Preparation of polyoxymethylene dimethyl ethers by acid-activated catalytic conversion of methanol with formaldehyde formed by dehydrogenation of methanol

摘要

A particularly useful process which includes the steps of providing a feedstream comprising methanol, a soluble condensation promoting component capable of activating a heterogeneous acidic catalyst and a source of formaldehyde formed by conversion of methanol in the presence of a catalyst comprising copper and zinc; and heating this feedstream with the heterogeneous acidic catalyst in a catalytic distillation column to convert methanol and formaldehyde present to methylal and higher polyoxymethylene dimethyl ethers and to separate the methylal from the higher polyoxymethylene dimethyl ethers is disclosed. Advantageously, methylal and higher polyoxymethylene dimethyl ethers are formed and separated in a catalytic distillation column. By including within the column a section containing an anion exchange resin, an essentially acid-free product is obtained. Products can be used directly as a blending component, or fractionated, as by further distillation, to provide more suitable components for blending into fuel.