Photo-generation of cyclic carbonates using hyper-branched Ru–TiO2

Abstract

Anthropogenic CO₂ is the main contributor to the increased concentration of greenhouse gases in the atmosphere, and thus utilising waste CO₂ for the production of valuable chemicals is a very appealing strategy for reducing CO₂ emissions. The catalytic fixation of CO₂ with epoxides for the production of cyclic carbonates has gained increasing attention from the research community in search of an alternative to the homogeneous catalytic routes, which are currently being used in industry. A novel photocatalytic heterogeneous approach to generate cyclic carbonates is demonstrated in this work. Hyper-branched microstructured Ru modified TiO₂ nanorods decorated with RuO₂ nanoparticles, supported on fluorine-doped tin oxide (FTO) glass were fabricated for the first time and were used to catalyse the photo-generation of propylene carbonates from propylene oxides. Propylene carbonate was used as a reference for cyclic carbonates. The photo-generation of cyclic carbonates from epoxides and CO₂ was carried out at a maximum temperature of 55 °C at 200 kPa in a stainless steel photoreactor with a quartz window, under solar irradiation for 6 h. The best performing photocatalyst exhibited an estimated selectivity of 83% towards propylene carbonates under the irradiation of a solar simulator.