CO2Chem focuses on Carbon Dioxide Utilisation, CDU. CO2 emissions are a big problem and need to be reduced to combat climate change. One method of doing this is by using Carbon Capture and Storage (CCS). CCS in basic terms involves capturing emissions at source (usually a power station), separating out the CO2, then storing the gas by pumping into geological reservoirs. CDU takes the carbon dioxide and uses it to create new products such as green transport fuels, methanol, memory foams, plastics for cars, pharmaceuticals, cement and building materials all from CO2. They do this by reacting the CO2 with other chemicals using a catalyst and energy. This energy comes from renewables so it doesn’t use up more fossil fuels.
CCS is costly but will result in lower CO2 emissions. It is estimated that CCS will increase the amount of fuel energy needed in a coal fired power station by 25-40%. By developing methods of using the CO2 captured as a chemical feedstock, costs can be offset. CCS represents a loss of carbon (it is stored under the sea); something that with the decreasing amount of petrochemical reserves should be avoided. By using CDU instead we could ease our reliance as a society on petrochemical based feedstocks for the production of commodity chemicals by taking a more environmentally sound approach to chemicals production using CO2 as a feedstock.
We can use CO2 to make a range of useful products either by chemical or biological conversion or we can use it directly. CO2Chem is interested in converting the CO2 into new products.
What is CO2Chem aiming for?
The principle aim of this GC Network is to utilize CO2 as a sustainable feedstock to produce a diverse range of chemical products.
A combined strategy for the reduction of CO2 emissions and producing sustainable chemical feedstocks is certainly a Grand Challenge. The network addresses ways in which CO2 can be captured (chemical, mechanical and biological) and then transformed into commercially valuable products. We consider all options available including the use of CO2 from existing Carbon Capture & Storage technologies and biomass and the integration of catalysts and sustainable energy resources. We look at individual synthetic procedures, the whole process and also the life cycle analysis.
In simplest terms, as a global community we are confronted with a very serious problem: our demand for materials and energy is rapidly outstripping our environment’s ability to provide raw materials. Unprecedented and rapidly growing demand for fossil‐based resources, coupled with diminishing reserves, geopolitical uncertainty and the accelerated threats of climate change are all factors that make the current petrochemical industry unsustainable. Using the carbon molecule from CO2 as a resource could be a solution this problem. CO2 is available from both free (waste and atmospheric) and fixed (biomass) sources.
The UK has set a target of reducing greenhouse gas (predominantly CO2) emissions by 80% by 2050 and a reduction of at least 26% in CO2 emissions by 2020. A whole range of initatives will be needed to reach this target including improving manufacturing processes, increasing insulation in our homes and using more renewable or nuclear energy. CCS is a good way of reducing CO2 emissions in the short to medium term especially from coal and gas powerstations. However it is costly and still needs further research. If CO2 utilisation is used in parallel to CCS it can reduce the need to store some of the CO2 and provide and income stream to offset costs.
What challenges need to be overcome to make CO2 utilisation work?
A number of methods have been proposed for the conversion of CO2 into chemicals but many rely on extremes of temperature and pressure for success.
- Catalytic methods for CO2 utilisation which will enable reactions under far milder conditions will therefore become increasingly important. To use this method of remediation requires additional feedstocks, particularly hydrogen. Therefore, methods of identifying the sustainable production of large volumes of hydrogen from biomass will also be needed.
- We will need to look at sustainable energy production and conservation in the whole process. Energy integration will be essential if an economically viable product is to be achieved.
- Nature, via photosynthesis, provides a wide range of potential feedstocks that differ significantly in their composition from hydrocarbon‐based petrochemicals. Bio‐based feedstocks can either be converted into platform chemicals (ethylene, propylene, acrylonitrile, etc.) for the direct replacement of petrochemically derived feedstocks or new and alternative processes can be developed that retain some of the intrinsic advantages of biomass including chirality and biodegradability. The challenge in this case would be the development, at scale, of new chemistries and processes that can deliver platform molecules from oxygenated feedstocks in high purity.
The alternative route, which is in many ways inspired by nature, could in principle be considered as =‘accelerated fossilisation’. The idea is very simple, i.e. “the direct production of known hydrocarbon based platform chemicals directly via the activation of CO2”. In this case the challenge is overcoming the energetic barrier to allow the efficient formation of C‐C bonds in a controllable way whilst reducing the overall content of oxygen in the products.
What are the main keys to success?
Key to the success of both approaches is the development of new families of catalysts that are able to operate under the highly oxygenated conditions imposed by the feedstock:
- In the case of a biologically mediated sequestration of CO2, we must design robust methods for reducing the raw feedstock to much more simple hydrocarbons that industry can deal with.
- In the case of accelerated fossilisation, we must invent new transformations and catalysts that will facilitate the stepwise construction of simple hydrocarbons from C1 fragments.
Current catalyst technologies are not sufficient to realise these goals and a step change in the understanding and design of complex catalytic processes at the molecular level is required to provide general approaches to the new chemical transformations that are required.
One of the key drivers in the success of carbon dioxide utilisation will be the efficient integration of energy resources in order to make the processes economically viable. While some transformations of CO2 have been shown to be exothermic, many require a large amount of energy to overcome the thermodynamic limitations. Another factor to influence the vision of the Network is the chemistry that can be achieved using CO2 as a precursor. While some chemistry exists, it is envisaged that new C1 chemistry will need to be developed and that the materials produced are not necessarily those currently used in processes. Hence, the chemicals industry will experience a step change in its approach to chemical synthesis.