Geometric Matching Effect Induced High Dispersion of Na2WO4 Nanocluster on Cristobalite Support for Efficient Methyl Chloride-to-Vinyl Chloride Conversion

The oxidative coupling of methyl chloride (CH3Cl) to vinyl chloride (C2H3Cl) (MCTV) represents a promising yet challenging direct conversion route for C2H3Cl production. In this study, a novel catalyst, cristobalite silica, supported Na2WO4 nanoclusters, was fabricated by calcining an intermediate composite composed by β-zeolite and sodium tungstate (Na2WO4). The pore structure of this β-zeolite possesses a regular shape and suitable size distribution, providing an accurate geometric matching effect for Na2WO4 to homogeneously distribute in the entire β-zeolite matrix with high loading. Accordingly, the excellent dispersity of Na2WO4 nanocluster active sites is well maintained even after calcining at 750 °C, and the microporous β-zeolite matrix is completely converted to dense cristobalite phase silica after the calcination. The high-loading and well-dispersed Na2WO4 nanocluster leads to a superior performance in MCTV with a CH3Cl conversion of 81.5%, a C2H3Cl selectivity of 42.4%, and a C2H3Cl yield of 34.6%. Notably, the catalyst exhibits remarkable stability during the catalytic process.