Bimetallic catalysts for CO2 capture and hydrogenation at simulated flue gas conditions

A study of a dual function material (DFM) for CO2 capture from O-2-containing flue gas with catalytic conversion to fuel is presented. The DFM is composed of an alkaline adsorbent in concert with a methanation catalyst supported on gamma-Al2O3. The process operates at 320 degrees C for both CO2 capture and fuel generation upon the addition of renewable H-2. Ni alone will not methanate adsorbed CO2 after exposure to O-2 in the flue gas during CO2 capture since it oxidizes and cannot be reduced to Ni metal under DFM conditions (320 degrees C). We report that small amounts of precious metal (<= 1% Pt, Pd or Ru) enhance the reduction and activation of Ni-containing DFM towards methanation even after O-2 exposure in a flue gas. While ruthenium is most effective, Pt and Pd all enhance reduction of oxidized Ni. In this study we attempt to replace some of the Ru in the DFM with less expensive Ni and demonstrate the advantages and disadvantages of this replacement. The main advantage of the presence of Ni is an increase in CO2 adsorption and increase in methane produced, however, at the expense of a lower methanation rate. Extended cyclic aging studies corroborate the stable performance of 1% Ru, 10% Ni, 6.1% Na2O/Al2O3.