Catalytic and sorbent materials based on mayenite for sorption enhanced steam methane reforming with different packed-bed configurations

An experimental study was performed on sorption enhanced steam methane reforming (SESMR) by Ni-mayenite reforming catalyst and CaO-mayenite CO2-sorbents with several CaO contents. Materials were synthesized, characterized (by XRD, BET and BJH methods, TPR) and tested in a micro-reactor, comparing two configurations: two separated, consequential packed-beds and the more usual raw mixing. Ni-mayenite always allowed a high, stable CH4 conversion (>93%). A generalized direct effect from CO2 capture emerged on water gas shift reaction extent, while enhancement of methane conversion took place only in raw mixing. In practical applications, investigated materials are bound to face alternatively reforming and sorbent regeneration conditions: an automated bench-scale system was used to perform 205 SESMR/regeneration cycles, with separate beds of Ni-mayenite and CaO-mayenite (30 wt% free-CaO), proving good activity and stability throughout cycles (stable CH4 conversion > 95%, pre-breakthrough CO2 concentration < 3 vol% dry, dilution-free).