The plastics industry is beginning to use carbon dioxide – now widely considered as a pollutant – as a precursor for making a new generation of materials. Lou Reade reports.
Ever since it was given a central role in climate change, carbon dioxide has been the bad guy. A myriad of schemes exist to remove – or sequester – it from the atmosphere. Then, there is the question of what to do with it. One idea, which is growing in importance, is to feed it back into the manufacturing industry – where it can be used as the precursor for fuel or even raw materials.
Several plastics companies have already begun to use carbon dioxide as a raw material to make a new generation of plastics – especially polyurethanes. US-based Novomer, for example, recently commercialised a process that converts carbon dioxide into polypropylene carbonate (PPC) polyols for use in polyurethane formulations in adhesives, coatings, sealants, elastomers and rigid and flexible foams. It is initially offering two products – 1000 and 2000 molecular weight grades.
The material, called Converge, replaces conventional petroleum-based polyether,polyester, and polycarbonate polyols. It based on the co-polymerisation of carbon dioxide and epoxides, and the resulting products contain more than 40% by weight of CO2.
Incorporating the new polyols into existing formulations produces foams with higher tensile and tear strength, and increased load bearing capacity, according to Novomer.
“This is a significant milestone in the commercial development of this breakthrough technology,” said Peter Shepard, chief business officer for Novomer. “Our scale-up and product launch validates the robustness of our manufacturing technology and the strong interest we’ve received from a wide range of applications in the polyurethanes market.”
So far, the materials have been used commercially in coatings, adhesives, sealants, and elastomer applications.
The company has also confirmed two European distributors: Quimidroga will act in Spain, Portugal and Turkey, while Reschem Italia will distribute the materials in Italy.
Meanwhile, Bayer MaterialScience is to invest E15 million building a production line at its Dormagen site in Germany, which will use CO2 to produce a precursor for premium polyurethane foam.
The ‘Dream Production’ project aims to launch its first CO2-based polyols onto the market in 2016. The line will have an annual production capacity of 5,000 tonnes.
Bayer says the new polyols will have at least the same level of quality as conventionally manufactured materials, but with a more sustainable impact. Using CO2 as a building block allows the process to run with a reduced amount of propylene oxide – the petroleum-derived raw material from which polyols are made.
The production process has been developed in collaboration with partners in industry and academia. Bayer discovered the catalyst that brings about the chemical reaction, and developed it with the CAT Catalytic Center, a research facility in Aachen, Germany. The process was tested in a pilot plant at its Leverkusen site as part of the publicly funded Dream Production research project.
The new polyol is used to make polyurethane foam, which is typically used in upholstered furniture, shoes and automotive parts, and to insulate buildings and refrigeration equipment.
“The first major field of application is likely to be mattress production,” said Karsten Malsch, Dream Production project manager at Bayer MaterialScience.
These examples use polypropylene carbonate to make polyurethane – usually in the form of foam. But PPC has also been used in a blended plastic with similar properties to ABS, a commonly used material.
A project funded by the German Research Ministry, including partners such as Siemens and BASF, spent three years developing a blended plastic with similar physical properties to ABS. The main element is polyhydroxybutyrate (PHB), which is made from renewable raw materials such as palm oil and starch. But PHB is quite brittle, so polypropylene carbonate from BASF is added to make it softer. The PPC – as in earlier cases – is made from carbon dioxide obtained from power plant emissions.
More than 70% of the material is made of green polymers. It has been moulded into a typical ‘ABS’ part – a vacuum cleaner cover – by Bosch-Siemens-Hausgeräte (BSH). The researchers are now investigating whether they can replace other types of plastic used by BSH with CO2-based composite materials.
But the best example of converting greenhouse gases into usable products may be that offered by Newlight Technologies. Its combines the two bogeymen of global warming – carbon dioxide AND methane – and catalyses their reaction together into a plastic called Air Carbon. The material, similar to a bio-based plastic called polyhydroxyalkanoate (PHA), can replace conventional plastics such as polyethylene and polypropylene.
This year, the company began producing the material in commercial quantities at its plant in California, USA. Furniture manufacturer KI is incorporating the material into two of its product lines, while telecoms company Sprint has used it to make mobile phone cases. This autumn, Dell will use the material to make packaging sleeves for its Latitude notebooks.
“By using carbon that would otherwise be in the air we are breathing right now, AirCarbon turns everyday goods into products that actually improve the environment,” said Mark Herrema, CEO of Newlight. “Combined with a cost profile that is more favorable than oil-based plastics, AirCarbon has the potential to change the world.”
It’s not just plastics that benefit from using carbon dioxide as a feedstock. Researchers in Poland are looking into how the gas could be used to create nanomaterials with ‘unprecedented properties’.
Scientists at the Polish Academy of Sciences and Warsaw University of Technology say that their highly porous nanomaterials could be used to store gases, or as catalysts or sensors.
“Using carbon dioxide as a building block, we were able to construct a highly porous and luminescent material,” said Kamil Sokołowski, a doctoral student at the Polish Academy of Sciences.
He believes that the material could be used to create luminescent diodes that have far higher efficiency than those made from traditional materials.
“Carbon dioxide has for years been used in industrial synthesis of polymers, but there have been very few research papers reporting fabrication of inorganic functional materials using CO2,” he added.
Further research at the two institutes has shown that the materials can be transformed into zinc oxide aerogels. Other potential applications are related to semiconducting properties of zinc oxide – so might find future use in photovoltaic cells or in semiconductor sensing devices.
The research, carried out in cooperation with the universities of Cambridge and Nottingham, were published in the journals Angewandte Chemie and Chemical Communications.