DFT calculations for adsorption of carbonyl sulfide gas on pristine and Al-doped B۳۲N۳۲ nanotubes

COS (carbonyl sulfide) is a naturally occurring gas or a by-product of chemical processing, oil recovery, and coal combustion. COS is a sulfur-containing compound and can cause damage to equipment and pipelines in oil and gas refineries. In addition, COS can convert to sulfuric acid in the presence of water, which can lead to corrosion and other problems. Therefore, its elimination is important in the gas industry. One of the conventional industrial methods for removing this destructive gas is its hydrolysis in the presence of expensive catalysts. Hydrolysis of COS to decompose it into carbon dioxide (CO۲) and hydrogen sulfide (H۲S) requires control of reaction conditions, including temperature, pressure, and gas flow rate, to optimize reaction efficiency and selectivity. In this study, we are trying to investigate the possibility of removing carbonyl sulfide by boron nitride nanotubes (BNNTs) in the gas phase using density functional theory (DFT). Different adsorption modes of COS molecule on the pristine and Al-doped BNNTs were studied using the dispersion-corrected DFT calculations. All the calculations were carried out with the Gaussian ۰۹ program at the B۳PW۹۱/۶-۳۱۱G(d,p) level of theory. Concerning the dispersion correction, to achieve more accurate findings, the wB۹۷XD functional was used as a version of Grimme’s D۲ dispersion model. Unlike the pristine nanotube, the electronic properties of aluminium-doped BNNTs were very sensitive to the carbonyl sulfide adsorption. Also, it is found that the interaction between the aluminium atom and its neighboring N atoms in the aluminium-doped BNNTs is very strong, which would hinder the dispersion and clustering of the Al atoms over the BNNTs surface. The adsorption energies of COS molecules over the Al-doped BNNTs were in the range of −۰.۳۵ to −۰.۸۸ eV, which indicates the quite strong interaction of this molecule with the surface of boron nitride nanotube. The obtained results indicated that carbonyl sulfide can be adsorbed on the surface of Al-doped BNNTs through its nitrogen lone pair electrons with the acceptable adsorption energy. It is proposed that boron nitride nanotubes be used instead of conventional catalyst-based industrial methods.

کلیدواژه ها:

Adsorption ، Density functional theory ، Carbonyl sulphide ، Boron nitride nanotube ، Al-doped