Recent developments in the field of dehydration of bio-renewable glycerol to acrolein over molecular sieve catalysts

The surplus production of glycerol as a byproduct of biodiesel has become an urgent problem for the sustainability of the biodiesel industry. The catalytic transformation of glycerol to value-added chemicals has attracted the attention of researchers worldwide over the last decade. Among them, selective dehydration of glycerol to acrolein has gained interest from both academic researchers and industrial applications. Molecular sieves have been considered as the most promising catalysts for industrial applications of glycerol dehydration. However, there is no systematic summary for the research carried out for this reaction over molecular sieve catalysts. This work provides a comprehensive and critical review of glycerol dehydration to acrolein over molecular sieve catalysts, including ZSM-5, ZSM-11, MCM-22, MCM-41, SBA-15, SAPO-34, HY and Hβ. The key technical problems that restrict its industrial application are the easy coking and poor stability of the molecular sieves. In particular, the pore size, pore structure, acid amount, acid strength, acid type and reaction conditions that influence the dehydration performance are discussed in detail. Furthermore, the reaction mechanism, reaction kinetics, reaction thermodynamics and future research directions for catalyst design and engineering are also presented. This review will deepen our understanding of the catalytic dehydration of glycerol to acrolein and provide guidance for researchers on the rational design of molecular sieve catalysts.