Characterization of olivine-supported nickel silicate as potential catalysts for tar removal from biomass gasification

• Naturally-occurring olivine has potential as a catalyst support.
• Nickel silicate supported on olivine has potential for in situ tar removal.
• Thermal impregnation parameters can change the catalytic performance.
• Higher thermal impregnation temperatures increase resistance to coking.

In this work olivine-supported nickel silicate, which was prepared by thermal impregnation is considered as a potential tar removal catalyst for cleaning the gas stream during biomass gasification. Previous work on Ni-olivine catalysts has shown that these catalysts have good activity for the tar-reforming reaction as well as good stability and tolerance to coking. In this work, various characterization techniques such as X-ray diffraction, X-ray photoelectron spectroscopy, laser Raman spectroscopy, temperature programmed reduction, temperature programmed reaction, and subsequent temperature programmed oxidation are employed to reveal the properties of the catalyst surface and bulk as well as their relationship to catalytic activity. Higher thermal impregnation temperatures produce stronger interactions between the active component and support, leading to better coke tolerance. Relative amounts of reducible Ni, Fe species and surface Mg have an influence on catalytic behavior. Moreover, compared to olivine, the Ni2SiO4/olivine catalyst exhibits good catalytic activity for dry reforming, water gas shift, reverse water gas shift and methanation reactions, as well as the steam reforming reaction.

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