N2 RF-plasma-assisted preparation of small size Ni–Ce catalysts for dry reforming of methane with high activity and great coke-resistant performance

Abstract

High activity and stability are the goals sought for by industrial applications of dry reforming of methane (DRM). However, the particle size is not easy to control and carbon accumulations are key issues to be solved. Herein, a new Ce-doping Ni-based catalyst (Ni–Ce–P2h) with excellent coke resistance and eximious activity was prepared by the N2 Radio Frequency Plasma assisted impregnation method. The prepared materials were characterized by means of XRD, SEM, TEM, BET, H2-TPR, XPS and TG. The results showed that the plasma treatment time was important, and catalysts with 2 h of plasma treatment had the best catalytic performance. The initial activities of CH4 and CO2 for Ni–Ce–P2h catalyst both exceed 76% at 700 °C. Compared to the conventional catalyst Ni–C and Ni–Ce–C with high temperature calcination treatment, the initial conversion of CH4 and CO2 for Ni–Ce–P2h was improved by over 15% and 10%, respectively. Moreover, excellent stability of Ni–Ce–P2h was observed. The activity drop was no more than 3% after 10h long time reaction. And the amount of carbon accumulation was only 0.5%. The smaller grain size of active components Ni, the stronger metal-support interactions and more abundant oxygen species might be the main reasons for the better DRM performance on the Ni–Ce catalysts prepared by plasma-assisted method. The Ni particle size of the Ni–Ce–P2h catalyst was only 5.4 nm, which is much smaller than that of the Ni–C (24 nm) and Ni–Ce–C (20 nm). This study provides a new idea to explore the synergistic effect of Ce doping and the plasma treatment on Ni based catalyst with good DRM performance.