Sorption enhanced steam methane reforming byNi/CaO/mayenite combined systems: Overview of experimental results fromEuropean research projectASCENT

Work Package 4 (WP4) of the European research project ASCENT developed combined sorbent-catalyst materials (CSCM) for sorption enhanced steam methane reforming (SESMR), based on nickel (Ni) and calcium oxide (CaO). This work summarizes the whole experimental study carried out in ASCENT WP4 on Ni/CaO/mayenite systems obtained from wet mixing and wet impregnation synthesis methods. Effects from Ni precursor (Ni (CH3COO)(2)center dot 4H(2)O or Ni(NO3)(2)center dot 6H(2)O), Ni load (from 3 wt%-10 wt%), and free CaO load (from 0 wt%-54 wt%) were investigated for 26 materials by means of characterizations and reforming reactivity tests in a packed-bed microreactor (650 degrees C, 1 atm). Thanks to comparative analyses of the results, evidence emerged about the detrimental influence of low Ni/CaO ratio on the reforming catalytic activity of solid inventories, made of CSCM or even of the raw mixing of CaO-mayenite and Ni-mayenite particles. Catalytic materials were active towards reforming only when derived from Ni(NO3)(2)center dot 6H(2)O. Based on this, the best CSCM (with the lowest free CaO content and the highest Ni load from nickel nitrate) was chosen to further study its industrial applicability by multicycle SESMR/sorbent-regeneration tests in a bench-scale packed-bed rig and attrition tests according to ASTM D5757-11. The CSCM was stable and active for 200 cycles with regenerations in N(2)at 850 degrees C, while a progressive loss of its activity occurred with regenerations in CO(2)at 925 degrees C as the cycle number increased due to Ni sintering. Its performance in the attrition tests was comparable to that of calcined dolomite.