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

Abstract

Ni/CaO‐Al 2 O 3 bifunctional catalysts with different CaO/Al 2 O 3 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 Ca 5 Al 6 O 14 . The catalyst structure depended strongly on the CaO/Al 2 O 3 mass ratio, which in turn affected the CO 2 capture capacity and the catalytic performance. The catalyst with a CaO/Al 2 O 3 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 Ca 5 Al 6 O 14 . During 50 consecutive SESMR cycles at a steam/methane molar ratio of 2, the thermodynamic equilibrium was achieved using the catalyst with a CaO/Al 2 O 3 mass ratio of 6, and H 2 concentration profiles for all the 50 cycles almost overlapped, indicating excellent activity and stability of the catalyst. Moreover, a high CO 2 capture capacity of 0.44 was maintained after 50 carbonation–calcination cycles, being almost equal to its initial capacity (0.45 ). © 2014 American Institute of Chemical Engineers AIChE J , 60: 3547–3556, 2014