Valorisation of CO2 from biogas

The growing environmental concerns correlated with the carbon dioxide (CO2) emission have led to the development of technologies to diminish the CO2 released into the atmosphere, aiming to mitigate climate change. On the other hand, these technologies can help in developing circular economy, that valorise CO2 as raw material for chemicals and fuel production through recycling.

In this framework, the valorisation of CO2 in a production chain that exploits organic wastes, recycling them to obtain biogas, can be considered a valuable step towards a complete circular economy. Biogas is obtained through the anaerobic digestion with methanogen or anaerobic organisms inside a closed system, or through the fermentation of biodegradable materials. It is mainly composed of CH4 and CO2, and it is used for heating purpose or in a gas engine to convert the chemical energy into electricity and heat. CO2 sequestration from the CH4 and CO2 mixture using ionic liquids can be considered a fast energy-efficient method to obtain biogas with lower CO2 concentration and consequently higher calorific power, while, at the same time, producing a pure stream of CO2. The CO2 sequestered by ionic liquids can in turn be released and electrochemically converted into valuable products (e.g. CO, formic acid, methanol…), by using highly selective and efficient electro-catalysts.