Characterization and activity test of commercial Ni/Al_2O_3, Cu/ZnO/Al_2O_3 and prepared Ni-Gu/Al_2O_3 catalysts for hydrogen production from methane and methanol fuels

摘要

In this study, methane and methanol steam reforming reactions over commercial Ni/Al_2O_3, commercial Cu/ZnO/Al_2O_3 and prepared Ni-Cu/Al_2O_3 catalysts were investigated. Methane and methanol steam reforming reactions catalysts were characterized using various techniques. The results of characterization showed that Cu particles increase the active particle size of Ni (19.3 nm) in Ni-Cu/Al_2O_3 catalyst with respect to the commercial Ni/ A1_2O_3 (17.9). On the other hand, Ni improves Cu dispersion in the same catalyst (1.74%) in comparison with commercial Cu/ZnO/Al_2O_3 (0.21%). A comprehensive comparison between these two fuels is established in terms of reaction conditions, fuel conversion, H_2 selectivity, CO_2 and CO selectivity. The prepared catalyst showed low selectivity for CO in both fuels and it was more selective to H_2, with H_2 selectivities of 99% in methane and 89% in methanol reforming reactions. A significant objective is to develop catalysts which can operate at lower temperatures and resist deactivation. Methanol steam reforming is carried out at a much lower temperature than methane steam reforming in prepared and commercial catalyst (275-325 ℃). However, methane steam reforming can be carried out at a relatively low temperature on Ni-Cu catalyst (600-650 ℃) and at higher temperature in commercial methane reforming catalyst (700-800 ℃). Commercial Ni/Al_2O_3 catalyst resulted in high coke formation (28.3% loss in mass) compared to prepared Ni-Cu/Al_2O_3 (8.9%) and commercial Cu/ZnO/Al_2O_3 catalysts (3.5%).