Design of novel conjugated microporous polymers for efficient adsorptive desulfurization of small aromatic sulfur molecules

Abstract

This paper presents a computational study of the adsorptive desulfurization of small aromatic sulfur compounds by conjugated microporous polymers (CMPs). The density-functional tight-binding method augmented with an R^-6 dispersion correction is employed to investigate the physisorption binding mechanism and electronic properties of the CMP-aromatic sulfur complexes. We show that the widely extended π conjugation in the CMP skeletons is favorable for the non-covalent adsorption of aromatic thiophene and dibenzothiophene via π-π, H-π, and S-π interactions. The average binding energies are calculated to be -6.2 ∼ -15.2 kcal/mol for CMP- thiophene/dibenzothiophene systems. For the dibenzothiophene molecule with larger size and more extended conjugation, it binds more than twice stronger to CMP than the thiophene molecule. We show that the replacement of quinoline unit to the phenylene group in the network linker effectively enhances the average binding capacities by around 0.8-1.8 kcal/mol. Our calculations theoretically demonstrate that CMPs materials are kind of promising candidates for the adsorptive desulfurization of small aromatic sulfur compounds. This paper provides useful theoretical guidance for design of novel carbon-based adsorbents for adsorptive desulfurization.

Keywords: Adsorptive desulfurization; Aromatic sulfur compounds; Conjugated microporous polymers; Density-functional tight-binding calculations.