CN101829558B - Catalyst for directly producing methyl methacrylate by reacting methyl propionate and formaldehyde and preparation method thereof - Google Patents

Abstract

The purpose of this invention is to provide a kind of catalyst and preparation method thereof that directly produce methyl methacrylate by the reaction of methyl propionate and formaldehyde. It is characterized in that the mass ratio of the supported metal of the catalyst to the carrier is: Cs:Zr:Ce:SiO ₂ =1~10:0.005~0.5:0.001~0.1:100, and the water-soluble non-ionic surface The active agent is used as a dispersion accelerator of the active component on the surface of the carrier, and the dispersion degree of the active component Cs on the surface of the carrier can be improved by changing the concentration or type of the dispersion accelerator, thereby improving the catalytic performance of the catalyst.

Description

Catalyst for directly producing methyl methacrylate by reacting methyl propionate and formaldehyde and preparation method thereof

Technical field:

The invention belongs to the technical field of catalysis, and in particular relates to a catalyst for directly preparing methyl methacrylate by reacting methyl propionate and formaldehyde and a preparation method thereof.

Background technique:

Methyl methacrylate (MMA) is an important organic chemical raw material. It is a monomer for the production of polymethyl methacrylate (organic glass) and acrylic resin materials. It is also widely used in coatings, textiles, papermaking, leather, rubber, etc. Different fields such as adhesives and medical functional polymer materials.

In the presence of a metal catalyst, the reaction of methyl propionate and formaldehyde to generate methyl methacrylate has been involved in a number of patents, such as Lucite and Ineos Acrylics UK Ltd, which use Cs as the main active component and add B, Mg, SiO ₂ supported catalysts with additives such as Al, Zr, Ha, Ti, Fe, etc., see US6476255, US6544924, US7053147, EP1243330A1, CN99805643 and other patents. Mamoru Ai studied the loading of different alkali metals (Na, K, Rb, Cs) and alkaline earth metals (Mg, Ca, Ba) on different types of supports (SiO ₂ , SiO ₂ -Al ₂ O ₃ , Zeolite 13X, SiC, Active carbon , Ca(OH) ₂ ), the catalytic properties of the catalysts were investigated, and the influence of different catalyst compositions on the reaction of methyl propionate and formaldehyde to form methyl methacrylate was investigated. The results show that the catalytic effect of the catalyst is the best when _SiO2 is used as the carrier to load the active components.

The catalysts reported above are mainly prepared by the impregnation method. As a catalyst preparation method widely used in the industry, the impregnation method is to infiltrate the active component (including the co-catalyst) into the inner surface of the porous carrier in the form of a salt solution. After fully impregnated, remove the remaining liquid, and then perform drying and roasting process to obtain a supported catalyst. The advantage of the impregnation method to prepare the catalyst is that the active components are only distributed on the surface of the carrier, the dosage is small, the utilization rate is high, and the cost is low. For the Cs-supported catalyst that directly produces methyl methacrylate by the reaction of methyl propionate and formaldehyde, the basic center is the main active center of the catalyst, and the uniform distribution of the basic center can show the best catalytic performance, which requires During the impregnation preparation process, the active components are uniformly deposited on the surface of the carrier, thereby obtaining a highly dispersed supported catalyst.

Contents of the invention

The purpose of this invention is to provide a kind of catalyst and preparation method thereof that directly produce methyl methacrylate by the reaction of methyl propionate and formaldehyde. It is characterized in that the mass ratio of the supported metal of the catalyst to the carrier is: Cs:Zr:Ce:SiO ₂ =1-10:0.005-0.5:0.001-0.1:100, and a certain amount of water-soluble non-ionic The type surfactant is used as a dispersion accelerator of the active component on the surface of the carrier, and the dispersion degree of the active component Cs on the surface of the carrier can be improved by changing the concentration or type of the dispersion accelerator, thereby improving the catalytic performance of the catalyst.

Catalyst preparation method of the present invention specifically comprises the steps:

(1) take zirconium nitrate and cerium nitrate by mass ratio Zr: Ce=0.005～0.5: 0.001～0.1, be mixed with the aqueous solution that zirconium, cerium total ion molar concentration are 0.001mol/L～0.1mol/L;

(2) Under continuous stirring and at 30-80°C, weigh SiO ₂ according to the mass ratio Zr:SiO ₂ =0.005-0.5:100, mix it with the solution prepared in (1), and soak it for 5-24 hours at 100-150°C Drying without roasting or roasting at 400-500°C for 1-6 hours;

(3) Weigh cesium carbonate or cesium nitrate by mass ratio Cs:SiO ₂ =1～10:100, and prepare an aqueous solution whose molar concentration of cesium ions is 0.05mol/L～5mol/L;

(4) According to 0.02% to 2% of the mass fraction of the solution, add a dispersion accelerator to the solution prepared in (3), stir evenly, and mix thoroughly;

(5) Mix the solution prepared in (4) with the solid prepared in (2) under continuous stirring at 30-80°C, impregnate for 5-24 hours, dry at 100-150°C, and roast at 400-500°C for 2-6 hours, That is the catalyst.

The dispersion accelerator selected in the present invention is one or more of water-soluble nonionic surfactants Tween, OP, PEG200, PEG400, and PEG600.

Using the catalyst prepared by the present invention can catalyze the reaction of methyl propionate and formaldehyde to directly produce methyl methacrylate, and the reaction formula is as follows:

CH ₃ CH ₂ COOCH ₃ +HCHO→CH ₂ =C(CH ₃ )COOCH ₃ +H ₂ O

The reaction is generally carried out at elevated temperature, usually in the range of 250-400°C. In order for the reaction to form more esters, the reaction is generally carried out in the presence of the relevant alcohol, such as methanol.

Compared with the prior art, the present invention has the following advantages: a non-ionic surfactant is added as a dispersion accelerator during the impregnation preparation process of the catalyst, and the addition of the dispersion accelerator plays a certain role in the impregnation process of the active metal Cs on the carrier. The guiding effect of the catalyst can optimize the dispersion of the active components on the carrier, thereby improving the catalytic performance of the catalyst.

Detailed ways

The present invention is illustrated by the following examples, but the present invention is not limited to the following examples. Without departing from the purpose described before and after, all variant embodiments are included in the technical scope of the present invention.

Example 1

(1) Dissolve 0.015g of Zr(NO ₃ ) ₄ ·5H ₂ O and 0.004g of Ce(NO ₃ ) ₃ ·6H ₂ O in 20.0ml of deionized water;

(2) Weigh 20.0g of SiO ₂ carrier, mix the solution in (1) with SiO ₂ carrier under continuous stirring at 40°C, soak for 8h, dry at 110°C for 2h, and roast at 450°C for 3h to obtain Zr-Ce/ _SiO2 ;

(3) Weigh 0.982g Cs ₂ CO ₃ and dissolve it in 20ml deionized water; weigh 0.051g PEG200, add it to the above cesium carbonate aqueous solution, stir evenly, and mix thoroughly;

(4) Mix the mixed solution obtained in (3) with the Zr-Ce/ _SiO2 obtained in (2) under continuous stirring at 40°C, after impregnation for 8h, dry at 110°C for 2h, and calcined at 450°C for 3h to obtain Cs - Zr-Ce/ _SiO2 catalyst.

Example 2

Catalyst composition according to Example 1, in step (3), the quality of PEG200 is 0.102g respectively.

Example 3

Catalyst preparation According to Example 1, 1.175 g of CsNO ₃ was used to replace Cs ₂ CO ₃ in step (3).

Example 4

Catalyst preparation According to Example 2, 1.175 g of CsNO ₃ was used to replace Cs ₂ CO ₃ in step (3).

The catalytic performance test of the catalyst is carried out on a fixed-bed micro-reaction device, and formaldehyde uses formaldehyde aqueous solution, the feed amount molar ratio methyl propionate: formaldehyde: methyl alcohol=1: 0.2: methanol=1: 0.2: methanol=1: 0.2: 1.3, with flow 35ml/min N ₂ is dilution gas, After drying the catalyst at 300 °C for 30 min, the mixture of reactants was passed over the catalyst with _N2 . After the feed stabilized, the reactor temperature was raised to 350 °C, and the catalyst activity and selectivity were analyzed online by GC.

Table 1 Catalyst evaluation results

Claims (1)

1. directly produce methyl methacrylate Preparation of catalysts method by methyl propionate and formolite reaction for one kind, it is characterized in that the carried metal of catalyst and the mass ratio of carrier are: Cs: Zr: Ce: SiO ₂=1～10: 0.005～0.5: 0.001～0.1: 100; Said methyl methacrylate Preparation of catalysts method comprises the steps:

(1) takes by weighing zirconium nitrate and cerous nitrate by mass ratio Zr: Ce=0.005～0.5: 0.001～0.1, the aqueous solution that to be mixed with zirconium, the total ion molar concentration of cerium be 0.001mol/L～0.1mol/L;

(2) under continuous stirring and 30～80 ℃, press mass ratio Zr: SiO ₂=0.005～0.5: 100 take by weighing SiO ₂, mix with (1) prepared solution, behind dipping 5～24h, 100～150 ℃ of dryings, not roasting or in 400～500 ℃ of roasting 1～6h;

(3) press mass ratio Cs: SiO ₂Take by weighing cesium carbonate or cesium nitrate at=1～10: 100, is mixed with the aqueous solution that the cesium ion molar concentration is 0.05mol/L～5mol/L;

(4) according to 0.02%～2% of liquid quality fraction; In (3) prepared solution among the water miscible nonionic surface active agent Tween of adding, OP, PEG200, PEG400, the PEG600 one or more are as disperseing promoter; Stir, fully mix;

(5) down (4) prepared solution is mixed with (2) prepared solid continuous stirring and 30～80 ℃, flood 5～24h after, 100～150 ℃ of dryings in 400～500 ℃ of roasting 2～6h, promptly get catalyst.