Tuning Acid鈥揃ase Properties Using Mg鈥揂l Oxide Atomic Layer Deposition

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• 作者：David H. K. Jackson ; Brandon J. O鈥橬eill ; Jechan Lee ; George W. Huber ; James A. Dumesic ; Thomas F. Kuech
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2015
• 出版时间：August 5, 2015
• 年：2015
• 卷：7
• 期：30
• 页码：16573-16580
• 全文大小：410K
• ISSN：1944-8252

文摘

Atomic layer deposition (ALD) was used to coat 纬-Al₂O₃ particles with oxide films of varying Mg/Al atomic ratios, which resulted in systematic variation of the acid and base site areal densities. Variation of Mg/Al also affected morphological features such as crystalline phase, pore size distribution, and base site proximity. Areal base site density increased with increasing Mg content, while acid site density went through a maximum with a similar number of Mg and Al atoms in the coating. This behavior leads to nonlinearity in the relationship between Mg/Al and acid/base site ratio. The physical and chemical properties were elucidated using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), N₂ physisorption, and CO₂ and NH₃ temperature-programmed desorption (TPD). Fluorescence emission spectroscopy of samples grafted with 1-pyrenebutyric acid (PBA) was used for analysis of base site proximity. The degree of base site clustering was correlated to acid site density. Catalytic activity in the self-condensation of acetone was dependent on sample base site density and independent of acid site density.