The use of carbon dioxide (CO2) with renewable energies may seem a novelty with most studies and investments in the area of CO2 utilisation focusing primarily on fuels. The big potential of CO2 as a renewable and sustainable carbon feedstock for the chemical industry is overlooked. Yet as a report by nova-Institute puts it, organic chemistry and polymer production cannot "decarbonise" simply because carbon is the key molecule. Instead, a "recarbonistation" with green carbon is needed.
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For many, the use of carbon dioxide (CO2) with the help of renewable energies is still a bit of a novelty. According to Germany-headed nova-Institute GmbH, a private and independent research institute that offers research and consultancy with a focus on bio-based and CO2 -based economy, most studies, and investments currently underway are in the area of CO2 utilisation with a focus primarily on fuels.
This “rather narrow-minded point of view” misses the big potential of CO2 as a renewable and sustainable carbon feedstock for the chemical industry of the future. The organic chemistry and polymer production cannot decarbonise, simply for the reason that carbon is the key molecule in this area. Given this minor constraint, a renewable alternative to fossil feedstocks is needed.
As it happens a large number of high-value chemicals and especially polymers can be produced from CO2 in different ways. Addressing this information gap, nova-Institute published in March 2018 the first worldwide technology study on this topic: “Carbon dioxide (CO2) as a chemical feedstock for polymers – technologies, polymers, developers and producers” which has now been updated comprehensively.
Polymer production pathways
The study investigates from a technological point of view which polymers can be produced from CO2 and provides an overview of the polymers that have already been developed, produced and marketed and by which companies. The report goes into detail about various opportunities to produce building blocks and polymers based on CO2 via different pathways; chemical, biological and electrochemical.
Chemical catalytic processes are used to produce chemicals such as aromatic phosgene-free polycarbonates (PC) or aliphatic polycarbonates (APC) like polypropylene carbonate (PPC), polyethylene carbonate (PEC), polylimonene carbonate (PLimC) and polyurethane resins (PUR) that are synthesised with CO2-based polyols.
Biotechnological approaches include fermentation of CO2 or CO2-rich syngas that generally contains carbon monoxide (CO), CO2 and hydrogen (H2) via microorganisms like bacteria, algae, and cyanobacteria that lead to building blocks such as lactic acid or succinic acid, from which polymers like polylactic acid (PLA) or polybutylene succinate (PBS) can be made.
Polyhydroxyalkanoates (PHAs) are polymers which can be directly derived by fermentation of CO2 without any intermediate building blocks.
Electrochemical pathways, for example to monoethylene glycol (MEG), which is used for the production of polyethylene terephthalate (PET), are also described in the report. Additionally, the use of CO2-based methanol as a feedstock is an alternative route to produce olefins via an already established process, the “Methanol to Olefin (MTO)” process.
Also, a huge potential lies in the so-called “Blue Crude” oil substitute that can be produced via a Fischer-Tropsch synthesis from syngas and directly substitute crude oil in a refinery for the production of conventional fuels, chemicals, and polymers as drop-ins based on a renewable carbon feedstock.
Over 160 000 tonnes CO2-derived polymers on the market
First pilot demonstration and commercial production plants are already installed in which CO2 is used either directly as a building block for polymers or indirectly in combination with other, non-CO2-derived monomers to obtain a large array of plastics with tailor-made properties.
The report describes at least 30 companies from Asia, Europe, and North America are already working on a large number of CO2-based polymers and plastics – leading to a total of more than 160 000 tonnes of CO2-based polymers already on the market.