Study On Preparation Of Supported Tungstated Zirconia Mesoporous Solid Acid Catalyst And Performance For Alkenylation

Alkenyl aromatics,known as important organic intermediates used in diverse fields,can be synthesized through the direct alkenylation of aromatics with alkynes over noble metal catalysts and acid catalysts.However,due to the high preparation cost of noble metal catalysts and the corrosion of the equipment resulting from the use of liquid acids,the further energy has to be put into developing novel catalysts for the alkenylation.Solid acid catalysts have attracted considerable attention due to the features of low cost,easy-separation and so on.Particularly,tungstated zirconia catalysts have been applied to diverse reactions owing to their enhanced regeneration ability and good thermal,but rare reports on alkenylation.Therefore,it is wise to load tungstated zirconia onto suitable porous carriers to obtain outstanding solid acid catalysts for alkenylation considering the mass transfer.In this work,incipient-wetness impregnation method was used to load active ingredients,zirconium dioxide and tungsten trioxide,onto SBA-15,and the obtained supported tungstated zirconia solid acid catalysts were applied to catalyze the alkenylation of p-xylene with phenylacetylene.Moreover,diverse characterization techniques including high resolution transmission electron microscopy（HRTEM）,high-angle annular dark-field scanning transmission electron microscopy（HAADF-STEM）,N₂ adsorption-desorption,X-ray diffraction（XRD）,FT-IR,NH₃ temperature-programmed desorption（NH₃-TPD）,FT-IR of pyridine adsorption（Py-IR）and X-ray photoelectron spectroscopy（XPS）were employed to obtain the relevant properties of the as-prepared solid acid catalysts and reveal the relationship between the catalysts’nature and catalytic performance.The main conclusions are summarized as follows:1.W₁₂Z₁₅/SBA-15 solid acid catalyst was obtained by the method that active ingredients,zirconium dioxide and tungsten trioxide,were impregnated onto SBA-15 simultaneously,and W₁₂Z₁₅/SBA-15 achieved 94.7%conversion of phenylacetylene and 88.4%selectivity of target product for the alkenylation of p-xylene with phenylacetylene.The catalytic performance of W₁₂Z₁₅/SBA-15 is superior to not only the single component solid acid catalysts,WO₃/SBA-15 and Zr O₂/SBA-15,but also W₁₂/Z₁₅/SBA-15 synthesized by impregnating the active ingredients,zirconium dioxide and tungsten trioxide,onto SBA-15 in sequence,which is attributed that the special impregnation method of W₁₂Z₁₅/SBA-15resulted in the formation of more composite oxide WO₃-Zr O₂ and produce more acid sites attributed to the strong interaction among them,with better catalytic performance obtained for alkenylation consequently.2.The optimal solid acid catalyst W₁₂Z₁₅/SBA-15-500 was synthesized under the optimum calcination temperature of 500 ^oC with the optimum molar ratio of zirconium dioxide to tungsten trioxide of 15/12.W₁₂Z₁₅/SBA-15-500 presented excellent catalytic properties for the alkenylation with 99.4%conversion of phenylacetylene and 92.3%selectivity of target product.Besides,W₁₂Z₁₅/SBA-15-500 possesses excellent renewability for the alkenylation.Consequently,it is persuasive to consider W₁₂Z₁₅/SBA-15-500synthesized by simple impregnation method as a promising candidate for the alkenylation.