Ni/CaO-Al2O3 bifunctional catalysts for sorption-enhanced steam methane reforming



Ni/CaO-Al2O3 bifunctional catalysts with different CaO/Al2O3 mass ratios were prepared by a sol–gel method and applied to the sorption-enhanced steam methane reforming (SESMR) process. The catalysts consisted mainly of Ni, CaO and Ca5Al6O14. The catalyst structure depended strongly on the CaO/Al2O3 mass ratio, which in turn affected the CO2 capture capacity and the catalytic performance. The catalyst with a CaO/Al2O3 mass ratio of 6 or 8 possessed the highest surface area, the smallest Ni particle size, and the most uniform distribution of Ni, CaO, and Ca5Al6O14. During 50 consecutive SESMR cycles at a steam/methane molar ratio of 2, the thermodynamic equilibrium was achieved using the catalyst with a CaO/Al2O3 mass ratio of 6, and H2 concentration profiles for all the 50 cycles almost overlapped, indicating excellent activity and stability of the catalyst. Moreover, a high CO2 capture capacity of 0.44 inline image was maintained after 50 carbonation–calcination cycles, being almost equal to its initial capacity (0.45 inline image). © 2014 American Institute of Chemical Engineers AIChE J, 60: 3547–3556, 2014