Overcoming chemical equilibrium limitations using a thermodynamically reversible chemical reactor

Abstract

All real processes be they chemical, mechanical or electrical, are thermodynamically irreversible and therefore suffer from thermodynamic losses. Here, we report the design and operation of a chemical reactor capable of approaching thermodynamicallyreversible operation. The reactor was employed for hydrogen production via the watergas shift reaction, an important route to green hydrogen. The reactor avoids mixing reactant gases by transferring oxygen from the (oxidising) water stream to the (reducing) carbon monoxide stream via a solid-state oxygen reservoir consisting of a perovskite phase (La 0.6 Sr 0.4 FeO 3-). This reservoir is able to remain close to equilibrium with the reacting gas streams because of its variable degree of non-stoichiometry and thus develops a chemical memory which we employ to approach reversibility. We demonstrate this memory using operando, spatially-resolved, real-time, high-resolution x-ray powder diffraction on a working reactor. The design leads to a reactor unconstrained by overall chemical equilibrium limitations, which can produce essentially pure hydrogen and carbon dioxide as separate product streams.

Low temperature methane conversion with perovskite-supported exo/endo-particles

“…This set up is described in detail elsewhere. 6 The reactor of the system is a quartz tube with internal diameter of 4 mm and 2 mm wall thickness. The local temperature was recorded with a K-type thermocouple placed in contact with the quartz reactor tube and was increased from RT to the specic experiment's temperature at a rate of 5 C min À1 .…”

“…This results in reduced need for methane combustion, potentially higher selectivity and removes the need for product separation. [6][7][8][9] CH 4 + ABO 3 [MO] / CO + 2H 2 + ABO 3Àd [M] (1)…”

Combining Exsolution and Infiltration for Redox, Low Temperature CH4 Conversion to Syngas

“…Chemical looping (CL), originally implemented in the steam-iron process, was initially employed for hydrogen production via the water gas shift reaction [1]. CL has recently received a lot of attention due to benefits related to inherent product separation that result in more efficient and safer processes [2][3][4]. However, material requirements for CL processes have proven to be quite complex especially when applied for hydrocarbon conversion, e.g., methane.…”

Novel Perovskite Materials for Thermal Water Splitting at Moderate Temperature

“…In this context, perovskite oxides may stand as promising candidates for hydrogen production by thermochemical water splitting . The non‐stoichiometric perovskite acts as a solid‐state oxygen carrier, which facilitates water reduction into hydrogen …”