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Metal-oxide promoted Ni/Al <inf>2</inf> O <inf>3</inf> as CO <inf>2</inf> methanation micro-size catalysts

Abstract:

The Power-to-Gas concept has the challenge to convert the excess of renewable electricity to synthetic natural gas, composed mainly by methane, through CO 2 methanation. The superior heat transfer capacity of micro-structured reactors offers a suitable alternative for an efficient control of the reaction temperature. In the present work, the strategy of adding large amount of metal oxide promoters (15 wt.%) to nickel supported on micro-size catalysts (d p = 400-500 μm) is presented. The addition of CeO 2 , La 2 O 3 , Sm 2 O 3 , Y 2 O 3 and ZrO 2 was clearly beneficial, as the corresponding metal-oxide promoted catalysts exhibited higher catalytic performance than Ni/Al 2 O 3 and the commercial reference Meth ® 134 (T = 200-300 °C, P = 5 bar·g). This increase of catalytic activity is attributed to the higher amount of CO 2 adsorbed on the catalyst. Among the selected promoters, La 2 O 3 showed the highest catalytic activity (X CO2 =+20% at 300 °C) due to the enhancement of nickel reducibility, nickel dispersion and the presence of moderate basic sites. In addition, Ni-La 2 O 3 /Al 2 O 3 was stable for one week, while the unpromoted catalyst exhibited a slight decline in its activity. Accordingly, the technical catalyst proposed in this study could be used directly in compact reactors for CO 2 methanation with much higher activity than the commercial reference.