Evaluation of Structural and Thermodynamic Parameters of Dibenzothiophene Desulfurization by Carbon Nano-Filter

Abstract

In crude oil and oil cuttings, there are some sulfurous, nitrogenous, oxygenated compounds, metals, and unsaturated compounds. They can have destructive effects on equipment, catalysts, and the quality of final products. Due to the importance of the problem, one of the most important operations in any refinery is the purification operation, the purpose of which is to eliminate or reduce such harmful compounds, especially sulfur compounds. The most common industrial method for its removal is hydrogen desulfurization (hydrodesulfurization). Of course, this method also has disadvantages and it is necessary to use catalysts that, in addition to sulfur removal, improve other fuel properties. This study investigated the approach mechanism of dibenzothiophene (DBT) to chemically active sites of carbon nanotubes and dehydrogenates them. After simulating and optimizing the structure of dibenzothiophene and carbon nanotube (8–8) has been calculated and evaluated the structural, electrical, and thermodynamic properties of the dehydrogenation reaction by the Density Functional Theory (DFT) method. Carbon nanotube as a nano-catalyst has a different location to interact with dibenzothiophene examined all locations (passing from the central axis). The results show dibenzothiophene is more likely to approach and interact and desulfurize on the end of the carbon nanotube and release H2S gas. In the step of electron exchange, the gap energy reaches (Eg = 5.08 eV) at the end of the nanotube, and is compared to the gap energy on the outer wall of the nanotube (Eg = 5.55 eV). Therefore, different locations of carbon nanotubes are effective in absorbing and converting sulfur compounds.