Template Synthesis and Catalysis of Metal Nanowires in Mesoporous Materials

在介孔二氧化硅FSM-16(孔径2.7 nm)和有机-无机杂化介孔材料HMM-1(孔径3.1 nm)中合成了过渡金属纳米线，并对其表征、物化性能及催化性能进行了研究。本研究项目取得了以下成果。1.浸渍铂盐后干燥FSM-16分子筛，并用甲醇代替异丙醇作为光还原的还原剂，促进了中孔中长纳米线的形成。2.Pt和Rh纳米线是在HMM-1中制备的，后者是Rh纳米线的第一个例子。3.首次在HMM-1中成功地制备了双金属铂-Rh和铂-钯纳米线。双金属纳米线由合金微晶组成，具有独特的纳米项链结构。4.在丁烷氢解反应中，铂纳米线/FSM-16催化剂的转化率是铂纳米粒子/FSM-16催化剂的36倍。这是一个有趣的例子，表明铂催化剂中纳米线的形状大大增强了其催化功能。另一方面，Pt-Rh纳米线/FSM-16对异丁烷具有较高的选择性。铂-钯纳米线/HMM-1比铂纳米线/HMM-1具有更高的磁化率，这与合金相的纳米线结构有关。5.在苯和乙醇的混合溶剂中，用季铵盐处理铂纳米线/FSM-16，从FSM-16中提取铂纳米线。虽然其他小组报道了通过用强酸或强碱溶解介孔材料来回收一些金属纳米线，但我们的方法是在不分解介孔材料的情况下化学提取金属纳米线。

Transition metal nanowires were synthesized in mesoporous silica FSM-16 (pore diameter 2.7nm) and organic-inorganic hybrid mesoporous material HMM-1 (pore diameter 3.1 nm), and their characterization, physical and chemical properties, and catalysis were studied. The following results were obtained in this research project. 1. Drying FSM-16 after impregnation of Pt salts and using methanol in place of 2-propanol as a reductant in photoreduction enhance the formation of long nanowires in the mesopores. 2. Pt and Rh nanowires are prepared in HMM-1 ; the latter is the first example of Rh nanowires. 3. We have succeeded in the first preparation of bimetallic Pt-Rh and Pt-Pd nanowires in HMM-1. The bimetallic nanowires consist of alloy crystallites with a unique nano-necklace structure. 4. Pt nanowire/FSM-16 shows 36 times higher turnover frequency than Pt nanoparticle/FSM-16 in hydrogenolysis of butane. This is an interesting example indicating that the shape of nanowire in Pt catalysts greatly enhances their catalytic function. On the other hand, Pt-Rh nanowire/FSM-16 gives a high selectivity to isobutane. Pt-Pd nanowire/HMM-1 shows higher magnetic susceptibility than Pt nanowire/HMM-1, which is attributable to the nanowire-structure of alloy phase. 5. Pt nanowires are extracted from FSM-16 by treating Pt nanowire/FSM-16 with quaternary ammonium salts in a mixture of benzene and ethanol. Although other groups reported that some metal nanowires were recovered by dissolving mesoporous materials with strong acids or bases, our method is chemical extraction of metal nanowires without decomposing the mesoporous materials.