Downstream processing of model polyalcohols by catalytic copolymerization reaction of CO2 and propylene oxide under subcritical conditions

CO2 can be used in copolymerization reactions as a C1 feedstock. It can be inserted into the polymer chain. Through the mechanism of Ring Opening Polymerization, propylene oxide is a suitable monomer for such reaction.


Active heterogeneous catalysts have been used for this study, zinc glutarate (ZnGA) and Zn-Co double metal cyanide (DMC). An exhaustive characterization of these catalysts and the obtained polymers have been done in these copolymerization reactions. They were analyzed by different techniques such as Fourier transform infrared spectroscopy (FTIR and FTIR with pyridine), Inductively Coupled Plasma Optical Emission Spectroscopy (ICP), Light scattering (with air and distilled water), Nitrogen-Physisorption, Size-exclusion chromatography (SEC), Scanning Electron Microscopy and Energy–dispersive X-ray spectroscopy (SEM-EDX), Thermogravimetric analysis-mass spectrometry (TGA-MS), X-ray photoelectron spectroscopy (XPS) and X-ray powder diffraction (XRPD). Several reaction conditions have been tested, demonstrating the effect of pressure, temperature, amount of catalyst, catalyst deactivation and catalyst preparation.

Figure 1. Copolymerization reaction among polypropylene glycol (PPG), propylene oxide (PO) and carbon dioxide (CO2).

High active DMC catalyst (2.5 kg polymer/g catalyst) could be synthetized obtaining 0.4 % of the byproduct cyclic carbonate. This reaction can be the base of a future chemistry to obtain polymers based in bio-alcohols.


María Pinilla de Dios – Johan Gadolin scholarship from Åbo Akademi (Turku, Finland) – Spanish Economy and Competitiveness Ministry (MINECO), Project Reference: CTQ2015-64892-R (BIOFRAHYNERY) and FEDER.

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