Research and development of nano-sized metal catalysts whose metal crystal surface are controlled

在含氮热敏聚合物存在下，氯铂酸与氢气还原，制得具有(100)晶面的铂纳米立方体，选择性为70%。这些铂立方体负载在氧化铝表面，在500℃的温度下处理，仍然保持立方结构。当样品被用作NO-CH4反应的催化剂时，产物的选择性与传统的铂/氧化铝催化剂(通常具有111个表面)的反应不同。到目前为止，仅报道了使用真空系统中制备的单晶进行的模型反应。在这里，表面控制的金属可以用于实际反应。发现了一种制备具有(111)晶面的金字塔纳米晶体的新方法，在1100℃的高温下，氧化铝得到了比表面积极小(1m^2/g)且不能用于高温反应的α-型纳米晶。铝-醇盐为羟基…的反相微乳液法胶束中更多的TED得到了很大的改善。凝胶在1,100℃下焙烧后，可根据不同含量的不同形成不同的纳米颗粒，其中不含Ba的α-Al_2O_3为4m~2/g，Ba/Al=1/48的α-Al_2O_3为75m~2/g，Ba/Al=1/24的γ-Al_2O_3为156m~2/g，Ba/Al=1/12的六铝酸钡为98m~2/g。这种方法得到了覆盖在碳表面的纳米氧化铝，防止了氧化物的烧结。样品经1050℃焙烧后，比表面积为35m^2/g，但晶粒度仅为4 nm。这种独特的材料表面同时含有碳和氧化铝，可用于特殊用途(如电子导电材料)。该样品最终可以用空气或水处理，以在500-800℃时回收表面碳。首次获得了高比表面积(320m^2/g)稳定在800℃的伽马氧化铝。较少

Through chloplatinic acid reduction with hydrogen under the existence of N-containing thermo-sensitive polymers, platinum nano-cubes having (100) plane are produced with the selectivity of 70%. These Pt cubes are supported on alumina surface and treated at 500℃, which still keeps the cubic structure. When the sample is used as a catalyst for NO-CH_4 reaction, the product selectivity was found to be different from the reaction over the conventional Pt/Al_2O_3 catalysts (usually having 111 face). So far, only the model reaction have been reported using the single crystals prepared in a vacuum system. Here, the surface controlled metals can be used for the practically reaction. A new method was also found to prepare pyramid nano crystals having (111) face.At high temperature such as 1100℃, alumina get the alpha type whose surface area is extremely low (1m^2/g) and can not to be used for the high temperature reactions. The reverse micro-emulsion method where aluminium-alkoxide is hydroxyla … More ted in the micelles was improved a lot. After baking the gels at 1,100℃, various fine nano-particles are successfully formed depending on the Ba contents ; alpha alumina without Ba having 4 m^2/g, alpha alumina with Ba/Al=1/48 having 75 m^2/g, gamma alumina with Ba/Al=1/24 having 156 m^2/g, barium hexaaluminate with Ba/Al=1/12 having 98 m^2/g.Alumina precursor containing organic species used for the reverse micro-emulsion method was baked under the inert gases at 1050-1350℃. This method gave gamma-alumina nano-crystals covered by carbon, which prevented the sintering of the oxide. The surface area of the sample was 35 m^2/g after baking at 1050℃, but the crystal size was just 4nm. This unique material contains both carbon and alumina on the surface and can be used for the special purpose (such as electron conducting material). This sample can finally be treated with air or water to recover the surface carbon at 500-800℃. Surprisingly high surface area (320 m^2/g) gamma alumina stable at 800℃ was produced for the first time. Less