Opportunities and prospects in the chemical recycling of carbon dioxide to fuels

This review analyses the opportunities and prospects in the chemical recycling of carbon dioxide to fuels, as a complementary technology to carbon sequestration and storage (CSS). It is remarked that the requisites for this objective are (i) minimize as much as possible the consumption of hydrogen (or hydrogen sources), (ii) produce fuels that can be easily stored and transported, and (iii) use renewable energy sources. From this perspective, the preferable option is to produce alcohols (preferably ≥C2) using solar energy to produce the protons and electrons necessary for the reaction of CO2 reduction. It is evidenced, however, that this is still a long-term objective, even if already some good advances in this direction exist. The different topics discussed in the review include CO2 (i) reverse water–gas shift and (ii) hydrogenation to hydrocarbons, alcohols, dimethyl ether and formic acid, (iii) reaction with hydrocarbons to syngas, (iv) photo- and electrochemical/catalytic conversion, and (v) thermochemical conversion. Other relevant options, such as the use of micro-algae or other bio-catalysis based processes, or the use of microwave and plasma processes are instead not addressed. Therefore, the area of carbon dioxide conversion to fuels and chemicals is a very active R&D sector, and it is anticipated that it represents a challenging possibility for companies to develop complementary strategies to CSS to reduce greenhouse gas emissions.