Enhanced Propane Dehydroaromatization over CeZn/ZSM-5 Nanosheets

Abstract Propane dehydroaromatization (PDA) provides an efficient nonpetroleum route for upgrading light alkanes into high-value aromatics, yet conventional Zn-modified ZSM-5 (Zn/n-HZSM-5) catalysts suffer from rapid deactivation owing to diffusion limitations and subsequent carbon deposition. Herein, we developed a catalyst with a shortened b-axis (Zn/s-HZSM-5) via a urea-assisted hydrothermal method to optimize mass transfer within the zeolite channels. Compared with the Zn/n-HZSM-5 possessing a prolonged b-axis thickness of 250–270 nm, the Zn/s-HZSM-5 catalyst exhibited a significantly thinner b-axis of 100–130 nm, leading to a dramatic enhancement in propane conversion from 39.5% to 89.1%. Zero-length column (ZLC) desorption, fixed-bed breakthrough, and transient propane/N2 switching experiments demonstrated that the shortened b-axis pathways accelerated the diffusion of heavy aromatics, thereby reducing their residence time within the micropores. Ultraviolet Raman (UV-Raman) and thermogravimetric (TG) analyses revealed that Zn/s-HZSM-5 suppresses graphitic coke formation, which was responsible for irreversible pore-mouth blocking. To improve the regeneration durability of the catalyst, a trace amount of Ce was incorporated (0.10CeZn/s-HZSM-5), giving an aromatics yield exceeding 50% after three consecutive reaction–regeneration cycles (560 °C, WHSV at 0.8 h–1 and N2/C3H8 at 1.5 vol/vol). This work indicates that managing diffusion kinetics via b-axis manipulation is a key strategy for achieving sustained longevity in alkane upgrading.