Solid catalyst material, especially silica-alumina material with Brønsted acidity plays a dominant catalytic role in the petrochemical and biorefining industries. The development of next generation of silica-alumina materials is beneficial both economically and environmentally. In this research, a straightforward and cost-effective synthesis method will be demonstrated in order to synthesize silica-alumina materials with enriched surface AlV-based Brønsted acidity.
For characterization of solid materials and understanding the corresponding structure-acidity-activity relationship, in this research, the Solid-State Nuclear Magnetic Resonance Spectroscopy (ssNMR) was largely utilized. By the application of multinuclear ssNMR spectra, such as one-dimensional single pulse 1H, 27Al, 29Si, 31P ssNMR; 1H-27Al TRAnsfer of Populations in DOuble Resonance (TRAPDOR) NMR; two-dimensional 27Al-27Al Multiple Quantum (MQ) NMR; 1H-27Al Heteronuclear correlation (HETCOR) NMR, the local structure of the solid catalyst material was visualized. And the spectra information showed that the silanol linkage density and AlV-BAS density can be regulated by the stepwise addition cycles of Si species. To the best of our knowledge, this is the first time that the surface active AlV-based Brønsted acid site has been prepared on a mesoporous silica-alumina material using simple and cheap approach.
In the test reaction of catalytic biomass 1,2-propanediol conversion, the AlV based Brønsted acid site showed higher efficiency compared to that of AlIV based Brønsted acid site. This finding presents promising opportunities for the large-scale industrial implementation of mesoporous silica-alumina with AlV-BAS, as it can potentially enhance the catalytic activity and selectivity of the material in various chemical reactions.