One-pot oxydehydration of glycerol to value-added compounds over metal-doped SiW/HZSM-5 catalysts: Effect of metal type and loading

• Glycerol conversion to acrylic acid is done over metal-doped supported SiW catalysts.
• V-SiW/HZSM-5 exhibits the highest glycerol conversion and acrylic acid yield.
• Rate of glycerol conversion is explained by a pseudo-first order reaction.
• The Eley–Rideal model provides the best fit with the experimental results.

A one-pot oxydehydration of glycerol to value-added compounds was carried out over metal-doped SiW/HZSM-5 catalyst at low temperature (90 °C) and ambient pressure. Effects of metal types (Co, Ce, Ni and V) and loadings (0–8 wt.%) on catalyst properties and catalytic activity were explored. Doping different types of metal and loading on the surface of SiW/HZSM-5 catalyst affected surface chemistry and textural chemistry as well as the catalytic activity for glycerol conversion and product yield distribution. The V at 6% loading most effectively enhanced the activity of SiW/HZSM-5 for a one-pot oxydehydration of glycerol to value-added compounds. The presence of V6-SiW/HZSM-5 catalyst can enhance the glycerol conversion up to 99.67% with the yields of glycolic acid, formic acid, acetic acid, acrolein, acrylic acid, and propionic acid of 19.45%, 12.03%, 23.62%, 0.25%, 36.23% and 7.06%, respectively with less than 1.5% of glycerol converting to some undesired products. The kinetic studies of a one-pot oxydehydration of glycerol over this catalyst (V6-SiW/HZSM-5) showed the rate of glycerol conversion depended upon the glycerol concentration according to the pseudo-first order kinetic rate and about the zero order with respect to the H2O2 concentration. The Eley–Rideal model, assuming the reaction between a non-dissociative adsorption of H2O2 and glycerol molecule provided the best fit with the experimental results.