Efficient Theoretical Screening of Solid Sorbents for CO&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt; Capture Applications

Yuhua Duan,Henry Henry Pennline,David Luebke

doi:10.4236/ijcce.2012.11001

Abstract

By combining thermodynamic database mining with first principles density functional theory and phonon lattice dynamics calculations, a theoretical screening methodology to identify the most promising CO2 sorbent candidates from the vast array of possible solid materials has been proposed and validated. The ab initio thermodynamic technique has the advantage of allowing identification of thermodynamic properties of CO2 capture reactions without any experimental input beyond crystallographic structural information of the solid phases involved. For a given solid, the first step is to attempt to extract thermodynamic properties from thermodynamic databases and the available literatures. If the thermodynamic properties of the compound of interest are unknown, an ab initio thermodynamic approach is used to calculate them. These properties expressed conveniently as chemical potentials and heat of reactions, which obtained either from databases or from calculations, are further used for computing the thermodynamic reaction equilibrium properties of the CO2 absorption/desorption cycles. Only those solid materials for which lower capture energy costs are predicted at the desired process conditions are selected as CO2 sorbent candidates and are further considered for ex- perimental validations. Solid sorbents containing alkali and alkaline earth metals have been reported in several previous studies to be good candidates for CO2 sorbent applications due to their high CO2 absorption capacity at moderate work- ing temperatures. In addition to introducing our computational screening procedure, in this presentation we will sum- marize our results for solid systems composed by alkali and alkaline earth metal oxides, hydroxides, and carbonates/bicarbonates to validate our methodology. Additionally, applications of our computational method to mixed solid systems of Li2O with SiO2/ZrO2 with different mixing ratios, our preliminary results showed that increasing the Li2O/SiO2 ratio in lithium silicates increases their corresponding turnover temperatures for CO2 capture reactions. Overall these theoretical predictions are found to be in good agreement with available experimental findings.

Highlights

Carbon dioxide is one of the major combustion products which once released into the air can contribute to the global climate warming effects [1,2,3]
The thermodynamic data for these oxides, hydroxides and corresponding carbonates and bicarbonates are available in thermodynamic databases, in order to validate our theoretical approach, we made the ab initio thermodynamic calculations for these known crystals
By combining thermodynamic database searching with first principles density functional theory and phonon lattice dynamics calculations, from vast of solid materials, we proposed a theoretical screening methodology to identify most promising candidates for CO2 sorbents

Summary

Introduction

Carbon dioxide is one of the major combustion products which once released into the air can contribute to the global climate warming effects [1,2,3]. In order to mitigate the global climate change, we must stop emitting CO2 into the atmosphere by separating and capturing CO2 from coal combustion and gasification plants and sequestering the CO2 underground. Current technologies for capturing CO2 including solvent-based (amines) and CaO-based materials are still too energy intensive. There is critical need for new materials that can capture and release CO2 reversibly with acceptable energy costs. Solid sorbent materials have been proposed for capturing CO2 through a reversible chemical transformation and most of them result in the formation of carbonate products. Solid sorbents containing alkali and alkaline earth metals have been reported in several previous studies to be good candidates for CO2 sorbent applications due to their high CO2 absorption capacity at moderate working temperatures [4,5,6]

Methods

Results

Conclusion