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首页> 外文期刊>The journal of physical chemistry, C. Nanomaterials and interfaces >Mesoporous MCM-48 aluminosilica oxynitrides: Synthesis and characterization of bifunctional solid acid-base materials
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Mesoporous MCM-48 aluminosilica oxynitrides: Synthesis and characterization of bifunctional solid acid-base materials

机译：介孔MCM-48氮氧化铝硅：双功能固体酸基材料的合成和表征

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The preparation, structural characterization, and catalytic evaluation of novel solid acid-base mesoporous aluminosilica oxynitride materials are presented in this report. The materials were prepared by subjecting both direct (mixed-gel) synthesized and postsynthesis Al-grafted aluminosilicate MCM-48 materials to high-temperature nitridation, i.e., treatment with ammonia at elevated temperature. The properties of the mesoporous aluminosilica oxynitrides are mainly dependent on the preparation method and Al content. In general, aluminosilicates with high Al content were more susceptible to structural degradation during nitridation. Directly synthesized samples suffered greater structural degradation compared to Al-grafted samples of similar Al content. Oxynitrides derived from directly synthesized Al-MCM-48 exhibited higher amounts of nitrogen compared to materials derived from Al-grafted MCM-48, and in all cases, the nitrogen was incorporated into the aluminosilicate frameworks to generate various NHx species, including terminal NH2 and bridging NH groups and ammonium ions. The relative amount of terminal NH2 and bridging NH groups was dependent on the Al content and preparation history. The aluminosilica oxynitride materials exhibit both acidic and basic surface functionalities. The amount of acid sites and basic sites can be adjusted by controlling the Al content and by tuning the nitridation conditions. Basic sites predominate in all the mesoporous MCM-48 aluminosilica oxynitride materials', and the basicity was demonstrated by catalytic activity for the Knoevenagel condensation reaction.
机译：本报告介绍了新型固体酸基介孔氧化铝氧氮化硅材料的制备，结构表征和催化评价。通过对直接（混合凝胶）合成的和后合成的Al接枝的铝硅酸盐MCM-48材料进行高温氮化，即在升高的温度下用氨处理，来制备材料。介孔氧化铝氧氮化物的性质主要取决于制备方法和Al含量。通常，具有高Al含量的铝硅酸盐在氮化过程中更易于结构降解。与相似的铝含量的铝接枝样品相比，直接合成的样品遭受更大的结构降解。与衍生自Al接枝的MCM-48的材料相比，直接合成的Al-MCM-48的氧氮化物表现出更高的氮含量，并且在所有情况下，都将氮掺入铝硅酸盐骨架中以生成各种NHx物种，包括末端NH2和NH2。桥接NH基团和铵离子。末端NH 2和桥连NH基团的相对量取决于Al含量和制备历史。氮氧化硅铝材料同时具有酸性和碱性表面功能。可以通过控制Al的含量和调整氮化条件来调节酸位和碱位的数量。在所有介孔的MCM-48氮氧化硅铝材料中，碱性位均占主导地位，并且通过Knoevenagel缩合反应的催化活性证明了碱性。

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