Hollow sphere Ni-based catalysts promoted with cerium for steam reforming of methane

Abstract

Investigation is made in this paper on the performance of hollow sphere Al2O3 supporting material in the steam reforming of methane (SRM). For this purpose, a series of Ni/hollowAl2O3 (Ni/HAl) catalysts promoted with CeO2 are synthesized and a detailed comparison is made between their structural properties, as well as catalytic activity and stability, with Ni/bulkAl2O3 (Ni/BAl). The influence of SRM temperature (600–700 °C), steam/methane (S/M) molar ratio (1.5–3.0), Ni loading (15-25 wt%), and Ce loading (1.5 and 3.0 wt%) are investigated for both Ni/Al2O3 structures. Different characterization techniques are performed on the synthesized supports, as well as catalysts, before and/or after SRM reaction. Better dispersed Ni active sites and thus higher catalytic activity and stability are achieved using 1.5Ce-promoted 20Ni/HAl catalyst which may be the result of higher surface area of HAl support compared with BAl. 20Ni-1.5Ce/HAl depicts the highest CH4 conversion of 92.06%, H2 yield of 97.03%, and H2/CO molar ratio of 6.40 at 700 °C with S/M molar ratio of 2.0. Besides, the less activity reduction of 6.07% and the less deposited coke of 4.01% is achieved during 12h reaction at 700 °C for 20Ni-1.5Ce/HAl. Therefore, this catalyst is not only a good choice for producing H2 energy carrier, but also is an appropriate catalyst for reducing the amount of CH4 greenhouse gas.