Selective capture of CO2 over N2 and CH4: B clusters and their size effects

TL;DR

This study uses density-functional theory to explore how planar boron clusters of different sizes selectively adsorb CO2 over N2 and CH4, revealing size-dependent selectivity trends that could inform carbon capture technologies.

Contribution

It provides a comparative analysis of CO2, N2, and CH4 adsorption on B8, B12, and larger boron clusters, highlighting size effects on selectivity for CO2 capture.

Findings

CO2 can be selectively adsorbed over N2 on B12 clusters at room temperature.

Selective adsorption of CO2 over CH4 is possible on both B8 and B12 clusters.

Selectivity trends extend to larger boron clusters, including B10-13 and B36.

Abstract

Using density-functional theory (DFT), we investigate the selectivity of adsorption of CO2 over N2 and CH4 on planar-type B clusters, based on our previous finding of strong chemisorption of CO2 on the B10-13 planar and quasiplanar clusters. We consider the prototype B8 and B12 planar-type clusters and perform a comparative study of the adsorption of the three molecules on these clusters. We find that, at room temperature, CO2 can be separated from N2 by selective binding to the B12 cluster and not to the B8 cluster. Selective adsorption of CO2 over CH4 at room temperature is possible for both clusters. Based on our DFT-adsorption data (including also a semi-infinite Boron sheet) and the available literature-adsorption value for N2 on the planar-type B36 cluster, we discuss the selectivity trend of CO2 adsorption over N2 and CH4 with planar-cluster size, showing that it extends over sizes including B10-13 clusters and significantly larger.