Catalytic decomposition of CH_4 over NiO-Al_2O_3-SiO_2 catalysts: Influence of catalyst preparation conditions on the production of H_2

摘要

This paper presents the synthesis and characterization of NiO-Al_2O_3-SiO_2 catalysts prepared by co-precipitation method and the catalytic activities estimated for the production of H_2 by CH_4 decomposition. The physico-chemical characteristics are evaluated by XRD analysis, TPR and O_2 pulse chemisorption, XPS, CHNS, SEM/EDAX, TEM and BET-surface areas of fresh and used forms of catalysts. XRD studies revealed the presence of hydrotalcite-like precursors in oven dried form and produced dispersed NiO species upon calcination in static air at 450 ℃. The catalyst compositions for NiO-Al_2O_3-SiO_2 system are optimized based on various parameters such as varying Ni loadings, change in Al/ Si ratios, precipitation at different pH and finally choice of precursors on CH_4 decomposition activities. Based on the results it is concluded that the composition of NiO-Al_2O_3-SiO_2 and preparation conditions played a key role in the decomposition of CH_4. The optimized compositions are established for the production of H_2 that can be utilized in fuel cell applications.