Flame-driven aerosol synthesis of stable, high-performance, and CO₂ tolerant high-temperature water gas shift (HT-WGS) reaction catalysts using multiple promoters

The water gas shift reaction is a moderately exothermic reaction that converts carbon monoxide and steam (CO and H₂O) to carbon dioxide and hydrogen (CO₂ and H₂). In combination with CO₂ capture, it is an important component in the production of “blue” hydrogen. However, commercial ferrochrome catalysts have limited catalytic activity and suffer from CO₂ inhibition and deactivation under CO₂-rich conditions. CO₂ inhibition particularly limits their performance in catalytic membrane reactors in which H₂ removal is integrated with reaction for process intensification and to achieve higher CO conversion at lower temperature . To address this gap, we designed and prepared a novel high entropy metal oxide (HEMO), high performing, and ultrastable CO₂-tolerant (FeCrMnCoNi)O _x -FS nano-catalyst using a unique flame-based aerosol process. Compared with conventional ferrochrome catalysts, the flame-synthesized HEMO demonstrates significantly higher CO conversion (∼90% at 425 °C and a gas-hourly space velocity (GHSV) of 33,000 mL·g_cat⁻¹·h⁻¹), and promising stability over 100 h of testing under HT-WGS conditions. The catalyst from this gas-phase synthesis method also outperforms an analogous catalyst co-precipitated from solution (FeCrMnCoNi)O _x -CP or created by solid-state ball-milling of the component oxides (FeCrMnCoNi)O _x -BM. Kinetic studies on these HEMO catalysts were conducted to quantify and confirm reduced CO₂ and H₂O inhibition along with activation energies. These results highlight the potential of HEMO catalysts in general, and flame aerosol technology in particular for scalable production of efficient and sustainable catalysts for hydrogen production.