H2 production from bio-ethanol sorption enhanced steam reforming: screening of MgO-stabilized CaO-based sorbents through their properties and interaction with the catalyst

• Improved CO 2 capacity with cycles in sol–gel sorbent (0.38 g CO2 g -1 solid at 5th cycle) • Sol-gel sorbent required additional pelletization step. • Bulk density is an underrated variable that highly influences SESR operation. • Migration of calcium from CaO-based sorbent to Ni-Al 2 O 3 catalyst. • Catalyst deactivation by contact with sorbent in SESR conditions. H 2 production from bio-ethanol Sorption Enhanced Steam Reforming (SESR) offers great potential for obtaining high H 2 yields and H 2 purities with negative CO 2 emissions, but efficient sorbents that are compatible with reforming catalysts are required. In this study, several CaO-based sorbents stabilized with MgO were screened. The one prepared by sol–gel method achieved highest CO 2 uptake capacity (0.15 g CO2 cm -3 solid ) after five carbonation-calcination cycles. In cyclic bio-ethanol SESR, sorbents promoted the Ni-Al 2 O 3 catalyst deactivation by formation of calcium aluminates, which resulted in variable amounts of non-converted CH 4 in the pre-breakthrough stage subsequent to the initial cycles. Dolomite was the sorbent that less interacted with the catalyst, leading to H 2 production near 0.261 g H2 g -1 EtOH and H 2 purity approaching 100 mol % after five reactions.