Effects of synthesis route on the performance of mesoporous ceria-alumina and ceria-zirconia-alumina supported nickel catalysts in steam and autothermal reforming of diesel

Abstract

Decline in catalyst performance due to coke deposition is the main problem in diesel steam (SR) and autothermal reforming (ATR) reactions. Good redox potential and strong interaction of CeO2 with nickel increase activity and coke resistivity of Ni/Al2O3 catalysts. In this study, mesoporous Al2O3, CeO2/Al2O3, and CeO2/ZrO2/Al2O3 supported nickel catalysts were successfully synthesized. The highest hydrogen yield, 97.7%, and almost no coke deposition were observed with CeO2/ZrO2/Al2O3 catalyst (Ni@8CeO2-2ZrO2-Al2O3-EISA) in SR reaction. The second highest hydrogen yield, 91.4%, was obtained with CeO2/Al2O3 catalyst (Ni@10CeO2-Al2O3-EISA) with 0.3 wt% coke deposition. Presence of ZrO2 prevented the transformation of cubic CeO2 into CeAlO3, which enhanced water gas shift reaction (WGSR) activity. Ni@10CeO2-Al2O3-EISA did not show any decline in activity in a long-term performance test. Higher CeO2 incorporation (20 wt%) caused lower steam reforming activity. Change of synthesis route from one-pot to impregnation for the CeO2 incorporation decreased the number of acid sites, limiting cracking reactions and causing a significant drop in hydrogen production.