Nanoparticles and Catalysis || Colloidal Nanoparticles Stabilized by Surfactants or Organo-Aluminum Derivatives: Preparation and Use as Catalyst Precursors
✍ Scribed by Astruc, Didier
- Publisher
- Wiley-VCH Verlag GmbH & Co. KGaA
- Year
- 2007
- Tongue
- German
- Weight
- 754 KB
- Edition
- 1
- Category
- Article
- ISBN
- 3527315721
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✦ Synopsis
During the last few decades a considerable body of knowledge has been gained regarding the synthesis, characterization, and potential application of nanosized metal particles [1 -26] . Highly dispersed mono -and bi -metallic colloids have been used as precursors for a new type of catalyst that is applicable both in the homogeneous [27] and heterogeneous phases [28] . Besides the obvious applications in chemical catalysis, recent studies have examined the great potential of nanostructured metal colloids as fuel cell catalyst precursors [29,30] . To date, two major industrial applications of nanocatalysis have emerged from the benches of the research laboratories: Headwaters NanoKinetix and Degussa have developed and patented [31] a direct synthesis method for the production of H 2 O 2 from hydrogen and oxygen using size -defi ned nanoclusters of palladium (6 nm) anchored to a catalyst support. This simplifi ed process offers multiple advantages over the current multi -step cost -intensive anthraquinone process: It is environmentally friendly, eliminating the use of a toxic substance while producing only water as a by -product, and has the potential to reduce production costs from 25 -35 cents per pound to less than 15, while reducing the capital cost required for large -scale H 2 O 2 production plants by up to 50%.
Even more spectacular results in terms of the increasing importance of nanocatalysis for bulk industrial processes have recently been reported by Kuipers and de Jong [32,33] . By dispersing metallic cobalt nanoparticles of specifi c sizes on inert carbon nanofi bers the authors were able to prepare a new nano -type Fischer -Tropsch catalyst. A combination of X -ray absorption spectroscopy, electron microscopy, and other methods has revealed that zerovalent cobalt particles are the true " active centers " which convert CO and H 2 into hydrocarbons and water. Further, a profound size effect on activity, selectivity, and durability was observed. Via careful pressure -size correlations, Kuipers and de Jong have found that or cobalt particles of 6 or 8 nm are the optimum size for Fischer -Tropsch catalysis. The Fischer -Tropsch process (invented in 1925 at the Kaiser -Wilhelm -Institute for 49