Novel intensified processes for CO2 capture and conversion to methanol – CO22MeOH
Cement industry has been always among the largest CO2 emission sources, with almost 5–7% of global CO2 emissions caused by cement plants. Therefore, it represents an ideal sector for the implementation of CO2 capture technologies, considering also that the CO2 concentration in the flue gases is particularly high (14-33%). As carbon is a fundamental building block, it is desirable to further develop processes to recycle captured CO2 and use it as carbon source for the production of fuels and/or chemicals, taking industry a step closer to a true circular economy. In this context, the main goal of CO22MeOH is to develop a highly intensified, efficient integrated process for the capture of CO2 from the flue gases of cement plants and its further hydrogenation to methanol. The proposed value chain will be assessed for potential implementation in the Greek cement industry. For CO2 capture, two technologies will be investigated in parallel: carbonate looping, where CO2 is separated via its reaction with a solid sorbent, and the separation of CO2 via selective membranes. The carbonate looping technology is relatively mature and its main disadvantage remains the high cost of solids with high CO2 sorption capacity and stability. In the project, we will aim to develop low-cost CO2 sorbents that exhibit these characteristics, starting from natural minerals after suitable modification. The use of membranes for the separation of CO2 is a more pre-mature technology, but can lead to breakthroughs in the field if successful. The membranes can achieve almost 100% selectivity in continuous operation mode, thereby leading to reduced cost. In the frame of the project, we will develop materials with a suitable porous structure and high ionic and electrical conductivity that will serve as matrix for the production of dual-phase membranes with high permeability and mechanical strength. With regards to CO2 conversion, we propose the novel process of sorption enhanced CO2 hydrogenation to methanol. The novelty of the process lies in the presence of a suitable water sorbent in the reactor, which continuously removes the water produced from the reaction and shifts the equilibrium to the products side, thus eliminating the main bottleneck of the CO2-to-methanol process and allowing high conversions and yields at industrially relevant operating conditions.