Silicotungstic acid-derived WO3 composited with ZrO2 supported on SBA-15 as a highly efficient mesoporous solid acid catalyst for the alkenylation of p-xylene with phenylacetylene

Highly dispersed silicotungstic acid-derived WO₃ composited with ZrO₂ supported on SBA-15 (WZ/SBA-15) as an ordered mesoporous solid acid catalyst was prepared via a facile incipient wetness impregnation (IWI) method that active ingredients, ZrO₂ and WO₃, were impregnated into the channels of SBA-15 simultaneously with a subsequent calcination process. The relationship between catalyst nature and performance was explored by high resolution transmission electron microscopy (HRTEM), high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), FT-IR, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), N₂ adsorption-desorption, NH₃ temperature-programmed desorption (NH₃-TPD), and FT-IR of pyridine adsorption (Py-IR) characterization techniques. The catalytic performance of W₁₂Z₁₅/SBA-15 is not only greater than that of single component solid acid catalysts, WO₃/SBA-15 and ZrO₂/SBA-15, but also W₁₂/Z₁₅/SBA-15 prepared by impregnating active ingredients, ZrO₂ and WO₃, into SBA-15 in sequence. The outstanding performance of W₁₂Z₁₅/SBA-15 is derived from the strong interaction between ZrO₂ and WO₃, which results in more acid sites, and relatively high specific surface area, large pore volume, and ordered mesoporous structure of SBA-15. The characterization and reaction results clearly demonstrate that the synergy of ZrO₂ and WO₃ has a clear boost for the alkenylation. The optimized W₁₂Z₁₅/SBA-15-500 achieves a 99.4% conversion of phenylacetylene and a 92.3% selectivity of main product α-arylstyrene for the alkenylation of p-xylene with phenylacetylene, with very low level of oligomers producing at the same time. Moreover, W₁₂Z₁₅/SBA-15-500 shows excellent catalytic stability and regeneration. Therefore, W₁₂Z₁₅/SBA-15-500 is a promising solid acid catalyst for the alkenylation.