FTIR study of hydration of dodecatungstosilicic acid

The isomerization of 2‐methyl‐2‐pentene has been studied on boron phosphate (BP) catalysts with P/B ratios from 0.8 to 1.6 and at various reaction temperatures and contact times. Double‐bond shift occurs on the compositions with P/B of 1.0 and less, while methyl shifts occur on samples with P/B of 1.2–1.6, demonstrating the presence of strong acidity on the latter solids. Ammonia chemisorption and proton MAS NMR is employed to provide supplementary evidence of the variation in acidity with composition. Although BP of P/B < 1 contains predominantly Lewis acid sites, 2‐methyl‐2‐pentene isomerizes through carbocations, which are formed on the strong Brønsted acid sites on BP with P/B > 1.