METHOD FOR PRODUCING POLYOXYMETHYLENE DIMETHYL ETHERS FROM FORMALDEHYDE AND METHANOL IN AQUEOUS SOLUTIONS

摘要

Process for the preparation of polyoxymethylene dimethyl ethers with ‰ ¥ 3 oxymethylene units (OME n = ‰ ¥ 3) comprising the steps of:(i) feeding formaldehyde, methanol and water into a reactor R and converting to a reaction mixture containing formaldehyde, water, methylene glycol, polyoxymethylene glycols, methanol, hemiformals, methylal (OME n = 1) and polyoxymethylene dimethyl ether (OME n 1);(ii) feeding the reaction mixture into a reactive distillation column K1 and separating it into a low-boiling fraction F1 comprising formaldehyde, water, methylene glycol, polyoxymethylene glycols, methanol, hemiformals, methylal (OME n = 1) and polyoxymethylene dimethyl ether having 2 to 3 oxymethylene units (OME n = 2 -3) and a high-boiling fraction F2 containing polyoxymethylene dimethyl ether with more than two oxymethylene units (OME n ‰ ¥ 3).