Hydrogen production from ethanol steam reforming over nickel based catalyst derived from Ni/Mg/Al hydrotalcite-like compounds

摘要

Nickel based catalysts derived from thermal decomposition of Ni/Mg/Al hydrotalcite-like precursors have been studied in ethanol steam reforming (ESR) for hydrogen production. X-ray diffraction (XRD), transmission electron microscopy (TEM), temperature-programmed reduction (TPR) and thermogravimetric analysis (TGA) were used to investigate the physic-chemical properties of the catalysts prepared. The catalysts being mainly composed of Ni-Mg-O solid solution phase exhibited high activity and stability for ethanol steam reforming. Ethanol could be completely converted even at 673 K, and hydrogen concentration tended to increase with increasing reaction temperature, gas hourly space velocity (GHSV) and Ni/Mg ratio. XRD and TEM investigations demonstrate that low Ni/Mg ratio led to insufficient Ni~0 phase available, which may result in decreasing activity and stability due to coke formation observed on the NiMg10 (Ni/Mg = 1/10) catalyst. High reduction pretreatment temperature (>973 K) could promote the reduction of Ni~0 metal, and effectively improve the catalytic activity and stability. The optimum reduction temperature might be 1073 K, at which proper amount of Ni~0 species and good resistance to coke formation could be obtained.