Solventless synthesis of propylene carbonate catalysed by chromium-salen complexes: Bridging homogeneous and heterogeneous catalysis

Various chromium complexes were synthesised and tested concerning their catalytic performance in the synthesis of propylene carbonate from carbon dioxide and propylene oxide. The most active complexes were immobilised on a silica support and tested in the same reaction. Different immobilisation methods were applied (figure). The coordinatively-bound complexes showed low stability and a very strong deactivation during reuse, whereas the corresponding covalently-bound complexes hardly showed any chromium leaching during catalyst recycling experiments.