Highly efficient and selective one-step production of glycidol from glycerol using Cs/zeolite catalysts in a packed-bed reactor

In this work, the one-step gas-phase conversion of glycerol to glycidol was achieved and optimized over CsNO 3 -modified ZSM-5 zeolite catalysts (SiO 2 /Al 2 O 3 = 1500) with varying Cs loadings (5-30 wt.%) in a packed-bed reactor. To the best of our knowledge, our group’s work remains the only study of its kind reported in the literature. Increasing the reaction temperature from 350 to 450 °C enhanced both catalytic activity and glycidol selectivity, whereas further temperature elevation led to a decline in both selectivity and space-time yield (STY). The highest glycidol selectivity of 74.0 C% was achieved over the granulated 15Cs/ZSM-5 catalyst at 350 °C after 8 h of time-on-stream (TOS) using a 10 wt.% glycerol feed. A maximum glycidol yield of 61.1 C% and the highest STY of 2.5 mmol·g cat ⁻¹·h⁻¹ were achieved at glycerol concentrations of 20 and 40 wt.%, respectively. The superior performance of the 15Cs/ZSM-5 catalyst is attributed to its favorable morphology (enhanced pore diameter), high basicity, and selective dehydrative-epoxidation activity, likely facilitated by Cs-induced modification of the zeolite surface and local restructuring at the pore entrances. Although glycerol conversion gradually decreased during long-term testing, glycidol selectivity remained relatively stable over 70 h of continuous operation. Overall, this study demonstrates the development of a high-performing, regenerable catalyst with strong industrial application potential and provides mechanistic insights into the design of effective systems for the one-step synthesis of glycidol from glycerol. • One-step gas-phase glycerol to glycidol conversion achieved at ambient pressure. • 15Cs/ZSM-5 showed 74.0 C% glycidol selectivity at 350 °C after 8 h TOS. • Max glycidol yield of 61.1 C% achieved at 20 wt.% glycerol concentration. • Highest STY of 2.5 mmol·gcat⁻¹·h⁻¹ obtained at 40 wt.% glycerol concentration. • Catalyst performance stable over 70 h despite progressive deactivation.