Effect of V2O5 promoter on characteristics and performance of NiO/CeO2 catalyst in methane bi-reforming

Phan Hong Phuong, Luu Cam Loc, Nguyen Tri, Nguyen Thi Thuy Van, Nguyen Phung Anh, Nguyen Phuc Hoang Duy and Hoang Tien Cuong

Abstract

In this work, a series of 10 wt% NiO/CeO₂ catalysts (Ni/Ce) promoted by V₂O₅ with content varying in the range of 0–0.5 wt% was prepared by the co-impregnation method. The characteristics of the catalysts were investigated by several techniques including N₂ physisorption (BET), X-ray diffraction (XRD), Raman spectroscopy, transmission electron microscopy (TEM), EDS mapping, carbon dioxide temperature-programmed desorption (CO₂-TPD), and hydrogen temperature-programmed reduction (H₂-TPR). The activity of the catalyst was studied in the micro-flow system in a temperature range of 550 °C–800 °C, the feedstock composition CH₄/CO₂/H₂O of 3.0/1.2/2.4 and the weight hourly space velocity (WHSV) of 30,000 ml.h⁻¹.g⁻¹. Adding V₂O₅ additive, on the one hand increases the reducibility and basicity of Ni/Ce catalyst, on the other hand reduces oxygen vacancies and increases the crystal size of CeO₂, leading to various effects on catalyst activity depending on its content. Ni/Ce catalyst promoted with 0.3 wt% of V₂O₅ was the best among tested ones, on which at reaction temperature of 700 °C, the conversion of CH₄ and CO₂ reached 97% and 77% respectively, and the molar ratio of H₂/CO was 2.1. Meanwhile, on non-promoted Ni/Ce catalyst, the corresponding quantities were 83%, 62% and 1.9, respectively. It is important to note that performance of both was stable for more than 30 h thanks to the better resistance to coke deposition and structural stability.