Acid-driven architecture via HZSM-5 zeolite doping La & P for improving ethylene production in catalytic cracking of n-octane and diesel

La/P/HZSM-5 with multi-level pore structure was synthesized via a stepwise dual-template strategy. • The La/P/HZSM-5 zeolite reduces Brønsted acidity and creates Lewis acidity. • The optimal acidity of La/P/HZSM-5 promotes radical and monomolecular cracking. The enhancement of ethylene yield via catalytic cracking presents a persistent challenge in addressing ethylene supply shortages. A series of bifunctional catalysts (La/P/HZSM-5) were prepared via simultaneous incorporation of lanthanum and phosphorus into HZSM-5 zeolite. The Py-IR analyses revealed that the simultaneous introduction of lanthanum and phosphorus resulted in a decrease in the Brønsted acid content of the La/P/HZSM-5 catalyst from the HZSM-5 (0.792 mmol/g) to 0.223 mmol/g. Further analysis of the structure-activity relationship between the catalyst and its performance reveals that the low Brønsted acid and porous structure effectively promotes the monomolecular decomposition of the cracking process. It was evident that the synergistic modification has resulted in the La/P/HZSM-5 catalyst demonstrating superior performance in n -octane cracking, with a cracking mechanism ratio (CMR) of 49.35. The balanced metal-acid functionality of the La/P/HZSM-5 catalyst was found to result in C 2 H 4 yields of 31.23% from n -octane and 19.18% from diesel, representing increases of 31.11% and 50.20%, respectively, compared to the parent HZSM-5 (23.82% and 12.77%). The present work provided a theoretical foundation for the design of metal-acid bifunctional catalysts, with a view to improving ethylene production in catalytic cracking processes. Download: Download high-res image (260KB) Download: Download full-size image