Photocatalytic-controlled olefin isomerization over WO3-x using low-energy photons up to 625 nm

WO3-x (W-1) was used to achieve controllable photoisomerization of linear olefins without substituents under 625 nm light irradiation. Thermodynamic and kinetic isomers were obtained by regulating the carbon chain length of the olefins. Terminal olefins were converted into isomerized products, and the internal olefin mixtures present in petroleum derivatives were transformed into valuable pure olefin products. Oxygen vacancies (OVs) in W-1 altered the electronic structure of W-1 to improve its light-harvesting ability, which accounted for the high activity of olefin isomerization under light irradiation up to 625 nm. Additionally, OVs on the W-1 surface generated unsaturated W5+ sites that coordinated with olefins for the efficient adsorption and activation of olefins. Mechanistic studies reveal that the in situ formation of surface pi-complexes and p-allylic W intermediates originating from the coordination of coordinated unsaturated W5+ sites and olefins ensure high photocatalytic activity and selectivity of W-1 for the photocatalytic isomerization of olefins via a radical mechanism. (C) 2021, Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.

Automated summary

Controllable photoisomerization of linear olefins without substituents under 625 nm light irradiation was achieved using WO3-x (W-1). By regulating the carbon chain length of the olefins and utilizing oxygen vacancies in W-1, valuable pure olefin products were obtained through this process. The high activity of olefin isomerization under light irradiation was attributed to the altered electronic structure of W-1 and the generation of unsaturated W5+ sites on the W-1 surface.