Liquid Phase Oxydehydration of Glycerol to Acrylic Acid over Supported Silicotungstic Acid Catalyst: Influence of Reaction Parameters

The liquid phase catalytic oxydehydration of glycerol to acrylic acid over supported silicotungstic acid (SiW) catalysts was carried out in the batch reactor. The effect of oxidizing agent concentration (H2O2), reaction temperatures (70 and 90 °C), types of supports (HZSM-5, SiO2 and Al2O3) and SiW loading (20-60 wt.% based on support) on the conversion and product yield were investigated. The addition of H2O2 and supported SiW catalysts significantly conducted the synergetic positive effects on glycerol conversion and acrylic acid yields as well as other desired products including glycolic acid, formic acid, acetic acid, acrolein and acrylic acid. High reaction temperature was able to enhance high glycerol conversion as the same yield of all desired products. The BET surface area of supported SiW catalysts played much more important role in the activities of oxydehydration of glycerol that this oxydehydration was more remarkable than the acidity of catalysts. Among all supported SiW catalysts, the SiW/HZSM-5 with SiW loading of 30 wt.% exhibited the highest glycerol conversion (85.54%) with the production acrylic acid yield of 30.57 % over 2.74 M H2O2 at 90 °C. The kinetics of glycerol conversion to desired products over supported SiW catalyst was explored.