Aminosilane-Functionalized Cellulosic Polymer for Increased Carbon Dioxide Sorption

Improvement in the efficiency of CO2 separation from flue gases is a high-priority research area to reduce the total energy cost of carbon capture and sequestration technologies in coal-fired power plants. Efficient CO2 removal from flue gases by adsorption systems requires the design of novel sorbents capable of capturing, concentrating, and recovering CO2 on a cost-effective basis. This paper describes the preparation of an aminosilane-functionalized cellulosic polymer sorbent with enhanced CO2 sorption capacity and promising performance for use in postcombustion carbon capture via rapid temperature-swing adsorption systems. The introduction of aminosilane functionalities onto the backbone of cellulose acetate was achieved by the anhydrous grafting of N-(2-aminoethyl)-3-aminoisobutyldimethylmethoxysilane. The dry sorption capacity of the modified cellulosic polymer reached 27 cc (STP) CO2/cc sorbent (1.01 mmol/g sorbent) at 1 atm and 39 cc (STP) CO2/cc sorbent (1.46 mmol/g sorbent) at 5 atm and 308 K. The amine loading achieved was 5.18 mmol amine (nitrogen)/g sorbent. Exposure to water vapor after the first dry sorption cycle increased the dry sorption capacity of the sorbent by 12% at 1 atm, suggesting its potential for rapid cydic adsorption processes under humid feed conditions. The CO2 sorbent was characterized in terms of chemical composition, density changes, molecular structure, thermal stability, and surface morphology.