Prins condensation for the synthesis of isoprene from isobutylene and formaldehyde over sillica-supported H3SiW12O40 catalysts

The Prins condensation of isobutylene with formaldehyde over scillica-supported silicotungstic acid catalysts has been investigated. The catalysts were characterized via XRD, FTIR, Py-IR, NH3-TPD and TG–DSC techniques. It was found that the catalyst with 5 wt% silicotungstic acids loading exhibited the best isobutene conversion and isoprene selectivity, and excessive silicotungstic acid was not conducive to improve the catalytic performance. It was proposed that the concentration and strength of acid sites could affect the catalytic properties. An appropriate amount of weak Lewis acid sites were the active site for the condensation of isobutene with formaldehyde, and the medium-strong acid sites could cause the side reactions and coke deposits.