Synthetic natural gas by direct CO2 hydrogenation on activated takovites: effect of Ni/Al molar ratio

• Main Authors: Abelló, S, Berrueco, C, Gispert-Guirado, F, Montané, D
• Format: Journal Article
• Language: English
• Published: 01.01.2016
• ISSN: 2044-4753; 2044-4761
• DOI: 10.1039/c5cy01200g

Takovite-derived mixed oxides in Ni/Al molar ratios from 1 to 3 have been used as catalysts in hydrogenation of CO 2 to CH 4 . The catalysts were characterized by XRD, BET, TEM, TGA, and H 2 -TPR, and monitored by in situ DRIFTS under reaction conditions. The catalytic performance for the CO 2 methanation has been investigated in a fixed-bed reactor at the temperature range from 225 to 400 °C and pressures of 10.0 and 1.0 bar(g). Takovite decomposition leads to the formation of a NiO phase containing Al ions and a nickel-containing alumina phase (Ni-deficient spinel). The percentage of spinel increases upon decreasing the Ni/Al ratio, and consequently, a lower amount of metallic nickel after subsequent reduction is achieved. All catalysts were partially reduced upon time on stream, leading to the formation of small Ni 0 crystallites ( ca. 3 nm) dispersed on a NiAl 2 O 4 matrix. The most active and selective catalyst was the one with a Ni/Al ratio of 2, which was also very stable after a 500 h lifetime test at atmospheric pressure and 275 °C. Small Ni 0 crystallites dispersed over a NiAl 2 O 4 matrix, attained from takovite-like precursors, induced high catalytic performance in CO 2 methanation.