Hydrate-based Capture CO2 and Purification CH4 from Simulated Landfill Gas with Synergic Additives Based on Gas Solvent

Abstract

Treatment and subsequent use of Landfill gas (LFG) are garnering huge interest for both energy recovery and mitigation of environmental impact. This work presents the thermodynamic, kinetic and separation efficiency studies of purifying simulated LFG (45.0 mol% CO2/CH4 binary mixture) based on hydrate crystallization approach. Particularly, creative synergic additives (comprise traditional hydrate promoter (tetra-n-butyl ammonium bromide, TBAB and tetrahydrofuran, THF) and gas solvent (dimethyl sulfoxide, DMSO)) were proposed to enhance the separation process. The hydrate crystallization process was conducted at a certain driving pressure with proportional integral derivative (PID) isochoric controller. The residual gas phase and the decomposition gas phase of the hydrate slurry were sampled and analyzed. Based on the above experimental data, the gas storage capacity, unit system gas consumed rate, gas selectivity and separation efficiency were calculated to evaluate the separation process. For the synergic additives with the fixed concentrations studied in this work, it was found that, the synergic additives (TBAB-DMSO) could not only remarkably reduce the equilibrium LFG hydrate formation pressure, but also accelerate the formation rate and improve the gas storage capacity of LFG through promote the solubility of CO2 and further enhance the selectivity of CO2 in the hydrate process. It will be of practical interest in relation to the development of hydrate-based gas separation and of potential importance for the industry application of gas hydrate.