Experimental study on hydrate-based CO2 removal from CH4/CO2 mixture

In this work, hydrate-based CO2 removal from a CH4/CO2 mixture was studied. CH4/CO2 led to faster hydrate formation than pure CH4, because the existence of CO2 resulted in easier hydrate nucleation. Kinetic separation of CO2 was observed in the CH4/CO2 hydrate formation with different initial CO2 proportions (1.83–27.76%) due to the higher CO2 affinity of formation of hydrates. However, the initial CO2 proportion of CH4/CO2 showed no obvious effects on the hydration ratio of CH4 and CO2 and the separation efficiency when the gas was superfluous in hydrate formation. In addition, hydrate-based multistage separation of CH4/CO2 was established and conducted at different initial pressures (4, 5 and 6 MPa). The CH4 proportions were increased from 72.24% to 97.30%, 97.22% and 97.14% after separation by four, five and seven stages at initial pressures of 4, 5, and 6 MPa, respectively.