Tailor-made MgF₂-based catalysts by sol-gel synthesis

In this paper, recent developments in the field of catalysts based on nanosized metal fluorides are presented with special focus on the exciting and promising magnesium fluoride systems. The majority of these new catalyst systems originate from the work of the authors based on the fluorolytic sol-gel synthesis of metal fluorides, which was developed by this group. They are selected in a way as to highlight the principles and prospects of this new approach to high-surface-area, strongly distorted metal fluorides. This new fluorolytic sol-gel route to metal fluorides opens, in the opinion of the authors, a very broad range of scientific and technical applications of the accessible high-surface-area metal fluorides. By combining fluorolytic and hydrolytic sol-gel synthesis, this approach can be further extended, also providing access to metal hydroxide fluorides or metal oxide fluorides. The different synthesis strategies as well as the catalytic applications of various MgF₂-based materials are described in detail in this review. Nanosized metal fluorides prepared by the fluorolytic sol-gel method represent an exciting new class of high-surface-area solid acid-base catalysts. A combination offluorolytic and hydrolytic sol-gel synthesis provides access to metal hydroxide fluorides or metal oxide fluorides.