Phase Composition of Ni/Mg_1−xNi_xO as a Catalyst Prepared for Selective Methanation of CO in H₂‐Rich Gas

Abstract

Supported Ni catalysts Ni/Mg 1− Ni O were prepared by reducing samples NiO-MgO in H 2 /N 2 mixture gas at 500 ∘ C∼800 ∘ C for selective methanation of CO in H 2 -rich gas (CO-SMET). The samples NiO-MgO were obtained by heating water slurry of MgO and Ni(NO 3 ) 2 in a rotary evaporator at 80 ∘ C and a final calcination in air at 400 ∘ C∼800 ∘ C. X-ray diffraction (XRD) and temperature programmed reduction (TPR) measurements demonstrate that the samples NiO-MgO were composed of solid solution Mg 1− Ni O as the main phase and a minor amount of NiO at calcination temperature of 400 ∘ C, and amount of the NiO was decreased as calcination temperature increased. Phase composition of the catalysts Ni/Mg 1− Ni O was estimated by the Rietveld method. Effects of reduction temperature, feed Ni/Mg ratio, and calcination temperature on phase composition and catalytic activity of the catalysts were investigated. It is clear that CO conversion was generally enhanced by an increased amount of metallic Ni of the catalysts.

Cation reducibility of LaNi0.5Ti0.5O3, LaNi0.5Ti0.45Co0.05O3, and LaNi0.45Co0.05Ti0.5O3 perovskites from X-ray powder diffraction data using the Rietveld method

“…Rietveld refinement of X-ray diffraction pattern of the sample after the reduction process can be used to determine the reduction degree of any crystalline material. By using this methodology, the reduction degree of the carbon-supported cobalt (Ghogia et al , 2020), Ni/Mg 1− x Ni x O (Zhang et al , 2015), Fe/TiO 2 (Rayner et al , 2014) catalysts, or the LaNi 0.5 Ti 0.5 O 3 , LaNi 0.5 Ti 0.45 Co 0.05 O 3 , and LaNi 0.45 Co 0.05 Ti 0.5 O 3 perovskites (Tuza and Souza, 2016, 2017) was determined. Regarding these last La containing perovskites, the La 2 NiO 4 phase was not taken into account and the details of Rietveld refinement was not reported.…”