Selective vapour-phase dehydrocyclization of biomass-derived 1,4-butanediol to γ-butyrolactone over Cu/ZnAl2O4-CeO2 catalyst

Production of γ-butyrolactone (GBL) from vapour-phase dehydrocyclization of biomass derived 1,4-butanediol is considered as more sustainable and significantly commercial industrial process. In this regards, Cu-based catalyst was designed with ZnAl2O4 spinel support and CeO2 as a promoter to obtain Cu/ZnAl2O4-CeO2 catalyst with different Cu:Ce mass ratio. The catalysts were characterized by XRD, H2-TPR, FT-IR, CO2-TPD, FE-SEM and BET analysis and then tested for the production of γ-butyrolactone (GBL) by dehydrocyclization of 1,4-butanediol (BDO). Further, various reaction parameters were optimized and their effects on the catalytic activity were studied to obtain maximum yield towards desired product at ambient reaction conditions. The results revealed that metallic Cu species and CeO2 as a promoter were highly dispersed on ZnAl2O4 support with appreciable surface area. Additionally, CeO2 as a promoter prevented agglomeration, increased the basic character of catalyst to selectively obtain GBL as a major product. 10 wt% Cu/ZnAl2O4-10 wt% CeO2 catalyst exhibited excellent yield (94%) towards GBL product with tetrahydrofuran (THF) as the only by-product and demonstrated consistent activity and selectivity during 26 h time on stream. Further, the optimized catalyst displayed appreciable recyclability performance up to seven recycles without much loss in its catalytic performance making the catalyst feasible at industrial scale.