Perovskite-Based Phase Transition Sorbents for Sorption-Enhanced Oxidative Steam Reforming of Glycerol
Leo Brody, Runxia Cai, Alajia Thornton, Junchen Liu, Hao Yu, Fanxing Li
Abstract
Sorption-enhanced steam reforming represents an efficient strategy to produce concentrated hydrogen from superfluous carbonaceous feedstocks. However, commonly used CaO-based sorbents are prone to sintering, leading to a rapid loss in CO 2 sorption capacity and activity under repeated reaction cycles. Herein, we report perovskite-based phase transition sorbents (PTSs) capable of avoiding sintering and retaining both catalytic activity and sorption capacity. Specifically, A- and B-site doped SrFeO 3−δ, that is, Sr 1– x Ca x Fe 1– y Ni y O 3−δ (SCFN), were evaluated as PTSs for the sorption-enhanced steam reforming of glycerol. Packed bed reactor experiments were performed in conjunction with redox, bulk, surface, and morphology characterizations to evaluate SCFN’s performance and the underlying phase transition scheme. These characterizations revealed that reduced oxides from the A-site of the PTS (SrO, CaO) are carbonated during the reforming step before reversibly undergoing decarbonation at a higher temperature under an oxidizing environment. This study demonstrates that SCFN is a trifunctional material capable of (i) catalyzing the reforming of glycerol, (ii) absorbing CO 2 in situ, and (iii) reversibly releasing oxygen from lattice sites to enhance glycerol conversion. While all of the screened compositions achieved >87 vol % pre-breakthrough H 2 purities, SCFN-4691 (Sr 0.4 Ca 0.6 Fe 0.9 Ni 0.1 O 3−δ ) and SCFN-5591 (Sr 0.5 Ca 0.5 Fe 0.9 Ni 0.1 O 3−δ ) showed particularly high (95.6–97.3%) H 2 purities with stable CO 2 sorption capacities.