High Selectivity CO2 Capture from Biogas by Hydration Separation Based on the Kinetic Difference in the Presence of 1,1-Dichloro-1-fluoroethane

摘要

The separation of a gas mixture by hydrate technology is considered one of the most promising new separation technologies. Previous studies on biogas purified by hydrate separation had high energy consumption because of low separation efficiency. In this paper, we used 1,1-dichloro-1-fluoroethane (HCFC-141b) as an additive to capture CO2 from a mixture gas of 67.00 mol % CH4 and 33.00 mol % CO2, which not only reduced the hydrate formation pressure but also enhanced the difference of methane and carbon dioxide hydrate formation kinetics. The influence of HCFC-141b concentration, feed gas pressure, and initial gas/liquid volume ratio on separation efficiency and the kinetics of hydrate formation were investigated. The results showed that the CO2 captured ratio was 97.03% at 284.1 K @2MP and the separation factor was 61.38. The largest CO2 captured ratio was 97.89%. The concentration of CH4 in the residual gas phase increased from 67.00 to 98.01 mol %. The maximum gas hourly space velocity of the reactor reached 14.45 h(-1), and the hydrate formation rate constant was 2.15 x 10(-4) (mol(2)/(s.J)). Furthermore, the energy consumption was calculated by Aspen HYSYS software. The energy consumption of CH4 obtained from biogas at 284.1 K @2MP is 0.3530 kWh/kgCH(4). HCFC-141b acts as a kinetic and thermal promoter, which improved the energy efficiency of hydrate separation and reduced the energy consumption.

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