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Thermodynamics and kinetics of CO2 hydrate formation in the presence of cellulose nanocrystals

University of British Columbia

The kinetics of gas hydrate formation are of interest in various energy and environmental applications of gas hydrates. One such example is the hydrate based gas separation (HBGS) as a possible method to capture CO₂ from either pre-combustion or post-combustion gas mixtures present in integrated gasification combined cycle (IGCC) and conventional power plants respectively. In such applications additives are included to improve the kinetics of gas hydrates. In this work, carbon dioxide hydrate was formed in aqueous suspensions of cellulose nanocrystals (CNC) and the induction time and rate of hydrate crystal growth was compared to data obtained with hydrates formed in pure water (blank). 24 runs were made for each group (blanks and CNCs). A suspension with a CNC concentration 0.75 wt% was employed to determine whether CNC could reduce the induction time and enhance hydrate growth rate as it has been reported for carbon nanotubes and other nanoparticle suspensions. Hydrate formation experiments were carried out in semi-batch mode setup in a high pressure crystallizer with overhead stirring. The temperature and the pressure were 274.15K and 2370 kPa respectively, this pressure is 1000 kPa above the equilibrium pressure of CO₂ hydrates at the mentioned temperature. Statistical analysis was performed with the data gathered to establish whether there is an effect of CNC nanoparticles in hydrate kinetics. The results show that the CNC did not have a statistically significant impact on CO₂ hydrate formation. This study also compared the results with data from the literature about the effect of other nanoparticles on gas hydrate formation.

Text

2021-02-18

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/77336

Chemical and Biological Engineering

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/