Preparation method for 1,3 butadiene

The invention provides a preparation method for 1,3-butadiene. According to the method, a zeolite molecular sieve is used as a catalyst, propylene and formaldehyde are used as raw materials, and 1,3-butadiene is continuously prepared in a fixed bed reactor; propylene and formaldehyde undergo contact reaction with the catalyst at the same time and produce 1,3-butadiene at a temperature of 150 to 400 DEG C under a pressure of 0.1 to 1.0 MPa. The method is simple, reaction conditions are mild, formaldehyde conversion per pass is as high as more than 95%, and the catalyst has high activity and is renewable and reusable.