Highly Dispersed Ni with Partial Coverage of CeO x Derived from NiCeO 2 Solid Solution for the Selective Reverse Water Gas Shift Reaction

The reverse water gas shift (RWGS) reaction is a key process for CO 2 utilization, and Ni-based catalysts are promising due to their high activity but often suffer from poor CO selectivity. Herein, NiCeO 2 solid solution catalysts prepared via a coprecipitation method with varying Ni loadings and calcination and reduction temperatures were explored for the RWGS reaction at atmospheric pressure with varying reaction temperature, H 2 /CO ratio, and gas hourly space velocity (GHSV). Introducing a small amount of Ni (0.5 wt·%) to CeO 2 enhanced the intrinsic activity dramatically by 95-fold, i.e., from 10.1 mmol CO ·g cat –1 ·h –1 for CeO 2 –500C-600R to 960.8 mmol CO ·g cat –1 ·h –1 for 0.5Ni–CeO 2 –500C-600R (calcined and reduced at 500 and 600 °C, respectively) at 600 °C and a H 2 /CO 2 of 2, and lowered the E a remarkably from 118.1 to 47.0 kJ·mol –1 . The optimal sample of 0.5Ni–CeO 2 –500C-600R achieved near-equilibrium CO 2 conversion with nearly 100% CO selectivity at 500–600 °C, a H 2 /CO of 2, and a GHSV of