Preparing a Zr-Doped CeO2 Nanorod to Improve the Catalytic Performance of the Ni-Based Catalyst for Dry Reforming of Methane by Enhancing Oxygen Supply

Abstract

Dry reforming of methane (DRM) is a feasible route to realize the resource utilization of greenhouse gases CO2 and CH4. The Ni-based catalyst is recognized as a potential catalyst for the industrialization of DRM. However, catalyst deactivation caused by carbon deposition is a challenge. Providing enough active oxygen species to accelerate the reaction between CHx (x = 0–3) and oxygen species is the key to inhibit coking. Ni-based catalysts loaded on a Zr-doped Ce1–xZrxO2 nanorod were prepared by a one-step hydrothermal method. Benefiting from lattice distortion caused by Zr doping, the Ni/Ce0.95Zr0.05O2 catalyst showed the best catalytic activity and stability. Compared with the Ni/CeO2 catalyst, the activation energy of CH4 and CO2 decreased by 20 and 22%, respectively. The 100 h stability test showed that the Ni/CeO2 catalyst was 10% deactivated, and the carbon deposition rate was 0.82 mgc·gcat·–1·h–1, while the Ni/Ce0.95Zr0.05O2 catalyst showed excellent stability. The extensive characterization of the catalysts indicated that the enhancement in DRM activity upon Zr doping could be attributed to the increase of oxygen vacancies and the improvement in lattice oxygen mobility. However, excessive Zr doping formed ZrO2 covering oxygen vacancies, resulting in decreased catalytic activity and stability. The results showed that lattice oxygen over the Ni/Ce0.95Zr0.05O2 catalyst not only participated in the oxidation of carbon intermediates but also contributed to the deep dissociation of CH4 over Ni through an oxygen-mediated dissociation pathway. Similarly, the redox cycle on the oxygen vacancies was also important for enhancing the CO2 adsorption activation to relieve the coking of the catalyst.