Enhancing methane formation in carbon dioxide hydrogenation on nickel clusters with zirconium additives: Exploring active sites, reaction pathways, and catalytic mechanisms

This study focuses on the catalytic reaction of carbon dioxide (CO₂) hydrogenation using 0.5 wt% nickel (Ni) deposited on silica oxide support (SiO₂). Initially, these Ni clusters exhibit limited catalytic activity and selectivity toward carbon monoxide (CO) formation. However, the introduction of zirconium ions (Zr⁴⁺) onto the Ni clusters leads to a remarkable improvement in the catalytic efficiency of CO₂ hydrogenation and methane (CH₄) production. The interaction between Ni and ZrO₂ generates interfacial sites that play a multifaceted role. These sites facilitate the binding of acidic CO₂ and promote the atomic hydrogen migration from ZrO₂ to Ni. Consequently, the creation of interfacial sites on the Ni catalysts directly enhances the rate of CO₂ hydrogenation while also increasing CH₄ selectivity. The primary intermediate in this process appears to be monodentate formate species, which can undergo direct decomposition to CO or conversion into formic acid intermediates. The formic acid intermediates subsequently undergo hydrogenation, ultimately leading to the production of CH₄.