Preparation method for polyformaldehyde dimethyl ether adopted as alcohol-containing fuel additive

The present invention relates to a preparation method for polyformaldehyde dimethyl ether adopted as an alcohol-containing fuel additive, wherein a mixture of methanol and a paraformaldehyde dissolving liquid reacts in a reaction kettle under the effect of a catalyst. The method is characterized in that a polyferric sulfate compounding material is adopted as a catalyst, and reacts with a mixture of methanol and paraformaldehyde in a reaction kettle, a pre-dewatering treatment is performed after distillation, and deep molecular sieve dewatering is performed to produce the polyformaldehyde dimethyl ether adopted as the alcohol-containing fuel additive, such that the influence of application of the acid as the catalyst on the polyformaldehyde dimethyl ether decomposition is eliminated so as to cause the short storage time; and the water contained in the reactant and the water produced from the reaction are removed so as to reduce the water content in the product and reduce the hydrolysis production rate of the product, such that the Reid vapor pressure is reduced, the water resistance is improved, the gasoline quality is ensured, and the technical problem that the vehicle easily produces gas blocking at the high altitude area in the high temperature season is prevented.