Hydrotalcite structure derived Ni-Cu-Al catalysts for the production of H_2 by CH_4 decomposition

摘要

The precursors of hydrotalcite-like structures of Ni-Cu-Al catalysts derived with different Cu/Al ratios have been synthesized by coprecipitation method. The CH_4 decomposition activities are evaluated at 600-700 ℃ and ambient pressures over calcined Ni-Cu-Al catalysts until the catalysts were deactivated completely. The physico-chemical characteristics of the fresh catalysts are obtained using BET surface area, X-ray diffraction (XRD), temperature programmed reduction (TPR), TGA, SEM/EDAX and X-ray photoelectron spectra (XPS) analyses and the deactivated catalysts are investigated by transmission electron microscopy (TEM), Raman and CHNS analyses. The Raman spectra revealed the presence of both ordered and disordered forms of carbon in the deactivated catalysts. Higher H_2 yields are obtained over Ni-Cu-Al (60:25:15 mol%) catalyst.