Catalytic dehydration of glycerol to acrolein over HPW supported on Cs+ modified SBA-15

• 50HPW/Cs-SBA gave 85% of acrolein yield in glycerol dehydration.
• Active sites are medium acid sites of HPW dispersed on Cs+ modified SBA-15.
• Acrolein yield was correlated with fraction of medium acid sites.
• Catalyst activity was completely recovered after coke burning regeneration.

The sustainable production of acrolein from glycerol dehydration is a competitive alternative to the propylene-based technology. A new catalyst, H3PW12O40 supported on Cs+ modified SBA-15 (HPW/Cs-SBA), was prepared and tested for glycerol dehydration. The catalysts were characterized using N2 adsorption–desorption, X-ray diffraction, Fourier-transform infrared spectroscopy, NH3 temperature-programmed desorption, and thermogravimetric analysis. The dispersion of Keggin anion on the support was improved by grafting Cs+ onto the silica surface followed by partial neutralization of H3PW12O40 (HPW) with Cs+ to form Cs2.5H0.5PW12O40 (CsPW). Good activity and selectivity for dehydration of glycerol to acrolein were obtained by converting the strong acid sites of HPW to selective medium acid sites. The best catalyst, with 50% of HPW loading (denoted as 50HPW/Cs-SBA), had the largest fraction of medium acid sites (71%) and gave 85% of acrolein yield at 300 °C with co-feeding of O2. The stability of 50HPW/Cs-SBA was significantly improved, with acrolein yield retained above 85% after 150 h of reaction. In addition, this catalyst had a good thermal stability at coke burning temperature of 500 °C. The yield of acrolein was correlated with the fraction of medium acid sites on the catalysts.

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