sentences:  The structure self-assembles in acidic aqueous solution and is the most stable structure of polyoxometalate catalysts.The first α-Keggin anion, ammonium phosphomolybdate ((NH4)3[PMo12O40]), was first reported by Berzelius in 1826.In 1892, Blomstrand proposed the structure of phosphomolybdic acid and other poly-acids as a chain or ring configuration.