Sequestration of carbon dioxide in coal: Energetics and bonding from first-principles calculations

Abstract

Sequestration of CO2 in unmineable coalbeds is one of the attractive ways being investigated to reduce the CO2 concentration in the atmosphere. Extensive experimental studies have demonstrated that storage of CO2 molecules in coal seam involves both chemisorption and physisorption, but the underlying mechanism at the atomic scale has remained elusive. We report results of first-principles density-functional-theory calculations for the interaction between molecular CO2 and coal. The calculations show that chemisorption of CO2 in defective coal is possible, and CO2 can form chemical bonding with defective coal, particularly at the defects involving carbon and hydrogen vacancies and epoxy functional groups. On the other hand, formation of chemical bonding of CO2 with defect-free coal network is unlikely.