Method for preparing MMA (methyl methacrylate) by coal-based route C2 method

The invention discloses a method for preparing MMA (methyl methacrylate) by a coal-based route C2 method, and particularly relates to the field of MMA preparation, which comprises the following steps: mixing a methanol solution of formaldehyde and propionaldehyde according to a molar ratio of 1: 1, and carrying out thermal condensation reaction under the catalytic action of a catalyst to obtain a mixed product containing a water phase and an oil phase; performing oil-water separation on the mixed product to obtain an oil phase which comprises a methanol-MAL mixed solution; methanol is taken additionally, the methanol and the methanol-MAL mixed solution are subjected to an oxidative esterification reaction according to the molar ratio of (3-10): 1, and an MMA crude product is obtained; according to the method, a conventional aqueous solution of formaldehyde is adjusted into a methanol solution of formaldehyde, azeotropy and boiling point temperature difference of methanol and MAL can be effectively separated t