Unveiling the Mechanism of Plasma-Catalytic Low-Temperature Water-Gas Shift Reaction over Cu/γ-Al₂O₃ Catalysts

The water-gas shift (WGS) reaction is a crucial process for hydrogen production. Unfortunately, achieving high reaction rates and yields for the WGS reaction at low temperatures remains a challenge due to kinetic limitations. Here, nonthermal plasma coupled to Cu/γ-Al₂O₃ catalysts was employed to enable the WGS reaction at considerably lower temperatures (up to 140 °C). For comparison, thermal-catalytic WGS reactions using the same catalysts were conducted at 140-300 °C. The best performance (72.1% CO conversion and 67.4% H₂ yield) was achieved using an 8 wt % Cu/γ-Al₂O₃ catalyst in plasma catalysis at ∼140 °C, with 8.74 MJ mol^-1 energy consumption and 8.5% H₂ fuel production efficiency. Notably, conventional thermal catalysis proved to be ineffective at such low temperatures. Density functional theory calculations, coupled with in situ diffuse reflectance infrared Fourier transform spectroscopy, revealed that the plasma-generated OH radicals significantly enhanced the WGS reaction by influencing both the redox and carboxyl reaction pathways.