Sorption-enhanced steam reforming of toluene using multifunctional perovskite phase transition sorbents in a chemical looping scheme

Sorption-enhanced steam reforming (SESR) of toluene (SESRT) using catalytic CO2 sorbents is a promising route to convert the aromatic tar byproducts formed in lignocellulosic biomass gasification into hydrogen (H-2) or H-2-rich syngas. Commonly used sorbents such as CaO are effective in capturing CO2 initially but are prone to lose their sorption capacity over repeated cycles due to sintering at high temperatures. Herein, we present a demonstration of SESRT using A- and B-site doped Sr(1-x )A' (x) Fe1-y B' (y) O3-delta (A' = Ba, Ca; B' = Co) perovskites in a chemical looping scheme. We found that surface impregnation of 5-10 mol% Ni on the perovskite was effective in improving toluene conversion. However, upon cycling, the impregnated Ni tends to migrate into the bulk and lose activity. This prompted the adoption of a dual bed configuration using a pre-bed of NiO/gamma-Al2O3 catalyst upstream of the sorbent. A comparison is made between isothermal operation and a more traditional temperature-swing mode, where for the latter, an average sorption capacity of similar to 38% was witnessed over five SESR cycles with H-2-rich product syngas evidenced by a ratio of H-2: CO (x) > 4.0. XRD analysis of fresh and cycled samples of Sr0.25Ba0.75Fe0.375Co0.625O3-delta reveal that this material is an effective phase transition sorbent-capable of cyclically capturing and releasing CO2 without irreversible phase changes occurring.

Automated summary

Sorption-enhanced steam reforming (SESR) of toluene using A- and B-site doped Sr(1-x)A'(x)Fe1-yB'(y)O3-delta perovskites in a chemical looping scheme shows promise in converting aromatic tar byproducts into hydrogen-rich syngas. Impregnating Ni on the perovskite surface improves toluene conversion, and a dual bed configuration enhances cyclic CO2 capture and release for H2-rich product syngas.