Two-Stage Membrane System for Post-combustion CO2 Capture Application

This work evaluates the viability of a two-stage process using combined nitrogen (N2)-selective and carbon dioxide (CO2)-selective membranes for post-combustion CO2 capture. A novel type of cellulose acetate (CA) hybrid membrane is used here as a N2-selective membrane. The silica functionalized with p-tetranitrocalix[4]arene (Si–CL) was incorporated into the CA matrix, thereby resulting in a CA/Si–CL hybrid membrane. Moreover, the published permeation data of a CO2-selective fixed-site-carrier (FSC) membrane, i.e., polyvinylamine (PVAm) casted on porous polysulfone (PSf), is used here in a simulation study to serve as a second stage membrane. Although experimental work on the CA/Si–CL hybrid membrane is in progress based on the assumptions of initial appreciable results, a two-stage membrane process is proposed in which a N2-selective membrane is placed in the first stage, while a CO2-selective membrane is placed in the second stage. Subsequently, the techno-economic analysis of a two-stage membrane process has been carried out to evaluate the energy demand and CO2 capture cost for post-combustion CO2 capture application. The feasibility analysis shows a slower value of energy consumption (1.0 MJ/kg of CO2) and CO2 capture cost ($20.5/ton of CO2) by employing N2-selective and CO2-selective membranes.