Basic Solubility Measurements for the Design of an Integrated Biogas Purification Process

Abstract

Basic solubility measurements have been carried out in order to investigate the co-solubility of carbon dioxide (CO₂) and methane (CH₄) in water at 298.15 K. Since there is no publicly available solubility data for moderate pressures (as applied in pressurized water scrubbing) for the removal of carbon dioxide from biogas, mixed gas solubilities subject to pressures of approximately 0.2 MPa to 1.5 MPa were investigated using a self-designed equilibrium cell. Since CO₂ and particularly methane are only sparsely soluble in water, a precise method had to be developed for measuring the dissolved amount of both solutes at various pressures. Additionally, reference measurements with pure solutes were completed and compared to existing literature data for the respective solutes to validate the method of measurement. The results show a good agreement with the literature data. An influence of the dissolved CO₂ on the solution behaviour of methane was found. The solution equilibrium is analysed by fitting the data to the Krichevsky-Kasarnovsky-Equation of Henry’s Law.