Investigation of Tetra-<i>n</i>-Butyl Ammonium Bromide Semiclathrate Hydrate-Based CO<sub>2</sub> Capture by Kinetic and In Situ Raman Spectroscopy Measurement
Xi‐Yue Li, Jin Yan, Dong‐Liang Zhong, Shijian Lu, Bin‐Bin Ge
Abstract
In this work, the formation of tetra- n -butyl ammonium bromide (TBAB) semiclathrate hydrate for CO 2 capture was studied by conducting experiments in a kinetic setup coupled with high-pressure in situ Raman spectroscopy. The impacts of TBAB concentration and operating temperature on CO 2 incorporation into TBAB semiclathrate hydrates were investigated from the macroscopic and microscopic perspectives. It was found that the structure transition of TBAB semiclathrates from type A to type B occurred in the presence of CO 2 and could be identified by the splitting of the Raman peak at 1447 and 1465 cm –1 (C–C stretching vibration mode in TBA + ). CO 2 consumption increased substantially upon the occurrence of hydrate structure transition, indicating that a larger amount of CO 2 is incorporated into the TBAB semiclathrate of type B. The structure transition of the TBAB semiclathrate occurring at 2.57 mol % TBAB is faster than that at 0.29 and 3.72 mol % TBAB, and CO 2 consumption obtained at 2.57 mol % TBAB is greater. When the temperature is reduced from 282.15 to 279.15 K, the structure transition of the TBAB semiclathrate occurs faster, but the amount of CO 2 trapped in the hydrate is reduced. Therefore, the TBAB semiclathrate formed at 2.57 mol % TBAB and 282.15 K is a suitable system for CO 2 capture using TBAB semiclathrate hydrates.