Defect-induced formation of nickel silicates on two-dimensional MWW-type catalysts promoting catalytic activity for dry reforming of methane

Abstract

The surface properties of a catalyst support not only influence the chemical states of the impregnated metals, but also the catalytic performance. Here, we systematically investigated the role of support morphology and defect concentration on the catalytic activity for dry reforming of methane (DRM) by comparing three-dimensional (3D) and two-dimensional (2D) aluminosilicate, borosilicate, and deboronated MCM tWenty-tWo (MWW)-type catalysts. Changes in the surface properties by delamination and/or deboronation as well as their influence on the formation of nickel silicates were experimentally demonstrated. Density functional theory (DFT) calculations were also performed to estimate the stabilization of metallic Ni clusters by the introduction of silanol defect sites on the MWW-type support. The delaminated–deboronated 2D MWW-type catalyst with the highest concentration of nickel silicates, and accordingly, the highest amount of silanol defect sites exhibited remarkable CH4 and CO2 conversions as well as stability for DRM. Unlike conventional Ni/γ-Al2O3, the Ni species in nickel silicate 2D MWW-type catalysts were readily reduced to metallic Ni even without pre-reduction by H2, which is advantageous for practical applications.