Characterization and activity in dry reforming of methane on NiMg/Al and Ni/MgO catalysts

Abstract

Dry reforming of methane has been investigated on two series of catalysts either prepared by co-precipitation: n(Ni x Mg y )/Al, Ni x Mg y and Ni x Al y or prepared by impregnation: Ni/MgO (mol% Ni = 5, 10). The catalysts, calcined at 600–900 °C, were characterized by different techniques: BET, H 2-TPR, TPO, XRD, IR, and TEM-EDX analysis. The surface BET (30–182 m 2 g −1) decreased with increasing the temperature of calcination, after reduction and in the presence of Mg element. The XRD analysis showed, for n(Ni x Mg y )/Al catalysts, the presence of NiAl 2O 4 and NiO–MgO solid solutions. The catalyst reducibility decreased with increasing the temperature of pretreatment. The n(Ni x Mg y )/Al catalysts were active for dry reforming of methane with a good resistance to coke formation. The bimetallic catalyst Ni 0.05Mg 0.95 (calcined at 750 °C and tested at 800 °C) presents a poor activity. In contrast, the 5% Ni/MgO catalyst, having the same composition but prepared by impregnation, presents a high activity for the same calcination and reaction conditions. For all the catalysts the activity decreased with increasing the temperature of calcination and a previous H 2-reduction of the catalyst improves the performances. The TPO profiles and TEM-EDX analysis showed mainly four types of coke: CH x species, surface carbon, nickel carbide and carbon nanotubes.