Comparative study on the promotion effect of Mn and Zr on the stability of Ni/SiO2 catalyst for CO2 reforming of methane

Abstract

The stability of Mn-promoted Ni/SiO2 catalyst for methane CO2 reforming was investigated comparatively to that of Zr-promoted Ni/SiO2. The catalysts were prepared by the same impregnation method with the same controlled promoter contents and characterized by TPR, XRD, TG, SEM, XPS and Raman techniques. The addition of Mn to Ni/SiO2 catalyst promoted the dispersion of Ni species, leading to smaller particle size of NiO on the fresh Ni–Mn/SiO2 catalyst and the formation of NiMn2O4, which enhanced the interaction of the modified support with Ni species. Thus, the Ni–Mn/SiO2 catalyst showed higher activity and better ability of restraining carbon deposition than Ni/SiO2 catalyst. Besides, it exhibited stable activity at reaction temperatures over the range from 600°C to 800°C. However, the introduction of Zr increased the reducibility of Ni–Zr/SiO2, and the catalyst deactivated much more dramatically when the reaction temperature decreased due to its poor ability of restraining carbon deposition, and its activity decreased monotonically with time on stream at 800°C.