Carbon capture and storage technologies are projected to increasingly contribute to cleaner energy transitions by significantly reducing CO2 emissions from fossil fuel-driven power and industrial plants. The industry standard technology for CO2 capture is chemical absorption with aqueous alkanolamines, which are often being mixed with an activator, piperazine, to increase the overall CO2 absorption rate. Inefficiency of the process due to the parasitic energy required for thermal regeneration of the solvent drives the search for new tertiary amines with better kinetics. Improving the efficiency of experimental screening using computational tools is challenging due to the complex nature of chemical absorption. We have developed a novel computational approach that combines kinetic experiments, molecular simulations and machine learning for the in silico screening of hundreds of prospective candidates and identify a class of tertiary amines that absorbs CO2 faster than a typical commercial solvent when mixed with piperazine, which was confirmed experimentally.

No abstract

The contribution of CO2 present in natural gas to the total GHG emissions of the gas plant can be significant (up to 20% for Middle East Gas). When both H2S and CO2 are present, the CO2 capture cost is currently very high. The method developed to tackle this challenge is an innovative architecture of the acid gas treatment chain based on a new ultra-selective absorption process. The redesigned acid gas treatment architecture is detailed and compared with available technologies on the market. The technical cost of avoided CO2 can be reduced by up to 70% by using the new ultra-selective process compared to the available CO2 capture technology. This new acid gas treatment architecture can reduce by up to 20% the energy consumption to capture CO2. A new ultra-selective solvent has been developed using computational screening tools combined with experiments measuring physical, operational, thermodynamic, and kinetic properties. Those serve as input of a process simulation tool validated with medium-pressure absorber and regenerator pilot plant data. The new solvent is currently at TRL4 validation, a selectivity of more than 75% (CO2 slippage) has been observed on the pilot plant, with a H2S specification in the treated gas kept around 5 ppm. This result is the consequence of both a new solvent formulation (selective amine) and optimal operating conditions. There is, moreover, no increase in regeneration duty for the new solvent.

Removing CO2 from natural gas or biogas in the presence of H2S is technically challenging and expensive as it often requires separation of both acid gases from the gas, typically using an aqueous amine solution, followed by separation of CO2 from H2S and conversion of H2S into solid S. In this work, the proof of concept of electrochemical, instead of thermal, regeneration of an aqueous amine solution is developed. This invention might be a very promising technology and has several advantages. It has H2S versus CO2 selectivity of 100%, can directly convert H2S into S and H2, and is economically competitive with CO2 desorption energy around 100 kJmol−1 and H2S conversion around 200 kJmol−1. If renewable energy is used for electrochemical regeneration, CO2 emissions due to the CO2 capture process can be significantly reduced.

No abstract