Preparation of polyoxymethylene dimethyl ethers by catalytic conversion of formaldehyde formed by oxy-dehydrogenation of dimethyl ether

A process for oxidative dehydrogenation of dimethyl ether to form a source of formaldehyde by a process comprising continuously contacting a gaseous feedstream comprising dimethyl ether, dioxygen, dinitrogen and steam, with a catalytically effective amount of an oxidative dehydrogenation promoting catalyst comprising silver as an essential catalyst component at elevated temperatures thereby forming a gaseous mixture comprising formaldehyde, methanol, dioxygen, diluent gas, carbon dioxide and water vapor;

• cooling the gaseous dehydrogenation mixture with a liquid to take up and hold formaldehyde therein;
• and separating the resulting liquid source of formaldehyde from a mixture of gases comprising dioxygen, diluent, carbon monoxide, carbon dioxide and water vapor, wherein the ratio of dioxygen to total ether and, if present, alkanol in the gaseous feedstream is in a range from 1:1 to 1:100 moles.

A process for oxidative dehydrogenation of dimethyl ether to form a source of formaldehyde by a process comprising continuously contacting a gaseous feedstream comprising dimethyl ether, methanol, dioxygen, dinitrogen and steam, with a catalytically effective amount of an oxidative dehydrogenation promoting catalyst comprising silver as an essential catalyst component at temperatures in a range from about 550° to about 750° C. thereby forming a gaseous mixture comprising formaldehyde, methanol, dioxygen, diluent gas, carbon dioxide and water vapor, cooling the gaseous dehydrogenation mixture with a liquid to take up and hold formaldehyde therein;

• and separating the resulting liquid source of formaldehyde from a mixture of gases comprising dioxygen, diluent, carbon monoxide, carbon dioxide and water vapor, wherein the ratio of dioxygen to total ether and methanol in the gaseous feedstream is in a range from 1:1 to 1:10 moles.