Tetraalkylammonium halide promoted CO2 and CH4 semiclathrate hydrate: Quality of phase equilibrium modeling with various cubic equation of state

Abstract

Tetra-n-butylammonium bromide (TBAB) and tetra-n-butylammonium fluoride (TBAF)-based semiclathrate hydrates present promising solutions for gas sequestration, transportation, and gas storage applications. In this study, the modeling investigations have been conducted on CO₂ and CH₄ semiclathrate hydrates formed with TBAB and TBAF using the Chen-Guo model. To assess the gas phase fugacity, three different equations of state (EoS) are employed. Initially, a comprehensive comparison of these EoS at a concentration of 5 wt% has been conducted. The EoS exhibiting the lowest absolute average relative deviation (AARD%) has been selected, serving as the basis for further comparisons at varying concentrations. Subsequently, the comparisons to different semiclathrate systems are being extended, considering the most efficient EoS and concentration parameters. The simplicity of the vdW-EoS, with its reliance on only two parameters, contributes to its superior performance in the majority of the configurations examined compared to the more complex RK and PR EoS models. These findings contribute to an enhanced understanding of semiclathrate hydrate systems and improve predictive capabilities in this field.