Effect of Cyclooctane and L-Tryptophan on Hydrate Formation from an Equimolar CO2-CH4 Gas Mixture Employing a Horizontal-Tray Packed Bed Reactor

A fundamental study on hydrate formation from an equimolar CO2-CH4 gas mixture has been carried out with two focal points: accelerating the kinetics of hydrate formation and enhancing the gas separation efficiency of the process. To this effect, the impact of inducing different hydrate structures from the same gas mixture by introducing suitable additives into the system has been investigated, and experiments are being carried out in a horizontal packed bed reactor at two different initial pressures, 3.5 and 5.0 MPa, to study the effect of driving forces on the kinetics of hydrate formation and the separation efficiency of the process. sH hydrate former cyclooctane (Cyclo-O) induces rapid nucleation of hydrate and also yields significant gas uptake in hydrates, 29.55% higher compared to the water system. This may be attributed to the simultaneous formation of sH and sI hydrates when Cyclo-O is present in the system. It was observed that the environmentally benign hydrophobic amino acid tryptophan in low concentration (1 wt %) can effectively accelerate the kinetics of hydrate formation, with 90% water to hydrate conversion being obtained within the first 30 min of hydrate formation. Further, the use of Cyclo-O and tryptophan together shows a synergistic effect, resulting in the highest gas uptake among all the systems studied. Although the problem of slow kinetics of hydrate formation from CO2-CH4 gas mixtures has been satisfactorily solved through this work, there are still significant strides that need to be made toward improving the separation efficiency of the process. The formation of the mixed hydrate is unable to return a satisfactorily high efficiency for gas separation.