Post combustion carbon capture with supported amine sorbents: From adsorbent characterization to process simulation and optimization

Abstract

Supported amine sorbents are extensively studied in literature due to their moisture tolerating abilities. Most of the work with this group of adsorbents pertain to experimental studies on adsorption capacity, kinetics, and stability tests on powdered sorbents. Only a handful of published studies have carried out thermodynamic assessment and process modelling to evaluate the performance of supported amine sorbents in the context of pressure and temperature swing adsorption processes. In this work, we have evaluated a commercially available mesoporous silica (PERLKAT) adsorbent grafted with N-[3-(trimethoxysilyl)propyl] ethylenediamine for post-combustion carbon capture by vacuum swing adsorption process (VSA). Experiments were first carried out to obtain information on single component and ternary equilibrium data. The adsorbent has a total capacity of 0.95 mmol/g at 0.15 bar CO2 and 0.8 mmol/g at 0.05 bar CO2 respectively at 70 °C. Ternary experiments at low relative humidity shows that the CO2 capacity is not affected in the presence of moisture. These results were used as input to simulate and optimize a 6-step dual reflux vacuum swing adsorption (VSA) cycle. Detailed process optimization shows that it is possible to capture 90% of the CO2 at 95% purity using our adsorbent. The minimum specific energy is 1 MJ/kg CO2 captured on an electric basis when the VSA process is operated at 90 °C.