Propylene oxide (PO) was used as solvent for its copolymerization with CO2 using zinc glutarate catalyst, producing high molecular weight polycarbonate in an exceptionally high yield never achieved before. Both the PO used as solvent and the excessive CO2 are fully recoverable, respectively, and re-usable for the next batches of their copolymerization, indicating that this is a clean, green polymerization process to fix CO2 into the polycarbonate. The product yield was further improved in the large-scaled copolymerization. Zinc glutarate was prepared through several synthetic routes and, however, one from zinc oxide exhibited the highest catalytic activity in the copolymerization.