阅读说明：本技术 一种合成甲基丙烯酸甲酯的催化剂及其应用方法 (Catalyst for synthesizing methyl methacrylate and application method thereof ) 是由 李春山 邓森林 张国梁 李�杰 常炜 王蕾 张军平 张锁江 于 2021-02-02 设计创作，主要内容包括：本发明公开了一种丙酸甲酯和甲醛制甲基丙烯酸甲酯的催化剂及其制备方法。催化剂的主活性组分为Cs和Al,助剂为Zr、La、Ce和Zn中的一种以上,载体为多孔SiO-2选自孔径2nm-12nm中的一种。以载体为基准,按氧化物计,主活性组分Cs和Al的负载量分别为5wt.％～20wt.％和1wt.％～10wt.％,助剂的负载量为0.1wt.％～5wt.％。所述的催化剂具有较好的活性、选择性和稳定性,制备工艺简单,适合大规模工业化应用。(The invention discloses a catalyst for preparing methyl methacrylate from methyl propionate and formaldehyde and a preparation method thereof. The main active components of the catalyst are Cs and Al, the auxiliary agent is more than one of Zr, La, Ce and Zn, and the carrier is porous SiO 2 One selected from the group consisting of pore diameters of 2nm to 12 nm. Based on the carrier, the loading amounts of the main active components Cs and Al are 5 wt.% to 20 wt.% and 1 wt.% to 10 wt.% respectively, and the loading amount of the auxiliary agent is 0.1 wt.% to 5 wt.%, based on the oxide. The catalyst has good activity, selectivity and stability, simple preparation process and suitability for large-scale industrial applicationThe application is as follows.)

1. A catalyst for synthesizing methyl methacrylate by methyl propionate and formaldehyde is characterized in that: the main active components are Cs and Al, the auxiliary agent is more than one of Zr, La, Ce and Zn, and the carrier is porous SiO₂(ii) a Based on the carrier, the loading amounts of the main active components Cs and Al are respectively 5 wt.% to 20 wt.% and 1 wt.% to 10 wt.% calculated according to oxides; the loading amount of the auxiliary agent is 0.1-5 wt% calculated by oxide based on the carrier.

2. The catalyst of claim 1, wherein: the active component Cs is selected from one of cesium nitrate, cesium carbonate or cesium acetate, Al is selected from one of aluminum nitrate, aluminum sulfate or aluminum chloride, the auxiliary agents Zr, La, Ce and Zn are selected from nitrates of the active component Cs, and the carrier is SiO₂Is selected from one with the pore size of 2nm-12 nm.

3. The catalyst of claim 1, prepared by the steps of:

(1) and (3) carrier treatment: soaking and washing the carrier for 3-5 times by using deionized water, then putting the carrier into a blast drying oven, drying the carrier for 8-12 hours at the temperature of 80-120 ℃, finally putting the carrier into a muffle furnace, and roasting the carrier for 2-8 hours at the temperature of 300-500 ℃;

(2) preparing an active component aqueous solution: weighing Cs sources and Al sources with corresponding mass according to the loading capacity of the active components to prepare aqueous solution with a certain concentration;

(3) loading active components: adding the carrier obtained in the step (1) into the active component aqueous solution prepared in the step (2) by adopting an isometric impregnation method, stirring and standing for 2-24 h, and then completely drying at 60-150 ℃;

(4) a loading auxiliary agent component: preparing an auxiliary salt solution with a certain concentration, adding the catalyst precursor in the step (3) into the salt solution, stirring and standing for 2-24 h, and completely drying at 60-150 ℃;

(5) roasting the catalyst: and (3) putting the catalyst precursor loaded with the active component and the auxiliary agent obtained in the step (4) into a muffle furnace, heating at the speed of 1-15 ℃/min, roasting at the temperature of 400-600 ℃ for 4-12 h, and finally cooling to room temperature to obtain the catalyst.

4. A process for preparing a catalyst for the synthesis of methyl methacrylate from methyl propionate and formaldehyde, characterized in that the catalyst is prepared by the process according to claims 1 to 3 for use in aldol condensation reactions.

5. Use of a catalyst according to claim 1 for the synthesis of methyl methacrylate from methyl propionate and formaldehyde, characterized in that: the reaction conditions are as follows: methyl propionate/formaldehyde is 1: 2-1: 1, methanol/formaldehyde is 1: 1-2: 1, and the feeding airspeed is 0.3-1.8 h^-1The reaction temperature is 350-390 ℃.

Technical Field

The invention relates to a catalyst for preparing methyl methacrylate from methyl propionate and formaldehyde and an application method thereof, in particular to a catalyst for catalyzing methyl propionate and formaldehyde to synthesize methyl methacrylate and a preparation method thereof.

Background

Methyl methacrylate is an important polymeric monomer and chemical raw material, is commonly used for producing polymethyl methacrylate (organic glass) and acrylic resin materials, and is also widely applied to producing plastics, coatings, adhesives and various industrial auxiliaries. In recent years, the MMA industry and demand in our country have been on a substantially rapid growth trend. From 2009 to 2013, the capacity of the biomass fuel is increased from 42 ten thousand tons/year to 59 ten thousand tons/year, and the increase rate is 7 percent; the product demand is increased from 47 ten thousand tons per year to 69 ten thousand tons per year, and the composite growth rate reaches about 8 percent. By 2014-2018, the total demand of MMA has increased from 75 ten thousand tons/year to 100 ten thousand tons/year, while the production energy only increases from 59 ten thousand tons/year to 87 ten thousand tons/year, and a remarkable supply-short demand condition appears.

The traditional methyl methacrylate production process is an acetone cyanohydrin method, and a virulent raw material hydrocyanic acid is required in the reaction process, so that the environment is seriously polluted, the potential safety hazard is large, and the process is laggard. Subsequently, isobutylene oxidation (also called C4 oxidation) and ethylene routes were developed. While cleaner than the acetone cyanohydrin route process, the feedstock is heavily dependent on petroleum refining products. China has an energy structure rich in coal, lean in oil and little in gas, oil is imported for a long time, the import quantity is continuously increased, and the external dependency degree is increased year by year. Therefore, the development of a clean and efficient coal-based synthetic route is not only beneficial to relieving the supply-demand contradiction of petroleum resources in China, but also can effectively utilize coal chemical products and solve the problem of excess capacity. In recent years, a process route for preparing methyl methacrylate by using methyl propionate and formaldehyde as raw materials through a one-step aldol condensation reaction attracts great attention. The route has the advantages of cheap and wide raw materials, short process flow, simple operation and the like, and can open consumption outlets for methyl propionate and formaldehyde. Catalysts used in this reaction have also been reported to include CN 102146032A, CN 101829558, CN 102350336A, CN 102962062A, CN 104513163A, CN 102775302A, CN 106674010A, CN 109293511A, CN 109232247 a and CN 109364908 a. However, the problems of low catalyst activity, poor selectivity, easy activation and the like existing in the prior art are always the road barrows for industrial popularization.

Disclosure of Invention

Based on the problems of the catalyst, the invention aims to provide an acid-base bifunctional catalyst for synthesizing methyl methacrylate by methyl propionate and formaldehyde in one step and a preparation method thereof, so that the yield and the selectivity of the methyl methacrylate are improved, and the catalyst has better mechanical strength and carbon deposition resistance. The catalyst has high activity, good stability and simple preparation process, and is suitable for large-scale industrial production and application.

In order to achieve the purpose, the invention adopts the following technical scheme:

a catalyst for synthesizing methyl methacrylate from methyl propionate and formaldehyde in one step comprises a main active component, an auxiliary agent and a carrier. The main active components are Cs and Al, the auxiliary agent is more than one of Zr, La, Ce and Zn, and the carrier is porous silicon dioxide (SiO)₂)；

Based on the carrier, the loading amount of the main active component Cs is 5-20 wt%, and the loading amount of Al is 1-10 wt% calculated according to oxides;

the loading amount of the auxiliary agent is 0.1-5 wt% calculated by oxide based on the carrier;

cs and Al are used as main active components, and a small amount of auxiliary agent is added, so that the selectivity and the anti-carbon deposition capability of the catalyst can be improved.

The active component Cs is one of cesium nitrate, cesium acetate or cesium carbonate; the auxiliary agent is selected from nitrates of Zr, La, Ce and Zn;

the active component Al is one of aluminum nitrate, aluminum sulfate and aluminum chloride;

the carrier SiO₂Is selected from one with the pore size of 2nm-12 nm.

The acid-base bifunctional catalyst for preparing methyl methacrylate from methyl propionate and formaldehyde is prepared by the following steps:

(1) and (3) carrier treatment: soaking and washing the carrier for 3-5 times by using deionized water, then putting the carrier into a blast drying oven, drying the carrier for 8-12 hours at the temperature of 80-120 ℃, finally putting the carrier into a muffle furnace, and roasting the carrier for 2-8 hours at the temperature of 300-500 ℃;

(2) preparing an active component aqueous solution: weighing Cs sources and Al sources with corresponding mass according to the loading capacity of the active components to prepare aqueous solution with a certain concentration;

(3) loading active components: adding the carrier obtained in the step (1) into the active component aqueous solution prepared in the step (2) by adopting an isometric impregnation method, stirring and standing for 2-24 h, and then completely drying at 60-150 ℃;

(4) a loading auxiliary agent component: preparing an auxiliary salt solution with a certain concentration, adding the catalyst precursor in the step (3) into the salt solution, stirring and standing for 2-24 h, and fully drying at 60-150 ℃;

(5) roasting the catalyst: and (3) putting the catalyst precursor loaded with the active component and the auxiliary agent obtained in the step (4) into a muffle furnace, heating the precursor to 400-600 ℃ from room temperature at a heating rate of 1-15 ℃/min, roasting the precursor for 4-12 h at the temperature, and finally cooling the precursor to room temperature to obtain the catalyst.

The preparation method of the catalyst for synthesizing methyl methacrylate by methyl propionate and formaldehyde in one step has the application conditions that: methyl propionate/formaldehyde is 1: 2-1: 1, methanol/formaldehyde is 1: 1-2: 1, and the feeding airspeed is 0.3-1.8 h^-1The reaction temperature is 350-390 ℃.

Compared with the prior art, the invention has the advantages that:

(1) cs and Al are used as main active components, wherein the Cs provides an alkaline active center, and the Al provides an acidic active center. The quantity and the strength of acid-base active sites of the catalyst can be effectively regulated and controlled by changing the loading quantity of Cs and Al, so that the activity of the catalyst is improved while the better selectivity of the catalyst is ensured;

(2) the introduction of the auxiliary agent is beneficial to further improving the selectivity of the product and simultaneously enhancing the carbon deposition resistance of the catalyst;

(3) the preparation method of the catalyst is simple, short in steps, wide in raw material source, suitable for large-scale industrial application and environment-friendly.

The specific implementation mode is as follows:

the present disclosure is described in further detail below with reference to specific examples, but it should not be construed that the scope of the subject matter of the present disclosure is limited to the following examples. Various substitutions and alterations can be made without departing from the technical idea of the invention as described above, according to the common technical knowledge and conventional means in the field, and the scope of the invention is covered.

Example 1

The catalyst of the embodiment comprises 10 percent of active component Cs, 3 percent of active component Al, 0.1 percent of auxiliary agent Zr and SiO with the aperture of 2nm₂And (3) a carrier. Wherein the Cs source is cesium nitrate, the Al source is aluminum nitrate, and the Zr source is zirconium nitrate. The preparation method comprises the following steps:

(1) weighing 1.38g of cesium nitrate and 2.21g of aluminum nitrate, and dissolving in water to prepare an aqueous solution;

(2) weighing 10g of SiO₂Adding the carrier into the solution prepared in the step (1) according to an isometric impregnation method, aging at room temperature for 10h, and drying at 120 ℃ for 12 h;

(3) weighing 0.035g of zirconium nitrate, adding water to dissolve, and preparing into an aqueous solution;

(4) and (3) adding the solid obtained by drying in the step (2) into the solution prepared in the step (3) according to an isometric impregnation method, aging at room temperature for 10h, drying at 120 ℃ for 12h, and then roasting at 500 ℃ for 5h to obtain the catalyst, which is recorded as Cat-1.

Example 2:

the catalyst of the embodiment comprises 10 percent of active component Cs, 3 percent of active component Al, 0.3 percent of auxiliary agent Ce and SiO with the aperture of 6nm₂And (3) a carrier. Wherein the Cs source is cesium carbonate, the Al source is aluminum nitrate, and the Ce source is cerium nitrate. The preparation method comprises the following steps:

(1) weighing 1.16g of cesium carbonate and 2.21g of aluminum nitrate, and dissolving in water to prepare an aqueous solution;

(2) weighing 10g of SiO₂Adding the carrier to the carrier by an equal volume impregnation methodAging the solution prepared in the step (1) at room temperature for 10h, and drying at 120 ℃ for 12 h;

(3) weighing 0.076g of cerium nitrate, adding water to dissolve the cerium nitrate, and preparing an aqueous solution;

(4) and (3) adding the solid obtained by drying in the step (2) into the solution prepared in the step (3) according to an isometric impregnation method, aging at room temperature for 10h, drying at 120 ℃ for 12h, and then roasting at 500 ℃ for 5h to prepare the catalyst, which is recorded as Cat-2.

Example 3:

the catalyst of the embodiment comprises 10% of active component Cs, 3% of active component Al, 0.3% of auxiliary agent La and SiO with the aperture of 12nm₂And (3) a carrier. Wherein the Cs source is cesium acetate, the Al source is aluminum nitrate, and the La source is lanthanum nitrate. The preparation method comprises the following steps:

(1) weighing 1.36g of cesium acetate and 2.21g of aluminum nitrate, and dissolving in water to prepare an aqueous solution;

(2) weighing 10g of SiO₂Adding the carrier into the solution prepared in the step (1) according to an isometric impregnation method, aging at room temperature for 10h, and drying at 120 ℃ for 12 h;

(3) weighing 0.080g of lanthanum nitrate, adding water for dissolving, and preparing an aqueous solution;

(4) and (3) adding the solid obtained by drying in the step (2) into the solution prepared in the step (3) according to an isometric impregnation method, aging at room temperature for 10h, drying at 120 ℃ for 12h, and then roasting at 500 ℃ for 5h to prepare the catalyst, which is recorded as Cat-3.

Example 4:

the catalyst of the embodiment comprises 15 percent of active component Cs, 5 percent of active component Al, 0.2 percent of auxiliary agent Zn and SiO with the aperture of 6nm₂And (3) a carrier. Wherein the Cs source is cesium nitrate, the Al source is aluminum chloride, and the Zn source is zinc nitrate. The preparation method comprises the following steps:

(1) weighing 2.07g of cesium nitrate and 2.37g of aluminum chloride, adding water to dissolve the cesium nitrate and the aluminum chloride to prepare an aqueous solution;

(2) weighing 10g of SiO₂Adding the carrier into the solution prepared in the step (1) according to an isometric impregnation method, aging at room temperature for 10h, and drying at 120 ℃ for 12 h;

(3) weighing 0.073g of zinc nitrate, adding water to dissolve the zinc nitrate, and preparing an aqueous solution;

(4) and (3) adding the solid obtained by drying in the step (2) into the solution prepared in the step (3) according to an isometric impregnation method, aging at room temperature for 10h, drying at 120 ℃ for 12h, and then roasting at 500 ℃ for 5h to prepare the catalyst, which is recorded as Cat-4.

Example 5

The catalyst of the embodiment comprises 10 percent of active component Cs, 5 percent of active component Al, 0.3 percent of auxiliary agent Ce and SiO with the aperture of 6nm₂And (3) a carrier. Wherein the Cs source is cesium nitrate, the Al source is aluminum sulfate, and the Ce source is cerium nitrate. The preparation method comprises the following steps:

(1) weighing 1.38g of cesium nitrate and 3.27g of aluminum sulfate, adding water to dissolve, and preparing an aqueous solution;

(2) weighing 10g of SiO₂Adding the carrier into the solution prepared in the step (1) according to an isometric impregnation method, aging at room temperature for 10h, and drying at 120 ℃ for 12 h;

(3) weighing 0.076g of cerium nitrate, adding water to dissolve the cerium nitrate, and preparing an aqueous solution;

(4) and (3) adding the solid obtained by drying in the step (2) into the solution prepared in the step (3) according to an isometric impregnation method, aging at room temperature for 10h, drying at 120 ℃ for 12h, and then roasting at 500 ℃ for 5h to prepare the catalyst, which is marked as Cat-5.

Example 6

The catalyst of the embodiment comprises 10 percent of active component Cs, 3 percent of active component Al, 0.1 percent of auxiliary agent Ce and SiO with the aperture of 6nm₂And (3) a carrier. Wherein the Cs source is cesium nitrate, the Al source is aluminum nitrate, and the Ce source is cerium nitrate. The preparation method comprises the following steps:

(1) weighing 1.38g of cesium nitrate and 2.21g of aluminum nitrate, and dissolving in water to prepare an aqueous solution;

(2) weighing 10g of SiO₂Adding the carrier into the solution prepared in the step (1) according to an isometric impregnation method, aging at room temperature for 10h, and drying at 120 ℃ for 12 h;

(3) weighing 0.025g of cerium nitrate, adding water to dissolve the cerium nitrate to prepare an aqueous solution;

(4) and (3) adding the solid obtained by drying in the step (2) into the solution prepared in the step (3) according to an isometric impregnation method, aging at room temperature for 10h, drying at 120 ℃ for 12h, and then roasting at 500 ℃ for 5h to prepare the catalyst, which is recorded as Cat-6.

Catalyst evaluation example 1:

the catalyst activity test experiment is carried out on a fixed bed reactor, the catalyst loading is 6mL, the methyl propionate/formaldehyde molar ratio is 1:1, the methanol/formaldehyde molar ratio is 2:1, and the airspeed is 0.6h^-1The reaction temperature was 350 ℃ and the results are shown in Table 1:

TABLE 1

Catalyst numbering	Conversion of methyl methacrylate/%)	Methyl methacrylate selectivity/%)
			Cat-1	20.6	85.4
Cat-2	24.2	91.4
			Cat-3	22.1	86.8
Cat-4	25.3	88.9
			Cat-5	22.4	90.7
Cat-6	27.5	94.6