Efficiency of zeolite MCM-22 with different SiO2/Al2O3 molar ratios in gas phase glycerol dehydration to acrolein

• MCM-22 zeolite is a highly active and selective catalyst in the gas phase dehydration of glycerol to acrolein.
• Glycerol conversion and acrolein selectivity is strongly dependent on the SiO2/Al2O3 molar ratio.
• MCM-22 (SiO2/Al2O3 = 30) has shown the best conversion and selectivity.
• Acid and textural properties role an important play in understanding catalytic performance of this zeolite.
• MCM-22 catalysts deactivate by coke formation, but can be regenerated by burning in oxidative atmosphere.

The gas-phase dehydration of glycerol was conducted over MCM-22 zeolite with different SiO2/Al2O3 molar ratios. MCM-22 zeolites were synthesized and characterized by XRD, FTIR, TG, SEM, EDX, textural analysis by N2 physisorption and NH3-TPD. The MCM-22 zeolites have presented good crystallinity, high surface areas and a decreased amount of acid sites and strength with increasing SiO2/Al2O3 ratio was observed. The glycerol conversion and acrolein selectivity increased with increasing reaction temperature from 280 °C to 320 °C on MCM-22 (30) catalyst. As long as the concentration of glycerol solution was in the range from 10% to 36.6%, there was no noticeable difference in the glycerol conversion but the acrolein yield increased with water amount in the feed. The glycerol conversion and selectivity to acrolein at 320 °C using glycerol feed of 36.6% during 10 h of reaction decreased in the following order: MCM-22 (30) > MCM-22 (50) > MCM-22 (80). This result shows that glycerol dehydration to acrolein is strongly dependent on the acid sites density and external surface area of the zeolite MCM-22.

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