In-situ preparation of supported precious metal and metal oxide nanoparticles by nanoreactor flash pyrolysis
In-situ preparation of supported precious metal and metal oxide nanoparticles by nanoreactor flash pyrolysis
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DOI：
10.1016/j.micromeso.2009.02.019
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发表时间：
2009-06
影响因子：
5.2
通讯作者：
I. Gerlach;M. Kawase;K. Miura
中科院分区：
文献类型：
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作者：
I. Gerlach;M. Kawase;K. Miura
发展了一种在多孔载体材料上高效负载金属（氧化物）纳米粒子的新方法。以活性炭为介孔载体，制备了单晶二氧化钛和铑纳米粒子。前体金属醇盐首先吸附在载体上。然后通过快速热解在活性炭的孔内形成产物金属（氧化物）。应用高加热速率以快速达到其中前体的反应速率超过其从载体孔蒸发的速率的温度状态。用这种方法，负载金属（氧化物）纳米粒子上的介孔载体材料实现了高产率。在二氧化钛的情况下，产物负载量高达14重量%。对于铑，产品负载量约为。3wt.%获得了所制备的TiO 2纳米粒子为球形，粒径为5- 8 nm，几乎为单分散。颗粒是单晶的金红石相和金红石相。铑颗粒具有稍大的尺寸分布，范围从4至18 nm。产物形成仅发生在载体材料的孔中，因为吸附在外表面上的前体蒸发而不是反应。仅对于直径<4 nm的孔，载体孔体积因产物形成而减小。二氧化钛纳米粒子被证明是稳定的热活化迁移和烧结。通过改变热解温度可以有效地控制铑颗粒的晶粒尺寸。
A novel method for loading metal (oxide) nanoparticles on porous carrier materials at high yields was developed. Single-crystalline titania and rhodium nanoparticles were prepared within the mesopores of activated carbon which were used as a kind of nanoreactor. The precursor metal alkoxides were first adsorbed on the carrier. Product metal (oxide) was then formed within the pores of the activated carbon by flash pyrolysis. A high heating rate was applied in order to quickly reach a temperature regime where the reaction rate of the precursor exceeds the rate of its evaporation from the carrier pores. With this method, loading of metal (oxide) nanoparticles on mesoporous carrier materials was achieved at high yields. In case of titania, product loadings were as high as 14wt.%. For rhodium, product loadings of ca. 3wt.% were obtained. The TiO2nanoparticles formed were spheroidal and almost monodisperse with diameters of 5–8nm. The particles were single-crystalline of both anatase and rutile phases. Rhodium particles had a somewhat larger size distribution ranging from 4 up to 18nm. Product formation took place exclusively in the pores of the carrier material, since precursor that was adsorbed on the external surface evaporated instead of reacting. The carrier pore volume was reduced by the product formation merely for pores <4nm in diameter. Titania nanoparticles were shown to be stabilized against thermally activated migration and sintering. The crystallite size of rhodium particles was effectively controlled by variation of the pyrolysis temperature.