Mesoporous nanocrystalline ceria-zirconia solid solutions supported nickel based catalysts for CO_2 reforming of CH_4

摘要

A series of mesoporous nanocrystalline ceria-zirconia solid solutions with different Ce/Zr ratios were facilely synthesized via improved evaporation induced self-assembly strategy. The obtained materials with advantageous structural properties and excellent thermal stabilities were characterized by various techniques and investigated as the supports of the Ni based catalysts for CO_2 reforming of CH_4. The effects of Ce/Zr ratio and mesopore structure on promoting catalytic performances had been investigated. It was found that the catalyst supported on carrier with 50/50 Ce/Zr ratio behaved the highest catalytic activity. The reason for this might be that the mesoporous ceria-zirconia solid solution carrier contributed to the activation of CO_2 by its own redox property. Compared with the catalyst without obvious mesostructure, the current mesoporous catalyst performed higher catalytic activity and better catalytic stability, demonstrating the advantages of the mesostructure. On the one hand, the predominant textural properties such as large surface area, big pore volume, and uniform channel helped to the high dispersion of the Ni particles among the mesoporous framework, finally leading to higher catalytic activity. On the other hand, the mesoporous matrix could stabilize the Ni nanoparticles under severe reduction and reaction conditions by the "confinement effect", committed to better catalytic stability. Besides, the properties of the coke over the mesoporous catalyst were also carefully studied. Generally, these mesoporous nanocrystalline ceria-zirconia solid solutions were a series of promising catalytic carriers for CO_2 reforming of CH_4.