Synthesis, characterization, and application of bio-templated Ni–Ce/Al2O3 catalyst for clean H2 production in the steam reforming of methane process

Abstract

A mesoporous γ-alumina was successfully synthesized through an environmentally-friendly method using Fig leaves as a bio-template for the first time in this research. After confirming the formation of porous Al2O3 structure with different characterization techniques, it was used as a supporting material of Ni–Ce particles to effectively enhance the conversion of steam reforming of methane (SRM) process. For this purpose, we optimized Ni content, Ce content, and SRM temperature using bulk and porous structure of Ni–Ce/Al2O3 catalysts. The results of field emission scanning electron microscopy (FESEM), temperature-programmed desorption (H2-TPD), and N2 adsorption/desorption showed the formation of more dispersed Ni particles with smaller sizes on the mesoporous alumina (MAl), especially when they were promoted with CeO2. Besides the efficient influence of CeO2 on Ni particle dispersion, it was enhanced the Ni–Al interaction, increased the activity of the catalysts, and decreased the coke deposition on the catalysts during the SRM process. As a result, 20Ni-3.0Ce/MAl catalyst depicted the highest H2 yield of 96.02% and CH4 conversion of 90.20%, and the lowest produced CO2 to consumed CH4 of 0.52% at 700 °C SRM reaction. This is while the bulky catalyst with equal Ni and Ce contents had 86.09, 92.30, and 0.56 CH4 conversion, H2 yield, and CO2/CH4 molar ratio, respectively at this temperature. Besides, 20Ni-3.0Ce/MAl depicted the highest stability during 12 h continuous SRM reaction at 700 °C with the lowest reduction amounts of 3.97% and 5.12% for CH4 conversion and H2 yield, respectively.