Layered double hydroxide uniformly coated on mesoporous silica with tunable morphorlogies for catalytic transesterification of glycerol with dimethyl carbonate

Abstract

Layered double hydroxides (LDH) is an attractive solid base catalyst for transesterification of glycerol with dimethyl carbonate. A major challenge in enhancing the catalytic performance of LDH for this process is to overcome the internal diffusion limitations and increase the availability of basic sites. Herein we present ultrasonic and hydrothermal post-synthesis strategies in uniformly coating of LDH on mesochannels of mesoporous silica. The effects of precursors, preparation methods and morphologies on preparing LDH/SBA-15 nano-composites were investigated. Rice-shaped LDH/SBA-15 nano-composite catalysts exhibited better performance with a 78% glycerol conversion and 90% selectivity of glycerol carbonate than the catalysts with morphologies of short-rods, and long-rods. The results revealed that hierarchical nanostairs at the edge and well-ordered mesochannels stacked along the long axis direction reduced internal diffusion path lengths and increased availability of basic sites. This approach in morphology controlling synthesis of LDH based nano-composite catalysts shed light on the uniformly coating of other diatomic and triatomic metal LDH within mesochannels of mesoporous silica to fabricate novel nano-composite catalysts.