Synergistic Catalysis at the Ni/ZrO<sub>2–<i>x</i></sub> Interface toward Low-Temperature CO<sub>2</sub> Methanation
Hui Wang, Zeyang Li, Guoqing Cui, Min Wei
Abstract
The CO 2 methanation reaction, which achieves the carbon cycle and gains value-added chemicals, has attracted much attention, but the design and exploitation of highly active catalysts remain a big challenge. Herein, zirconium dioxide-supported Ni catalysts toward low-temperature CO 2 methanation are obtained via structural topological transformation of NiZrAl-layered double hydroxide (LDH) precursors, which have the feature of an interfacial structure (Ni–O–Zr 3+ –Vö) between Ni nanoparticles and ZrO 2– x support (0 < x < 1). The optimized catalyst (Ni/ZrO 2– x -S2) exhibits exceptional CO 2 conversion (∼72%) at a temperature as low as 230 °C with a ∼100% selectivity to CH 4, without obvious catalyst deactivation within a 110 h reaction at a high gas hourly space velocity of 30,000 mL·g –1 ·h –1 . Markedly, the space–time yield of CH 4 reaches up to ∼0.17 m o l C H 4 ·g cat –1 ·h –1, which is superior to previously reported Ni catalysts evaluated under similar reaction conditions. Both in situ/operando investigations (diffuse reflectance infrared Fourier transform spectroscopy and X-ray absorption fine structure) and catalytic evaluations substantiate the interfacial synergistic catalysis at the Ni/ZrO 2– x interface: the Zr 3+ –Vö facilitates the activation adsorption of CO 2, while the H 2 molecule experiences dissociation at the metallic Ni sites. This work demonstrates that the metal–support interface effect plays a key role in improving the catalytic behavior toward CO 2 methanation, which can be extended to other high-performance heterogeneous catalysts toward structure-sensitive systems.