Composite catalyst for the photocatalytic isomerisation of norbornadiene to prepare quadricyclane and process for making the catalyst

A process of preparing a composite catalyst for photocatalytic isomerisation of norbornadiene to prepare quadricyclane, comprising the steps:

• (a) mixing a solution obtained by dissolving an organic photo-sensitizer in an organic solvent with a solid photocatalyst under sufficient stirring, wherein the weight ratio of the organic photo-sensitizer to the solid photocatalyst ranging from 0.5% to 20%, so that the organic photo-sensitizer is adsorbed onto a surface or a channel of the solid photocatalyst, wherein the solid photocatalyst is selected from WO3, Ta2O5 or SrTiO3;
• and the organic photo-sensitizer is selected from benzophenone, acetophenone, Michler's Ketone, tetraethyl Michler's Ketone, or diethyl Michler's Ketone;
• and
• (b) filtering off redundant solution and vacuum drying the solid photocatalyst which adsorbed the organic photo-sensitizer;
• wherein in the step (a), the organic photo-sensitizer is present in the solution in a concentration of 20% by weight, and the solid photocatalyst is dried at 100° C., and the stirring continues for 24 hours;
• and in the step (b), the vacuum drying is carried out at 100° C. for 5 hours.