Highly active and stable Ni-based bimodal pore catalyst for dry reforming of methane

Abstract

Bimodal pore NiCeMgAl catalysts were synthesized via the refluxed co-precipitation method. Methane reforming using carbon dioxide over this bimodal pore NiCeMgAl catalyst for syngas production was systematically studied by optimizing the active component NiO-loading, calcination temperature, reduction temperature and gas hourly space velocity (GHSV). The Ni15CeMgAl sample with 15wt% NiO loading, was found to be active enough at 750°C with a high CH4 conversion of 96.5%. The proper reduction temperature for the NiCeMgAl catalyst is either 550–650°C or 850°C. Higher calcination temperature favors the formation of NiAl2O4 and MgAl2O4 spinel structures. The Ni active sites derived from the NiAl2O4 spinel structure had longer stability than those from the free NiO. Compared with non-bimodal pore NiCeMgAl catalyst, bimodal pore NiCeMgAl catalyst has a longer stability in the feed gas without dilution. The large pores in the bimodal pore Ni15CeMgAl catalyst were supposed to contribute to the quick molecule transfer during the dry reforming of methane (DRM) reaction when the GHSV was less than 96,000h−1. The evolution of the Ni15CeMgAl catalyst before and after the DRM reaction was investigated by BET, XRD, TEM, and TGA techniques. A schema of the DRM reaction on the bimodal pore Ni15CeMgAl catalyst was proposed, and the correlation between the structure evolution and catalytic performance change was also discussed.