Method for producing polyoxymethylene dimethyl ethers

A method for producing polyoxymethylene dimethyl ether, the method comprising:

• introducing:
• i) a formaldehyde source, and
• ii) at least one compound of the formula (I)
• H3C—O—R (I)
• where;
• R is H or —(CH2O)x—CH3 with x being 0 or 1
• as reactants into a reactive distillation unit;
• and
• reacting the formaldehyde source and the at least one compound of formula (I) to give polyoxymethylene dimethyl ether, wherein the method produces polyoxymethylene dimethyl ether exclusively in the reactive distillation unit;
• wherein the reactive distillation unit comprises one or more reaction zones, each containing a catalyst, and one or more distillative separation zones;
• wherein the one or more reaction zones contain a hollow body which at least partially encloses the catalyst;
• wherein gaseous reactants, which are ascending in the reactive distillation unit, are able to flow through the hollow body, but the hollow body prevents contact between the catalyst and the liquid polyoxymethylene dimethyl ether, which is running back downward to the reactive distillation unit;
• and
• wherein the liquid polyoxymethylene dimethyl ether which is running back downward in the reactive distillation unit runs at least partly laterally past the hollow body.