Direct conversion of glycerol to acrylic acid via integrated dehydration-oxidation bed system

Abstract

Acrylic acid can be successfully produced in a single reactor via subsequent oxidation of the glycerol-dehydrated products. Selective dehydration of glycerol to acrolein was studied at 275-400 °C over HZSM-5, HBeta, HMordenite and HY. The V-Mo oxides (15-70 mol%V) on silicic acid support (20-100 wt% mixed oxides loading) were then included as a second bed for subsequent oxidation of the dehydrated products. Over the acid zeolites, acrolein and acetol are mainly generated, together with acetaldehyde, propionaldehyde, pyruvaldehyde and other oxygenates as secondary products. A complete conversion of glycerol with high selectivity to acrolein (up to 81 mol%) can be obtained when medium pore zeolites (HZSM-5) and low glycerol concentration (10-30 wt%) was used at 300 °C. A separated-sequential bed system provides high selectivity for acrylic acid with small amount of acetic acid and acetaldehyde (∼15 mol%). The catalyst with high V content promotes total oxidation of the dehydrated products to CO while that with highly dispersed V-Mo-O phases affords 98% selectivity to acrylic acid with 48% acrolein conversion. © 2011 Elsevier B.V.