Engineering Strongly Interacting Ni over CeO₂–Al₂O₃ Nanomixed Support Using Facile Steam Treatment for Enhanced CO₂ Hydrogenation

The activity and selectivity of catalytic reactions are profoundly influenced by metal–support interactions. The strong metal–support interaction (SMSI) plays a critical role in selectively driving the conversion of CO2 toward CO instead of CH4 in Ni-based catalytic systems. Moreover, the dispersion of active species governs the population of accessible reaction sites, thereby enhancing catalytic activity. In this work, highly efficient SMSI was successfully constructed via steam aging post-treatment over CeO2–Al2O3 nanocrystalline loaded Ni catalysts (NiCeAl). Remarkably, the NiCeAl–H2O catalyst achieves ∼50% CO2 conversion with 90% CO selectivity at 600 °C, representing a dramatic improvement over the untreated NiCeAl catalyst (23% CO2 conversion with ∼92% CO selectivity). Furthermore, the steam-treated catalyst demonstrates superior stability in prolonged CO2 hydrogenation tests, maintaining its performance with only a ∼4% conversion decrease over 10 h of continuous operation. In situ diffuse reflectance infrared Fourier transform spectroscopy analysis revealed that CO2 chemisorbs on the catalyst surface to form bidentate carbonates, which undergo sequential hydrogenation to form formate intermediates. These formate species subsequently decompose catalytically to produce CO, with the enhanced MSI in NiCeAl–H2O facilitating optimal CO desorption kinetics, thereby promoting superior reverse water–gas shift activity.