CO2 as a C1–building block
Carbon dioxide has been used for decades as a raw material for the production of urea, salicylic acid, ethylene (propylene) carbonate, as well as methanol from a blend of CO and CO2. However, it still remains a tremendous challenge for obtaining a wide range of chemical structures as CO2 displays limited reactivity in comparison with other C1 molecules in use, e.g. carbon monoxide and phosgene.
Addressing the issue of emission excess of CO2 in the atmosphere has increased notably the interest in CO2 as a C1-building block. Moreover, nowadays it makes sense to recycle a waste to fulfill sustainability criteria. Turning CO2 to a valuable and renewable feedstock offers also an alternative for mastering the use of fossil fuels, thereby impacting on anthropogenic emission. Nevertheless, decarbonization of energy supply should be integrated to avoid penalty associated with the stability of CO2.
This presentation will discuss the main reaction channels from CO2 to value-added chemicals. Some of them have already been implemented as environmentally innovative technologies while others have just been designed. Basically, these reactions take place by acid-base and redox mechanism, respectively. Formally, CO2 either retains its oxygen atoms or is deoxygenated. To the purpose, catalysis is a favored methodology, which may be associated with photo- and electrochemical activation. There are challenges to boost catalyst performance (activity, stability, selectivity) and shift favorably thermodynamics equilibria. As a matter of fact, major breakthroughs are still a few although there is market demand for fuels, polymers, and chemical intermediates produced from renewables.
For entering the value chain of the production of chemicals, CO2 as a carbon resource has to be defunctionalized at the opposite of fossil carbon resource. A better understanding of the CO2-based chemistry is on the track for evaluating how much CO2 could be converted into chemicals.