The cognition of active sites in the Ni-based catalysts plays a vital role and remains a huge challenge in improving catalytic performance of low temperature CO2 dry reforming of methane(LTDRM).In this work,typical catalysts of SiO2 and γ-Al2O3 supported Ni and Ni-Ce were designed and prepared.Importantly,the difference in the chemical speciations of active sites on the Ni-based catalysts is revealed by advanced characterizations and further estimates respective catalytic performance for LTDRM.Results show that larger[Nin0]particles mixed with[Ni-O-Sin])species on the Ni/SiO2(R)make CH4 excessive decomposition,leading to poor activity and stability.Once the Ce species is doped,however,superior activity(59.0％CH4 and 59.8％CO2 conversions),stability and high H2/CO ratio(0.96)at 600℃can be achieved on the Ni-Ce/SiO2(R),in comparison with other catalysts and even reported studies.The improved performance can be ascribed to the formation of integral([Nin0]-[CeⅢ-□-CeⅢ])species on the Ni-Ce/SiO2(R)catalyst,containing highly dispersed[Nin0]particles and rich oxygen vacancies,which can synergistically establish a new stable balance between gasification of carbon species and CO2 dissocia-tion.With respect to Ni-Ce/γ-Al2O3(R),the Ni and Ce precursors are easily captured by extra-framework Aln-OH groups and further form stable isolated([Nin0]-[Ni-O-Aln])and[CeⅢ-O-Aln]species.In such a case,both of them preferentially accelerate CO2 adsorption and dissociation,causing more car-bon deposition due to the disproportionation of superfluous CO product.This deep distinguishment of chemical speciations of active sites can guide us to further develop new efficient Ni-based catalysts for LTDRM in the future.

Yimin Zhang;Ruiming Zeng;Yun Zu;Linhua Zhu;Yi Mei;Yongming Luo;Dedong He

Faculty of Chemical Engineering,Kunming University of Science and Technology,Kunming 650500,China;Faculty of Environmental Science and Engineering,Kunming University of Science and Technology,Kunming 650500,China;National Engineering Laboratory for Flue Gas Pollutants Control Technology and Equipment,Tsinghua University,Beijing 100084,China

中国化学工程学报（英文版）

[1]Yimin Zhang;Ruiming Zeng;Yun Zu;Linhua Zhu;Yi Mei;Yongming Luo;Dedong He-.Low-temperature dry reforming of methane tuned by chemical speciations of active sites on the SiO2 and y-Al2O3 supported Ni and Ni-Ce catalysts)[J].中国化学工程学报（英文版）,2022(08):76-90

speciations,LTDRM,Nin0,dissocia,Aln,superfluous,distinguishment

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