Water assisted formaldehyde-containing chemicals refining with easily separable methanol over Cu/ZnO/Al2O3 catalyst

Abstract

A green protocol for refining industrial chemicals containing formaldehyde (FA) impurities is presented here for the first time. FA, as an unreactant or a byproduct, causes separation problems in many industrial processes. It can be removed to a level of less than 1 ppm with easily separable methanol formation using commercial Cu/ZnO/Al2O3 catalyst at atmospheric pressure in the absence of external hydrogen. The formation of methanol is achieved by the transfer of hydrogen species generated with the assistance of water to free FA, affording high methanol selectivity (62 %). By investigating potential intermediates and implementing deuterium labeling experiments, together with carbon and hydrogen balance calculations, a plausible pathway of water-assisted FA removal is proposed. Moreover, the in situ generated hydrogen species can be transferred directly into unsaturated compounds for selective reduction.