Effect of V <sub>2</sub> O <sub>5</sub> promoter on characteristics and performance of NiO/CeO <sub>2</sub> catalyst in methane bi-reforming
Phan Hong Phuong, Lưu Cẩm Lộc, Nguyen Tri, Nguyen Thi Thuy Van, Nguyen Phung Anh, Nguyen Phuc Hoang Duy, Hoang Tien Cuong
Abstract
Abstract In this work, a series of 10 wt% NiO/CeO 2 catalysts (Ni/Ce) promoted by V 2 O 5 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 N 2 physisorption (BET), X-ray diffraction (XRD), Raman spectroscopy, transmission electron microscopy (TEM), EDS mapping, carbon dioxide temperature-programmed desorption (CO 2 -TPD), and hydrogen temperature-programmed reduction (H 2 -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 CH 4 /CO 2 /H 2 O of 3.0/1.2/2.4 and the weight hourly space velocity (WHSV) of 30,000 ml.h −1 .g −1 . Adding V 2 O 5 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 CeO 2 , leading to various effects on catalyst activity depending on its content. Ni/Ce catalyst promoted with 0.3 wt% of V 2 O 5 was the best among tested ones, on which at reaction temperature of 700 °C, the conversion of CH 4 and CO 2 reached 97% and 77% respectively, and the molar ratio of H 2 /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.