Restructuring of the Lewis Acid Sites in Y-Modified Dealuminated Beta-Zeolite by Hydrothermal Treatment

作者：Fan Lin, Meijun Li, Stephen C. Purdy, Junyan Zhang, Yilin Wang, Sung Min Kim, Mark Engelhard, Zhenglong Li, Andrew D. Sutton, Yong Wang, Jian Zhi Hu, Huamin Wang · 发表于：ACS Catalysis · 年份：2024 · DOI：10.1021/acscatal.4c04135 · 被引用次数：15 · 研究领域：Zeolite Catalysis and Synthesis、Catalysis and Hydrodesulfurization Studies、Catalytic Processes in Materials Science

Yttrium-modified dealuminated Betazeolite (Y-BEA) represents a type of Lewis acid zeolite that has gained attention for its potential to efficiently catalyze the conversion of biomass-derived oxygenates. The structure of the Y active sites and their dynamics during biomass conversion reactions, which normally involve substantial amounts of water, necessitate thorough investigation for the rational design of more active and stable catalysts. Here, we conducted a study where a series of Y-BEA catalysts with different yttrium loadings (1–7 wt.%) were subjected to hydrothermal treatment (450 °C, 20% water) and investigated for their structural and catalytic activity changes through a combination of multiple characterizations and kinetic measurements. The number of acid sites of Y-BEA decreased without a change in acid strength following the hydrothermal treatment, which was confirmed by the results of acid site titration, infrared spectroscopy of probe molecules, and kinetic measurements for probe reactions (acetone aldol condensation). Structural analysis using X-ray diffraction (XRD), specific surface area measurement, X-ray absorption spectroscopy (XAS), and X-ray photoelectron spectroscopy (XPS) demonstrated that both the zeolite structure and the isolation status of the Y site remain intact after hydrothermal treatment. Further, the Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) spectra, thermogravimetric analysis (TGA), and operando 1 H and 29 Si magic...