Dry reforming of methane is a promising process to convert two greenhouse gases into syngas. Calcinated nickel silicate nanotubes (C-NSNT) as well as CeO_2-x interface-confined and nickel silicate nanotubes (NSNT)-derived Ni catalysts, which are marked as λCeO_2-x-NSNT (λ = 0.5, 1, 1.5 and 2.25), is prepared and evaluated in dry reforming of methane. Compared with C-NSNT, the λCeO_2-x-NSNT samples exhibit improved catalytic performance in dry reforming of methane, which is closely related to Ni-CeSiO_2-x interface along with extrinsic defects from the interfacial reaction between CeO₂ and NSNT during the reduction process. Extrinsic defects can generate oxygen vacancies that can be accompanied by Ce³⁺ species. The enhancement of catalytic activity is ascribed to confined effects of extrinsic defects at contact interface of Ni-CeSiO_2-x and electronic effects of CeO_2-x. Furthermore, Ni-CeSiO_2-x interface with rich extrinsic defects can promote the adsorption and activation of CO₂ as electron donor on reduced λCeO_2-x-NSNT catalysts, which is fast dissociated into CO* and O*. Meanwhile, oxygen vacancies can transfer adsorbed O* species to Ni active sites to promote the carbon gasification reaction, which is responsible for the enhancement of catalytic stability in methane dry reforming for λCeO_2-x-NSNT catalysts. 1.5CeO_2-x-NSNT sample with more extrinsic defects has particular higher catalytic stability due to the improvement of anti-coking.

Dan Guo

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