Method for preparing methylacrolein

Abstract

The invention relates to a method for preparing methylacrolein. In the method, Pickering emulsion is adopted as a catalyst for catalyzing a reaction of formaldehyde and propionaldehyde to prepare themethylacrolein, and the reaction process is performed in a fixed bed reactor, so that a product is separated from active ingredients of the catalyst in real time in the preparation process, and continuous operation of the preparation process is achieved; in addition, the Pickering emulsion is adopted as the catalyst for catalyzing the reaction of formaldehyde and propionaldehyde to prepare the methylacrolein, so that the contact area of a mobile phase reactant and aqueous phase catalytic active ingredients is enlarged, the highest average catalytic conversion rate of the propionaldehyde can reach 100%, and the highest yield of the methylacrolein can reach 90%.

Description

technical field [0001] The invention relates to the field of aldol condensation catalysis, and further relates to a method for preparing methacrolein. Background technique [0002] Methacrolein, also known as methacrolein, has active conjugated double bonds, and can be used to synthesize copolymers, resins and thermoplastics, and can also be used to produce fine chemical products such as methacrylic acid, methyl methacrylate, and fenpropimorph. At present, there are multiple industrial synthesis routes of methacrolein, which are divided into isobutylene oxidation method, alcohol oxidation method, formaldehyde and propionaldehyde condensation method according to raw materials. Among them, the formaldehyde and propionaldehyde condensation method has broad application prospects because of its cheap and easy-to-obtain raw materials and mild reaction conditions. [0003] There are two reaction pathways for the condensation of formaldehyde and propionaldehyde to prepare methacrol...

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Problems solved by technology

[0004] CN104311403A discloses a method in which formaldehyde organic solution and propionaldehyde are condensed under the action of ionic liquid to form methacrolein. After the reaction, the feed liquid needs to be rectified to separate methacrolein, and the dehydrated ionic liquid is recycled. In the preparation process of the method described in the scheme, there are problems of inability to operate continuously and low utilization rate of the catalyst

[0005] CN104557490A discloses a process for synthesizing methacrolein from paraformaldehyde and propionaldehyde under the action of morpholine hydrochloride. The product is obtained through distillation and static stratification. However, the preparation process cannot be continuously operated in this scheme. , it is necessary to carry out the separation operation of the active component and the product, which increases the cost of production

[0006] CN102659542A discloses a method for preparing methacrolein by catalyzing the condensation of formaldehyde and propionaldehyde with ionic liquid. The method comprises the following steps: under the catalysis of ionic liquid, the water content in the reaction system is 1-60%, and the formaldehyde and propionaldehyde are in React at 0-90°C for 0.1-180min to prepare methacrolein. The method described in this scheme has the disadvantage that the preparation process is a batch operation, the preparation process is complicated and the cost is high

[0007] Although the above-mentioned documents provide some methods for preparing methacrolein, no matter it is direct aldol condensation or Mannich reaction, the preparation process is an intermittent process, and the liquid phase system in the reaction needs high-speed stirring to increase the contact between the reactant and the catalyst After the reaction, certain means are needed to separate the product from the catalyst, the operation steps are complex and the utilization rate of the catalyst is low, so it is still of great significance to develop a method for the preparation of methacrolein that can be operated continuously

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