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

在含氮温敏聚合物存在下，氢还原铂酸，得到具有（100）面的铂纳米立方体，选择性为70%。这些Pt立方体被负载在氧化铝表面上，并在500℃下处理，它仍然保持立方结构。用该样品作NO-CH_4反应的催化剂时，其产物选择性与常规Pt/Al_2O_3催化剂（通常为111面）不同。到目前为止，只有模型反应已被报道，使用在真空系统中制备的单晶。这里，表面控制金属可用于实际反应。在高温下（1100℃），Al 2 O3形成α型，比表面积极低（1m^2/g），不能用于高温反应。本文介绍了以醇铝为羟基的反相微乳液法， 关于我们 胶束中的TED得到了很大的改善。凝胶在1,100℃下焙烧后，根据Ba含量的不同，成功地形成了各种细小的纳米颗粒;不含Ba的α氧化铝具有4 m^2/g，Ba/Al=1/48的α氧化铝具有75 m^2/g，Ba/Al=1/24的γ氧化铝具有156 m^2/g，Ba/Al=1/12的六铝酸钡具有98 m^2/g。用于反相微乳液法的含有有机物种的氧化铝前体在惰性气体下在1050-1350℃下焙烧。这种方法得到了被碳覆盖的γ-氧化铝纳米晶体，这防止了氧化物的烧结。1050℃焙烧后，样品的比表面积为35 m^2/g，晶粒尺寸仅为4 nm。这种独特的材料表面含有碳和氧化铝，可用于特殊用途（如电子导电材料）。最后可以在500-800℃下用空气或水处理该样品以恢复表面碳。令人惊讶的高表面积（320 m^2/g）γ氧化铝在800℃下稳定的第一次生产。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