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

在含n热敏聚合物存在的条件下，通过氢还原氯铂酸制得具有（100）平面的铂纳米立方体，其选择性为70%。将这些Pt立方体支撑在氧化铝表面，并在500℃下处理，仍然保持立方体结构。将该样品作为NO-CH_4反应的催化剂，发现其产物选择性与常规Pt/Al_2O_3催化剂（通常为111面）上的反应不同。到目前为止，只报道了在真空系统中制备单晶的模型反应。在这里，表面受控金属可用于实际反应。还发现了一种制备具有（111）面锥体纳米晶体的新方法。在1100℃等高温下，氧化铝得到α型，其表面积极低（1m^2/g），不能用于高温反应。以铝醇盐为羟基的反相微乳液法得到了很大的改进。经1100℃烘烤后，根据Ba含量的不同，成功地形成了不同的纳米颗粒；没有Ba的氧化铝有4 m^2/g， Ba/Al=1/48的氧化铝有75 m^2/g， Ba/Al=1/24的氧化铝有156 m^2/g， Ba/Al=1/12的六铝酸钡有98 m^2/g。在1050 ~ 1350℃的惰性气体下，对用于反微乳液法的含有有机物质的氧化铝前驱体进行烘烤。这种方法得到了碳覆盖的γ -氧化铝纳米晶体，防止了氧化物的烧结。经1050℃烘烤后，样品的表面积为35 m^2/g，晶粒尺寸仅为4nm。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）。该样品最终可在500-800℃用空气或水处理以回收表面碳。首次制备出在800℃下稳定的高表面积(320 m^2/g) γ氧化铝。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