Ru–PPh3@porous organic polymer: efficient and stable catalyst for the trickle bed regioselective hydrogenation of cinnamaldehyde

Ru supported on the porous vinyl-functional triphenylphosphine organic polymer (Ru–PPh3@POP) as a heterogeneous catalyst for the selective hydrogenation of cinnamaldehyde (CAL) was synthesized. This catalyst, which combines the advantages of heterogeneous and homogeneous catalyst, showed much higher catalytic activity of continuous trickle bed hydrogenation of CAL than traditional inorganic material supported heterogeneous catalysts. The high efficiency of the Ru–PPh3@POP catalyst was attributed to the formation of the strong coordination bonds between the Ru species and the exposure phosphorus atoms on the surface of PPh3@POP support according to the results of EDS-mapping, 31P NMR, XPS analysis and HRTEM. Importantly, Ru species maintained their nanoparticles without further aggregation during the long-term reaction, and thus the catalyst exhibited a high conversion of CAL of 55% and selectivity towards cinnamyl alcohol (COL) of 63% even over 312 h of time on stream of hydrogenation of CAL. The ICP results of the reaction solution revealed that there was no Ru leaching from the PPh3@POP support during the continuous reaction process. This excellent catalytic activity and stability make it very attractive. Our approaches provide a methodology to expand the heterogenized homogeneous catalysts widely spread in exploitation in fine chemical industries.