Sorption enhanced steam methane reforming based on nickel and calcium looping: a review

This review is focused on Sorption Enhanced Steam Methane Reforming (SESMR), an emerging process intensification of traditional Steam Methane Reforming (SMR), to produce H-2 by a more environmental friendly exploitation of natural gas, thanks to in-situ CO2 capture. Ni and CaO are respectively the most investigated materials for SMR catalysis and CO2 capture, used either on separated particles or in Combined Sorbent Catalyst Materials (CSCM); the latter is potentially more advantageous from the process point of view. Preferential conditions for SESMR based on Ni and CaO are about 650 degrees C and 1 atm, allowing to obtain H-2 with high purity (more than 95 vol% vs. 76 vol% in industrial SMR, both on dry dilution-free basis). For a continuous process, multicycle CaO regeneration is needed, by means of high temperature calcination (800-950 degrees C). The exploitation of Solid Oxides Fuel Cells (SOFC) flue hot gases, as well as oxy-fuel combustion, are suggested as regeneration strategies in studies concerning SESMR industrial scale-up, in combinations of packed beds or fluidised bed reactors with solid recirculation. Future studies should investigate materials stability in relevant industrial conditions, e.g. more severe regenerations under highly concentrated CO2 at high temperatures, or in presence of steam.