Laboratory for Catalysis Engineering, School of Chemical and Biomolecular Engineering, The University of Sydney, Sydney, New South Wales 2006, Australia.
ARC Centre of Excellence for Functional Nanomaterials, School of Chemical Engineering, The University of New South Wales, Sydney, New South Wales 2052, Australia.
J Phys Chem Lett. 2022 Jan 20;13(2):486-491. doi: 10.1021/acs.jpclett.1c03489. Epub 2022 Jan 10.
The surface acidity and local coordination environment of zeolites and amorphous silica-aluminas (ASAs) can promote acid-catalyzed C-H activation in many important hydrocarbon conversion reactions. Acid sites generated by penta-coordinated Al species (Al) can lead to enhanced acidity and changes in the surface coordination. We evaluated the potential of flame-derived ASAs with enriched Al for C-H activation using hydrogen/deuterium (H/D) exchange with benzene-. With increasing Al content of ASAs, the exchange rate increased, whereas the activation energy () slightly decreased due to the enhanced Brønsted acidity. The ASAs exhibited significantly higher exchange rates and lower values than the sol-gel-derived ASAs and zeolite H-ZSM-5. The superior activity is attributed to the fact that more oxygen coordinated with Al species on flame-made ASAs, which can act as acceptors for D, enhancing the deuterium displacement. These findings could offer a valuable alternative strategy for tailoring high-performance solid acids to promote hydrocarbon conversion reactions.
沸石和无定形硅铝酸盐（ASAs）的表面酸度和局部配位环境可以促进许多重要烃类转化反应中的酸催化 C-H 活化。五配位 Al 物种（Al）生成的酸位可以导致酸度增强和表面配位的变化。我们使用苯-H/D 交换评估了富含 Al 的火焰衍生 ASAs 用于 C-H 活化的潜力。随着 ASAs 中 Al 含量的增加，交换速率增加，而由于 Brønsted 酸度增强，活化能（Ea）略有降低。与溶胶-凝胶衍生的 ASAs 和沸石 H-ZSM-5 相比，ASAs 表现出更高的交换速率和更低的 Ea 值。优越的活性归因于火焰制造的 ASAs 上更多的氧与 Al 物种配位，氧可以作为 D 的受体，增强氘的取代。这些发现为定制高性能固体酸以促进烃类转化反应提供了有价值的替代策略。
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