are used₂The dimethyl carbonate is synthesized as the raw material, which not only can broaden the utilization channel of the methanol, but also can effectively realize the CO₂Thereby achieving high-value utilization. The industrialization of the route can expand and promote the development of the technology for preparing chemicals by clean utilization of coal.

There are many routes reported for preparing dimethyl carbonate at home and abroad, but examples for realizing industrialization are very limited. Among them are the methanol carbon monoxide oxidative carbonylation reaction method, the two-step ester exchange method and the vicinal diol urea method (figure 1). Among them, the oxidative carbonylation method uses toxic carbon monoxide, and the copper-based catalyst is also easily corroded and damaged in the catalytic process, still facing the technical bottleneck. The ortho-diol urea method has been established into a ten-thousand-ton industrial demonstration device, and the process has long process flow, complex separation and high energy consumption. The existing industrial preparation route of dimethyl carbonate is mainly a two-step method, namely ethylene oxide (propane) and CO₂The reaction produces ethylene (propylene) carbonate, which is then transesterified with methanol to produce dimethyl carbonate. The method uses epoxide with low boiling point and toxicity, and simultaneously coproduces ethylene glycol or 1, 2-propylene glycol with equal mole, has low utilization rate of raw materials and high cost, thereby limiting the application range of the method.

Methanol and CO₂The direct reaction method is the most ideal method for preparing dimethyl carbonate, but is limited by thermodynamic equilibrium and has great challenges, which is also a worldwide problem. The effective dehydrating agent used in the research can promote the forward and high-efficiency reaction. 2013 reports that 2-cyanopyridine is used as a high-efficiency dehydrating agent to realize near-quantitative conversion reaction of methanol, and the dehydrating agent can be recycled by catalysis (ChemSusChem 2013, 6, 1341)But the efficiency of cyclic regeneration is low. On the basis that the dehydrating agent can be efficiently recycled, a high-efficiency economic technical scheme can be finally established. Therefore, industrialization can be finally realized by developing a series of high-efficiency catalytic technologies for researching the reaction scheme process.

At present, methanol, carbon dioxide and 2-cyanopyridine react to generate a large amount of byproducts such as 2-picolinic acid methyl ester and carbamic acid methyl ester with low added values. On one hand, the dehydrating agent is consumed in the byproduct generation process, so that the cost is increased; on the other hand, the by-products bring difficulty to the separation and purification of the products, the process is more complicated, and the energy consumption is greatly increased. Therefore, it is of great importance to develop a catalyst which is inexpensive, highly active, highly selective and has a long life. The technology relates to the development of a novel high-efficiency heterogeneous metal catalyst for realizing methanol and CO₂And 2-cyanopyridine to prepare dimethyl carbonate through coupling high-selectivity catalytic reaction.

Disclosure of Invention

The invention aims to provide a novel catalyst for preparing dimethyl carbonate from methanol, carbon dioxide and 2-cyanopyridine and application thereof.

The technical scheme adopted by the invention is as follows: a catalyst for preparing dimethyl carbonate from methanol, carbon dioxide and 2-cyanopyridine comprises 0.5-20% of metal oxide, 0.5-2% of additive and the balance of carrier in percentage by weight.

The metal oxide is one or more of Zn, Co, Zr, Fe, Cr, Mn, Ni, Ce and La oxides.

The additive is phosphoric acid or boric acid.

The carrier is gamma-Al 2O3 or SiO 2.

A preparation method of a catalyst for preparing dimethyl carbonate from methanol, carbon dioxide and 2-cyanopyridine comprises the following steps

Step one, preparing a metal or mixed metal nitrate solution with metal cation concentration of 0.1-0.50 g.mL < -1 >;

step two, adding a carrier into a metal or mixed metal nitrate solution, uniformly stirring, then adding an aqueous solution of an additive, uniformly stirring and mixing again, soaking for 1-12 h, then baking for 2-24 h at 60-150 ℃, grinding the obtained solid, and baking for 3-12 h at 300-550 ℃ to obtain the catalyst.

The metal or the metal in the mixed metal nitrate solution is one or more of Zn, Co, Zr, Fe, Cr, Mn, Ni, Ce and La.

The additive is 0.01-2 mol/L phosphoric acid or 0.01-2 mol/L boric acid aqueous solution.

The carrier is 50-99 wt% of gamma-Al 2O3 or SiO2, and the particle size is 15-150 nm.

The application of the catalyst for preparing dimethyl carbonate by using methanol, carbon dioxide and 2-cyanopyridine is characterized in that: the method is used for three-component coupling reaction of methanol, CO2 and 2-cyanopyridine, and the reaction conditions are as follows: methanol and 2-cyanopyridine are mixed and dissolved mutually according to the molar ratio of 1: 5-5: 1, then fed in a liquid form, and CO2 is fed in a gas state, wherein the liquid material accounts for 10-50% of the volume ratio of the reactor, the reaction temperature is 80-160 ℃, and CO 2-0.1-6 MPa is filled.

The molar ratio of the catalyst to the methanol is 0.05-0.2, and the residence time of reactants in the reaction bed is controlled to be 1-8 hours.

From thermodynamic analysis, the coupling reaction is a rapid exothermic reaction, and the reaction temperature has a great influence on the reaction rate and the reaction selectivity of the reaction. The catalytic amount of the reaction is too high, the reaction releases heat violently, temperature runaway is easy to cause technically, the requirement on condensation control equipment is improved, and the economy is further reduced; from the chemical analysis, the temperature runaway easily causes unstable reaction, and simultaneously aggravates the occurrence of side reaction, the chemical selectivity is reduced, and the product separation difficulty and the energy consumption are correspondingly increased. The setting of the ratio of the supported composite metal catalyst to the reaction raw material depends on the simple control of the actual reaction conditions and the requirements of the generation rate, the selectivity and the yield index of the product.

The technical advantages of the invention are as follows: the invention discloses a supported composite metal catalyst prepared by an impregnation method. Compared with the existing reported cerium-based catalyst, the method has the substantial characteristics and the progress that:

(1) the non-noble metal is used as the catalytic component, so that the cost is low, the preparation method is simple and practical, and the large-scale production is facilitated; the roasting temperature is low, the performance is high, and the method has important significance for reducing the energy consumption cost;

(2) the reported catalyst has high use pressure and simultaneously has inevitable side reaction, thereby seriously reducing the chemical selectivity; the preparation method of the novel catalyst is simple, has high activity and simple operation, and has important significance for improving the productivity;

(3) the catalyst has the advantages that multiple components interact, the acidity and the alkalinity of the catalyst are effectively adjusted, the advantages of high activity and high selectivity can be better embodied, and the catalyst is used for preparing dimethyl carbonate by using methanol, carbon dioxide and 2-cyanopyridine, which is not reported;

(4) catalytic efficiency of the catalyst: the conversion rate of methanol is 50-100%, the selectivity of dimethyl carbonate is greater than or equal to 99%, the catalyst can be recycled for at least more than 30 times, and the activity is not obviously reduced.

Drawings

FIG. 1 is a scheme for the preparation of dimethyl carbonate.

Detailed Description

The following provides a more detailed description of embodiments of the present invention by way of specific examples.

Example 1

The concentration of Cr ions is 0.1 g/mL^-16 mL of the chromium nitrate solution, and gamma-Al having a particle size of 20 nm was added to the solution₂O₃8.9 g of solid is stirred uniformly, then 10 mL of H3BO3 solution with the concentration of 0.9 mol/L is added, the mixture is stirred and mixed uniformly again, the mixture is soaked for 6H, then the mixture is dried for 12H at the temperature of 100 ℃, the obtained solid is ground, and the mixture is roasted for 6H at the temperature of 400 ℃ to obtain the catalyst. 10 g of the catalyst raw powder was charged into a tank reactor. Methanol and 2-cyanopyridine are mixed and dissolved mutually according to the molar ratio of 3:1 and then fed in a liquid form, the liquid material accounts for 12 percent of the volume of the reactor, CO2 is fed in a gaseous state, CO2 to 1MPa is filled, the reaction temperature is 100 ℃, the mass ratio of the catalyst to the methanol is 0.06, the retention time of reactants in a reaction bed layer is 8 hours, the conversion rate of the methanol is 88.7 percent, the DMC selectivity is 100 percent, the circulation frequency of the catalyst is 35 times, and the circulation operation process is implementedThe catalyst activity was not significantly reduced.

Example 2

The Zr ion concentration is prepared to be 0.07 g/mL^-110 mL of zirconium nitrate solution, to which SiO having a particle size of 20 nm was added₂8.95 g of solid was stirred well, and then H was added thereto at a concentration of 0.45 mol/L₃BO₃And stirring and mixing the solution 10 mL again, soaking for 6 h, drying at 100 ℃ for 16 h, grinding the obtained solid, and roasting at 400 ℃ for 10 h to obtain the catalyst. 10 g of the catalyst raw powder was charged into a tank reactor. Methanol and 2-cyanopyridine are mixed and dissolved mutually according to the molar ratio of 1:1 and then fed in a liquid form, the liquid material accounts for 25 percent of the volume of the reactor, CO2 is fed in a gaseous state, CO2 to 5 MPa is filled, the reaction temperature is 120 ℃, the mass ratio of the catalyst to the methanol is 0.05, the retention time of reactants in a reaction bed layer is 8 hours, the conversion rate of the methanol is 91.2 percent, the DMC selectivity is 100 percent, the circulation frequency of the catalyst is 41 times, and the activity of the catalyst is not obviously reduced in the circulating operation process.

Example 3

The concentration of Mn ions prepared was 0.15 g/mL^-110 mL of the manganese nitrate solution (Ni ion concentration: 0.08 g/mL)^-110 mL of the nickel nitrate solution, and gamma-Al having a particle size of 50 nm was added to the mixed solution₂O₃16.6 g of solid, and stirring them uniformly, then adding H with a concentration of 0.7 mol/L₃And 20mL of PO4 solution is stirred and mixed uniformly again, the mixture is soaked for 8 h, then the solid is dried for 8 h at the temperature of 120 ℃, the obtained solid is ground, and the solid is roasted for 4 h at the temperature of 500 ℃ to obtain the catalyst. 10 g of the catalyst raw powder was charged into a tank reactor. Methanol and 2-cyanopyridine are mixed and dissolved mutually according to the molar ratio of 1:2 and then fed in a liquid form, the liquid material accounts for 25 percent of the volume of the reactor, and CO is added₂Feeding in gaseous form, CO-charging₂The reaction temperature is 115 ℃, the mass ratio of the catalyst to the methanol is 0.1, the residence time of reactants in the reactor is 6 h, the conversion rate of the methanol is 83.5 percent, the DMC selectivity is 100 percent, the cycle number of the catalyst is 32 times, and the activity of the catalyst is not obviously reduced in the process of cyclic operation.

Example 4

The concentration of La ions prepared was 0.17 g/mL^-110 mL of lanthanum nitrate solution (Ce ion concentration: 0.16 g/mL)^-110 mL of the cesium nitrate solution, and SiO having a particle diameter of 50 nm was added to the mixed solution₂15.72 g of solid, and stirring them uniformly, then adding H with a concentration of 0.45 mol/L₃PO₄And stirring and mixing the solution 20mL again, soaking for 8 h, drying at 120 ℃ for 8 h, grinding the obtained solid, and roasting at 450 ℃ for 8 h to obtain the catalyst. 10 g of the catalyst raw powder was charged into a tank reactor. Methanol and 2-cyanopyridine are mixed and dissolved mutually according to the molar ratio of 1:3 and then fed in a liquid form, wherein the liquid material accounts for 10 percent of the volume of the reactor, and CO is₂Feeding in gaseous form, CO-charging₂The reaction temperature is 150 ℃, the mass ratio of the catalyst to the methanol is 0.15, the retention time of reactants in a reaction bed layer is 6 h, the conversion rate of the methanol is 85.8 percent, the DMC selectivity is 99.4 percent, the cycle number of the catalyst is 38 times, and the activity of the catalyst is not obviously reduced in the process of cycle operation.

Example 5

The Zn ion concentration was adjusted to 0.01 g/mL^-1In the zinc nitrate solution (10 mL), the Co ion concentration was 0.01 g/mL^-110 mL of cobalt nitrate solution (Fe ion concentration: 0.01 g/mL)^-110 mL of the iron nitrate solution, and gamma-Al having a particle size of 80 nm was added to the mixed solution₂O₃14.5 g of solid, and stirring them uniformly, then adding H with a concentration of 0.8 mol/L₃BO₃And stirring and mixing the solution 10 mL again, soaking for 10 h, drying at 150 ℃ for 18 h, grinding the obtained solid, and roasting at 550 ℃ for 3 h to obtain the catalyst. 10 g of the catalyst raw powder was charged into a tank reactor. Methanol and 2-cyanopyridine are mixed and dissolved mutually according to the molar ratio of 1:4.5 and then fed in a liquid form, the liquid material accounts for 43 percent of the volume of the reactor, and CO accounts for₂Feeding in gaseous form, CO-charging₂The pressure is 0.8 MPa, the reaction temperature is 160 ℃, the mass ratio of the catalyst to the methanol is 0.12, the retention time of reactants in a reaction bed layer is 8 hours, the conversion rate of the methanol is 96.1 percent, the DMC selectivity is 100 percent, and the catalyst is usedThe catalyst activity was not significantly reduced during the circulation operation, since the number of the catalyst circulations was 40.

Example 6

The Ni ion concentration was adjusted to 0.14 g/mL^-110 mL of the nickel nitrate solution, and SiO having a particle size of 80 nm was added to the solution₂12.9 g of solid is stirred uniformly, then 30 mL of H3PO4 solution with the concentration of 0.3 mol/L is added, the mixture is stirred and mixed uniformly again, the mixture is soaked for 10H, then the mixture is dried for 20H at the temperature of 150 ℃, the obtained solid is ground, and the mixture is roasted for 8H at the temperature of 450 ℃ to obtain the catalyst. 10 g of the catalyst raw powder was charged into a tank reactor. Methanol and 2-cyanopyridine are mixed and mutually dissolved according to the molar ratio of 2:1 and then fed in a liquid form, the liquid material accounts for 22 percent of the volume of the reactor, CO2 is fed in a gaseous state, CO2 is filled to 3.2 MPa, the reaction temperature is 80 ℃, the mass ratio of the catalyst to the methanol is 0.04, the residence time of reactants in a reaction bed layer is 5 hours, the conversion rate of the methanol is 79.6 percent, the DMC selectivity is 100 percent, the cycle number of the catalyst is 43 times, and the activity of the catalyst is not obviously reduced in the process of circulating operation.

Example 7

The concentration of Fe ions prepared was 0.17 g/mL^-110 mL of the ferric nitrate solution (5), the Cr ion concentration being 0.2 g/mL^-110 mL of the chromium nitrate solution, and gamma-Al having a particle size of 120 nm was added to the mixed solution₂O₃24.3 g of solid is stirred uniformly, then 200 mL of H3BO3 solution with the concentration of 1.5 mol/L is added, the mixture is stirred and mixed uniformly again, the mixture is soaked for 12H and then dried for 20H at the temperature of 80 ℃, the obtained solid is ground, and the mixture is roasted for 6H at the temperature of 460 ℃ to obtain the catalyst. 10 g of the catalyst raw powder was charged into a tank reactor. Methanol and 2-cyanopyridine are mixed and mutually dissolved according to the molar ratio of 5:1 and then fed in a liquid form, the liquid material accounts for 27.5 percent of the volume of the reactor, CO2 is fed in a gaseous state, CO2 to 6 MPa is filled, the reaction temperature is 90 ℃, the mass ratio of the catalyst to the methanol is 0.02, the residence time of reactants in a reaction bed layer is 4 hours, the conversion rate of the methanol is 84.3 percent, the DMC selectivity is 100 percent, the cycle number of the catalyst is 39 times, and the activity of the catalyst is not obviously reduced in the process of circulating operation.

Example 8

The concentration of La ions prepared was 0.2 g/mL^-1Adding 27 g of SiO2 solid with the particle size of 120 nm into the solution, stirring uniformly, then adding 50 mL of H3PO4 solution with the concentration of 0.04 mol/L, stirring uniformly again, soaking for 12H, drying for 24H at 80 ℃, grinding the obtained solid, and roasting for 10H at 420 ℃ to obtain the catalyst. 10 g of the catalyst raw powder was charged into a tank reactor. Methanol and 2-cyanopyridine are mixed and dissolved mutually according to the molar ratio of 3:1 and then fed in a liquid form, the liquid material accounts for 23 percent of the volume of the reactor, CO2 is fed in a gaseous state, CO2 to 0.3MPa is filled, the reaction temperature is 85 ℃, the mass ratio of the catalyst to the methanol is 0.03, the retention time of reactants in a reaction bed layer is 6 hours, the conversion rate of the methanol is 83.9 percent, the DMC selectivity is 99.6 percent, the cycle number of the catalyst is 33 times, and the activity of the catalyst is not obviously reduced in the process of circulating operation.

Comparative example 1

The concentration of Cr ions is 0.1 g/mL^-118 mL of the chromium nitrate solution, and gamma-Al having a particle size of 20 nm was added to the solution₂O₃7 g, stirring uniformly, soaking for 6 h, drying at 100 ℃ for 12 h, grinding the obtained solid, and roasting at 400 ℃ for 6 h to obtain the catalyst. 10 g of the catalyst raw powder was charged into a tank reactor. Methanol and 2-cyanopyridine are mixed and mutually dissolved according to the molar ratio of 1:4 and then fed in a liquid form, the liquid material accounts for 45 percent of the volume of the reactor, CO2 is fed in a gaseous state, CO2 to 1MPa is filled, the reaction temperature is 100 ℃, the mass ratio of the catalyst to the methanol is 0.3, the retention time of reactants in a reaction bed layer is 8 hours, the conversion rate of the methanol is 25 percent, the DMC selectivity is 36 percent, the cycle number of the catalyst is 3 times, and the activity of the catalyst is obviously reduced in the process of cycle operation.

Comparative example 2

The concentration of Mn ions prepared was 0.15 g/mL^-110 mL of manganese nitrate solution, to which was added gamma-Al having a particle size of 200 nm₂O₃13 g of the mixture is stirred evenly, and then H with the concentration of 2 mol/L is added₃PO₄Stirring the solution 20mL again, mixing well, soaking for 8 h, drying at 120 deg.C for 20 h, grinding the obtained solid, 420^℃Roasting for 10 hours under the condition to obtain the catalyst. 10 g of the catalyst raw powder was charged into a tank reactor. Methanol and 2-cyanopyridine are mixed and dissolved mutually according to the molar ratio of 1:12 and then fed in a liquid form, wherein the liquid material accounts for 26 percent of the volume of the reactor, and CO is₂Feeding in gaseous form, CO-charging₂The reaction temperature is 115 ℃, the mass ratio of the catalyst to the methanol is 0.5, the residence time of reactants in a reaction bed layer is 8 h, the conversion rate of the methanol is 38%, the DMC selectivity is 44%, the cycle number of the catalyst is 6, and the activity of the catalyst is obviously reduced in the process of cyclic operation.

Comparative example 3

The concentration of Fe ions prepared was 0.17 g/mL^-1Adding ZSM-1124.3 g with the particle size of 200 nm into the solution, stirring uniformly, impregnating for 12 hours, drying for 20 hours at the temperature of 80 ℃, grinding the obtained solid, and roasting for 6 hours at the temperature of 460 ℃ to obtain the catalyst. 10 g of the catalyst raw powder was charged into a tank reactor. Methanol and 2-cyanopyridine are mixed and dissolved mutually according to the molar ratio of 1:5 and then fed in a liquid form, wherein the liquid material accounts for 57.5 percent of the volume of the reactor, and CO is₂Feeding in gaseous form, CO-charging₂The reaction temperature is 90 ℃, the mass ratio of the catalyst to the methanol is 0.1, the residence time of reactants in a reaction bed layer is 8 hours, the conversion rate of the methanol is 46.9 percent, the DMC selectivity is 37.2 percent, the cycle number of the catalyst is 8 times, and the activity of the catalyst is obviously reduced in the process of cyclic operation.

Claims

1. A catalyst for preparing dimethyl carbonate from methanol, carbon dioxide and 2-cyanopyridine is characterized in that: the catalyst comprises 0.5-20 wt% of metal oxide, 0.5-2 wt% of additive and the balance of carrier, wherein the metal oxide is one or more of Zn, Co, Zr, Fe, Cr, Mn, Ni, Ce and La oxides, the additive is phosphoric acid or boric acid, and the carrier is gamma-Al₂O₃Or SiO₂Preparation method of catalystThe method comprises the following steps

Step one, preparing metal cation with the concentration of 0.1-0.50 g/mL^-1Metal or mixed metal nitrate solutions of (a);

2. The catalyst of claim 1, wherein: the additive is 0.01-2 mol/L phosphoric acid or 0.01-2 mol/L boric acid aqueous solution.

3. The catalyst of claim 1, wherein: the carrier is 50-99 wt% of gamma-Al₂O₃Or SiO₂The grain diameter is 15-150 nm.

4. Use of a catalyst as claimed in claim 1, wherein: for methanol and CO₂And 2-cyanopyridine, wherein the reaction conditions are as follows: methanol and 2-cyanopyridine are mixed and dissolved mutually according to the molar ratio of 1: 5-5: 1, then fed in a liquid form, and CO is fed₂Feeding in a gaseous state, wherein the liquid material accounts for 10-50% of the volume of the reactor, the reaction temperature is 80-160 ℃, and filling CO₂To 0.1 to 6 MPa.

5. Use of a catalyst according to claim 4, characterized in that: the molar ratio of the catalyst to the methanol is 0.05-0.2, and the residence time of reactants in the reaction bed is controlled to be 1-8 hours.