Kinetic characterization of gas mixture separation by hydrate method with 1,3-dioxolane and multi-walled carbon nanotubes complex synergistic system

Abstract

In the transition to cleaner energy sources, low-carbon energy gases are expected to dominate fuel consumption. Hydrate-based gas separation technology is poised to play a key role in the decarbonization pathway for energy gases with high CO2 content. However, the current hydrate gas separation method faces challenges, including a long induction period, slow growth rate, and low separation efficiency. In light of these challenges, this paper investigates the kinetics of CH4/CO2 gas mixture hydrate formation and its separation efficiency in 1,3-dioxolane (DIOX) and multi-walled carbon nanotubes (MWCNTs). The experimental results showed that both DIOX and MWCNTs, when used in low concentrations, had a certain thermodynamic promotion effect, with DIOX showing a superior performance. DIOX outperforms MWCNTs in terms of gas consumption and induction time. whereas MWCNTs was superior to DIOX in terms of growth rate, and the purification rate at the same concentration could be increased by 32.66 %∼234.43 % compared with the DIOX system. Subsequently, this paper further investigated the effect of 300 ppm DIOX complexed with different concentrations of MWCNTs on hydrate formation and separation efficiency. DIOX was found to occupy the main promotional role in this complex system, retaining the growth acceleration stage in the DIOX system. When compounded with 200 ppm MWCNTs, the T90 time was shortened by 28.78 %∼59.29 %, and the purification rate could be increased by 86.4 % compared with a single 300 ppm DIOX system. This work provides guidance on the use and compounding of thermodynamic and kinetic promoters and aids hydrate technology where faster hydrate growth rates and more efficient gas mixture separation are required.