Accelerative Effect of l-Tryptophan Combined with Graphene Oxide on the Kinetics of CO2 Hydrate Formation

The carbon capture and storage technology based on the hydrate method can effectively capture CO2 gas and reduce greenhouse gas emissions; however, the slow and random formation of hydrate has greatly hindered the commercial application of this technology. The effect of l-tryptophan (l-trp) on the kinetics of CO2 hydrate formation with graphene oxide (GO) was investigated. The results showed that the combination of l-trp and GO could effectively accelerate the hydrate formation rate, increase the gas consumption, and promote the formation of the CO2 hydrate. Compared with pure water, the optimal concentration of 0.200 wt % l-trp and 0.020 wt % GO can increase the cumulative gas consumption by 16.229%, shorten the induction time by 69.300%, and shorten the time of 90% hydrate formation by 54.895%. Kinetic experiments and morphological observations show that a low dose of GO could promote heat and mass transfer in the process of CO2 hydrate formation, but with the increase of concentration, GO particles will agglomerate, and the probability of hydrate nucleation will be greatly reduced. The strong wall-climbing effect of l-trp could promote hydrate growth against the reactor wall and gas–liquid exchange. This work provides an experimental basis for the commercialization of the hydrate technology.