Solid acid catalysts are largely used in several industrial processes, and the development of materials with high activity, selectivity and reusability is a subject of study of research groups around the world. The improvement of oxide acidity could be performed by phosphation with phosphoric acid but the investigation of phosphated niobia is still incipient. In this work, niobia was treated with phosphoric acid solutions to generate catalysts with higher esterification activity at mild condition. The phosphated catalysts were obtained and characterized by XRD, N2 adsorption, NH3 and pyridine chemisorption and FTIR, and were tested in the esterification of acetic acid with ethanol at 60 °C and RT. DFPT calculations indicated that H2PO4 group was the predominant phosphate species on the hydroxylated surface. Theoretical results also show that ethanol adsorbs preferentially at H2PO4 acidic sites on the phosphated catalyst as compared to acetic acid.

中文翻译：

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深入了解用 H3PO4 处理过的铌的磷酸盐种类

固体酸催化剂广泛用于多个工业过程，开发具有高活性、选择性和可重复使用性的材料是世界各地研究小组的研究课题。氧化酸度的改善可以通过用磷酸进行磷酸化来实现，但对磷化氧化铌的研究仍处于起步阶段。在这项工作中，用磷酸溶液处理氧化铌以在温和条件下生成具有较高酯化活性的催化剂。通过XRD、N2吸附、NH3和吡啶化学吸附和FTIR对磷酸化催化剂进行了表征，并在60℃和室温条件下对乙酸与乙醇的酯化进行了测试。DFPT 计算表明 H2PO4 基团是羟基化表面上的主要磷酸盐物质。