Catalysts on a solid support are much easier to separate from the reaction mixture than homogeneous catalysts and can often easily be reused. Metal or metal oxide nanoparticle catalysts, for example, are often immobilized on powders. These powders are easy to separate after batch reactions but are not well suited to flow chemistry.

Anabel E. Lanterna, Juan C. Scaiano, and colleagues, University of Ottawa, ON, Canada, have used glass wool as a support for a range of metal and metal oxide nanoparticle catalysts, based on Pd, Co, Cu, Au, and Ru. Glass wool is inexpensive, widely available, and its fibrous structure allows it to be used in flow chemistry applications. In batch reactions, it can easily be removed from the reaction mixture using a pair of tweezers. The team used both non-silanized and silanized (i.e., covered with alkoxysilane molecules) glass wool and activated the materials using harsh acids or (3-aminopropyl)triethoxysilane. The type of glass wool was chosen depending on the metal or metal oxide to be immobilized.

The researchers used the prepared catalysts on glass wool supports in a variety of organic transformations, including both thermal and photochemical reactions, e.g., the dehalogenation of aryl halides, C–C coupling reactions, and click.chemistry reactions. The catalysts provided high yields and were reusable. According to the team, these results show the promise of glass wool as a catalyst support.

• Glass wool: a novel support for heterogeneous catalysis,
  Ayda Elhage, Bowen Wang, Nancy Marina, Maria Luisa Marin, Menandro Cruz, Anabel Estela Lanterna, Juan Tito Scaiano,
  Chem. Sci. 2018.
  https://doi.org/10.1039/c8sc02115e