Hydrate-Based Multistage Biogas Separation Using a Novel Jet Impingement Stream Reactor

Hydrate-based separation and capture technology, as a green and economical gas separation technology, can be used to purify biogas by removing CO2 to increase the calorific value and energy density. To achieve pilot-scale biogas separation, a 15 L pilot-scale reactor with novel jet impingement stream was designed for fast and efficient CH4 recovery and CO2 capture and pure CH4 was obtained by multistage separation in this work. Hydrate nucleation and growth were enhanced by jet impingement stream in aqueous solution with 5.0 wt % tetrabutylammonium bromide. The space velocity of the reactor reached a maximum value of 557 h–1; the gas uptake reached up to 1.00 mol/L at 4.0 MPa; and the fastest time to reach 80% of the rate of gas uptake was about 2.5 min at 3.0 MPa and 277 K. The effects of the pressure and temperature driving force on the CH4 concentration in residual gas, CH4 recovery rate, CO2 capture ratio, and gas hydration rate were studied. By a four-stage hydrate-based gas separation process, the CH4 concentration could be increased from 50.0 to about 95.1%. This work provides insights for the industrial application of continuous hydrate-based biogas separation.