Heteropolyacids (HPAs) are a class of acid catalysts widely used in various catalytic processes. Structurally, they are composed of a combination of heteroatoms (such as phosphorus, silicon, or germanium) and polyoxygenated metal clusters that are typically composed of transition metals like molybdenum, tungsten, or vanadium. HPAs exhibit unique physicochemical properties, including strong Brønsted acidity, redox potential, and thermal stability, making them highly versatile in catalysis.
