Method for preparing methyl methacrylate through aldol condensation of methyl propionate and formaldehyde

The invention provides a method for preparing methyl methacrylate through aldol condensation of methyl propionate and formaldehyde, and belongs to the technical field of synthesis of methyl methacrylate. According to the method, methyl propionate, a formaldehyde source, methanol, water and oxygen-containing fluidized gas enter a fluidized bed reactor after pre-heating, and the oxygen in the oxygen-containing fluidized gas reacts with the carbon deposit on the surface of a catalyst so as to be consumed, such that an upper poor-oxygen zone and a lower oxygen-containing zone are formed; in the upper poor-oxygen zone, the methyl propionate reacts with the formaldehyde to form MMA, and carbon deposit is formed on the surface of the catalyst; in the lower oxygen-containing zone, the catalyst contacts the oxygen to burn off the carbon deposit on the surface; the catalyst continuously and cyclically flows in the fluidized bed; and the catalyst regenerated in the lower oxygen-containing zone cyclically returns to the