CHAPTER 5: Gold-Based Catalysts

The discovery of the catalytic power of gold, always regarded as inert, dates back to the early 1990s. The keystone is the nanometric scale: only when bulk gold was found to be dramatically enhanced when downsized to nanometric particles did its extraordinary catalytic activity definitely come out and it still continues to show more of this peculiarity. This represented a breakthrough in chemistry, especially in organic synthesis, allowing catalyzed selective oxidations of various substrates to be carried out to give important chemicals under green conditions. Gold, alone or alloyed with a second metal, has turned out to be particularly effective in the selective oxidation of different alcohols, which can be tuned to their carbonylic and carboxylic derivatives. In this chapter, an overview of the aerobic oxidation of alcohols carried out with supported gold-based catalysts in the liquid phase is presented, with a particular focus on substrates of interest such as glycerol and allyl alcohol. Some vapor-phase processes worthy of mention are also included, plus a section introducing the main methods of preparation of gold-based catalysts and their characterization.