Mesoporous WO₃-Nb₂O₅ Catalysts Synthesized via Hard Templating for Selective Gas-Phase Dehydration of Glycerol to Acrolein

This study investigates the catalytic dehydration of glycerol to acrolein using bulk WO3 (b-WO3) and mesoporous WO3 (m-WO3) catalysts with varying molar percentages of Nb. The mesoporous catalysts were synthesized via the nanocasting method using KIT-6 as hard templates. We optimized the molar ratio of Nb (0, 0.005, 0.01, 0.02), reaction temperature (260-340 degrees C), and liquid hourly space velocity to enhance the catalytic process. Among the catalysts tested, the m-WO3-Nb2O5 (m-WNb) exhibited superior acrolein selectivity and stability compared to both m-WO3 and b-WO3. The highest acrolein selectivity of 87% at 100% glycerol conversion was achieved with the m-WNb (1:0.01) catalyst under optimal conditions: 300 degrees C, a feed rate of 14.4 mL/h, and a glycerol concentration of 10 wt %. The study also examines the role of pore diameter and other factors influencing catalyst activity. Doping Nb into m-WO3 enhanced both acrolein selectivity and structural stability, due to a significant increase in total acidity and the optimization of the Br & oslash;nsted to Lewis acid site ratio, which are critical factors in maximizing acrolein production.