Theoretical Investigation of Metal Oraganic Frameworks

Abstract

Metal-Organic Frameworks (MOFs) with coordinatively unsaturated sites (cus's) have shown very good adsorption properties for Sulphur-containing aromatic compounds. One of the promising applications of MOFs currently under investigation is their use in the separation of sulphur-containing compounds from various hydrocarbons. A theoretical investigation of thiophene, dibenzothiophene (DBT) and toluene adsorption on CPO-27(X) and CuBTC MOFs, and NaY zeolite (Si/Al ratio 2.7:1) is presented. The reliability of the method was tested on the small cluster models mimicking the coordinatively unsaturated sites in CPO-27 MOF with respect to the CCSD(T/CBS benchmark calculations. The results of periodic DFT calculations employing vdW-DF2 functional accounting for the dispersion interactions obtained herein were used for the interpretation of experimental results obtained by experimental co-workers. At low coverages, the interaction energies calculated for thiophene adsorbed on CPO- 27(X), where X is Cu, Zn, Mg, Co, and Ni, are increasing in order Zn2+ < Cu2+ < Mg2+ < Co2+ < Ni2+ , which is in good agreement with the experimental data. The adsorption in CPO-27(X) is driven mainly by two factors: (i) an electrostatic interaction between X2+ cus site of CPO- 27(X) and Sulphur atom on thiophene , and (ii)..