Vapor-phase dehydration of 1,2-propanediol to allyl alcohol over silica-supported cesium phosphate

SiO 2 -supported cesium phosphate (Cs x P/SiO 2 , x = molar ratio of Cs/P) catalysts show promising catalytic performance for the vapor-phase transformation of 1,2-propanediol (1,2-PDO) to allyl alcohol (AAL). The formation of AAL proceeded via propylene oxide (PO) formation. Simultaneously, 1,2-PDO was also converted to propanal (PAL). The Cs/SiO 2 without P mainly generated PO, and introducing P into Cs/SiO 2 promoted the consecutive transformation of PO to AAL with the concurrent reduction of PAL selectivity. Several reaction parameters, such as reaction temperature, contact time, and the phosphate content influenced the catalytic activity and product distribution. A Cs 1.4 P/SiO 2 catalyst with a phosphate content of 20 wt% exhibited 100% 1,2-PDO conversion with the AAL selectivity of 77% at 400 °C and a contact time of 1.67 h. The poisoning experiment using probe molecules reveals that basic sites are essential for the PO formation, while acid-base sites are important in the isomerization of PO to AAL. • Silica-supported cesium phosphate was active for the dehydration of 1,2-propanediol. • The introduction of Cs into the phosphate catalyst increases its basicity. • The phosphate catalyst with the Cs/P ratio of 1.4 was the most efficient. • The highest yield of allyl alcohol is 77% under optimum conditions. • Allyl alcohol formation proceeds via an acid-base concerted mechanism.