Catalytic self-etherification of 5-hydroxymethylfurfural to 5,5′(oxy-bis(methylene))bis-2-furfural over zeolite catalysts: effect of pore structure and acidity

The self-etherification of 5-hydroxymethylfurfural (HMF) to 5,5′(oxy-bis(methylene))bis-2-furfural (OBMF) was investigated on ZSM-5, MCM-22, beta and hierarchical micro–mesoporous ZSM-5 (HMZ) catalysts. The hierarchically structured zeolites exhibited a superior intrinsic activity and good resistance to carbonaceous deposit; the latter could be ascribed to the lower mass transfer barrier in the mesopores of the HMZ catalysts. The structure–activity correlation showed that the catalytic activity mainly originated from one or several specific Brønsted acid sites, providing key clues to design efficient zeolite catalysts for producing OBMF.