posted on 2020-12-24, 20:38authored byHimanshu Khandelwal, M. Fahed Qureshi, Junjie Zheng, Pradeep Venkataraman, Timothy A. Barckholtz, Ashish B. Mhadeshwar, Praveen Linga
Carbon
dioxide capture and storage (CCS)
can play a vital role in overcoming global warming challenges and
can help to reduce carbon footprint significantly from the environment.
Carbon dioxide (CO2) hydrates are a potential option for
CCS, but slow hydrate formation is a technical challenge that needs
to be overcome. Kinetic promoters are often added to improve the formation
rate of gas hydrates and process efficiency. In this systematic and
comprehensive work, the performance of l-tryptophan, an environmentally
friendly promoter, as a kinetic promoter for CO2 hydrate
formation was evaluated using a stirred tank reactor. The kinetic
performance of the CO2 hydrate formation process was evaluated
using varying l-tryptophan concentrations (0, 100, 300, and
1000 ppm) under different experimental pressure and temperature conditions.
The impact of l-tryptophan was assessed using gas uptake
measurements (induction time, hydrate growth rate, and yield) coupled
with visual observations through the front and top view of the reactor.
With the addition of only 300 ppm l-tryptophan, an average
gas uptake of 114 v/v (78% water conversion to hydrates) was achieved
at 273.65 K and 3.4 MPa, which was four times that for the case without
the promoter. Further increase in l-tryptophan concentration
did not result in significant additional improvement. Compared to
277.65 K, experiments conducted at 273.65 and 275.65 K showed much
shorter induction times and better gas uptake performance. With such
an excellent enhancement effect at a low dosage and being environmentally
friendly, l-tryptophan is recommended as a potential kinetic
promoter for CO2 hydrate formation that could be applied
for CO2 capture and storage via gas hydrate technology.