Vapour phase dehydration of glycerol to acrolein over NbOPO4 catalysts

Abstract

BACKGROUND: The valorization of glycerol obtained from biodiesel production is a challenging task. Effective use or conversion of crude glycerol to specific products will further reduce the cost of biodiesel production. RESULTS: Vapour phase dehydration of glycerol to acrolein was investigated over solid acid catalysts containing nio-biumoxophosphate (NbP) by varying the calcination temperature. All the catalysts prepared were active for the synthesis of acrolein (conversion of glycerol was observed in the range 75-100% with selectivity to acrolein in the range 69-86%). The acidic properties are correlated with catalytic functionalities during dehydration of glycerol. CONCLUSIONS: The NbP catalyst calcined at 550 °C has shown higher selectivity to acrolein with total conversion of glycerol. Calcination of the samples at 350 to 650 °C produces amorphous NbP sample, which contains significantly higher fractions of moderate acid sites than the crystalline NbP. The higher activity during glycerol dehydration and acrolein selectivity exhibited by NbP-550 catalyst is attributed to the presence of only moderate acidic sites with the majority of them Brønsted acidic sites.