The Importance of Transport Processes in Silica-Supported, Polyethyleneimine-Impregnated CO2 Sorbents

THe U.S. Department of Energy's Carbon Capture Simulation Initiative (CCSI) is a DOE-wide project focused on the accelerated upscaling of new carbon capture technologies through science-based simulation.  Polyethyleneimine (PEI)-based sorbent processes are one of the primary focuses of the project.  Experimental evidence indicates that CO₂  transport through the bulk of the amine polymer is a significant limiting factor in the capacity of these sorbents.  A microstructurally sensitive model for the uptake of CO₂ in mesoporous silica-supported PEI sorbents has been implemented.  The model includes a two-step reaction mechanism for the adsoprtion of CO₂ in dry conditions, along with transport in the mesopores and in the bulk of PEI.  This talk will present the results of a parametric study that demonstrates the importance of the stability of diffusive intermediates – with the zwitterions as a prime candidate – in the sorbent capacity.  Statistically sensitive comparisons with experimental data will also be made.