Polyol production with carbon dioxide

Until now, polyether polyols have been predominantly produced from oil derivatives. Co-operating with partners from industry and academia, Bayer MaterialScience has developed a process for utilising carbon dioxide for the synthesis process and incorporating it into the polymer backbone. This results in polyether polycarbonate polyols, which the company has now further developed for use in flexible foam products such as mattresses. In this way, carbon dioxide – a greenhouse gas that is abundantly available – can be put to use as a raw material. This opens up possibilities for conserving valuable crude oil resources.

"The results that have been obtained so far on the use of CO2 in slabstock foam are very promising indeed,” says Dr Hans-Georg Pirkl, an expert for flexible polyurethane foam at Bayer MaterialScience. "The properties of the foams we have been studying are equivalent to those of conventional grades.” The viscosity of the polyols is a little higher than that of standard products but processing on existing foaming machines is no problem.

The polyols with the carbon from CO2 as a synthesis building block are produced in a Bayer MaterialScience pilot plant that has been in operation at the Chempark Leverkusen site since the beginning of 2011. The CO2 comes from a power plant operated by project partner RWE. Other partners are RWTH Aachen University and the CAT Catalytic Center, which is run jointly by the university and Bayer. "This collaboration has significantly helped us to optimise the catalyst originally developed by Bayer. As a result, we can now get the chemically inert carbon dioxide molecule to react,” explains Dr Christoph Gürtler, who heads up several projects on the sustainable use of carbon dioxide. "On successful completion of the pilot phase, we plan to bring the first CO2-based grades to market in 2015. We are also working on developments for further polyurethane products.”

Apart from their suitability for high-quality plastics, CO2-based raw materials also make a multiple contribution to sustainability. The process saves the oil and energy that are needed in the conventional production of plastics, also naturally cutting the carbon dioxide emissions that would otherwise result. In addition, the power plant CO2 is used expediently and not simply emitted into the atmosphere.

Research scientists at RWTH Aachen University are currently investigating the new process in an ecoefficiency analysis to determine whether CO2 is indeed ultimately reduced. The first results are highly promising and look likely to back up this hypothesis.