Thermodynamic properties of CO2 + SO2 + CH4 mixtures over wide ranges of temperature and pressure. Evaluation of CO2/SO2 co-capture in presence of CH4 for CCS

Abstract

In this work, density, vapor-liquid equilibrium and speed of sound measurements of the mixtures [CO2 + 4.72 mol% SO2 + 1.85 mol% CH4] and [CO2 + 0.09 mol% SO2 + 1.54 mol% CH4] were performed over the temperature range 263–373 K and at pressures of up to 30 MPa for density and up to 190 MPa for speed of sound. For the speed of sound measurements, the mixtures were doped with ≅0.8 mol% CH3OH. We compared our results to the values calculated using an extended version of the equation of state for combustion gases (EOS-CG) that includes binary models for the CO2 + SO2 and CO2 + CH4 subsystems, and a perturbed-chain statistical associating fluid theory (PC-SAFT) equation of state, validating both equations in this way. From our experimental results, we evaluated the impact of the simultaneous presence of SO2 and CH4 as impurities in anthropogenic CO2 on selected parameters for carbon capture and storage technology. With the understanding that chemical effects have not been considered, we concluded that the presence of 4.72 mol% SO2 compensates for the negative effect of 1.85 mol% CH4 on most of the studied parameters, resulting in a favorable fluid for carbon, capture and storage, contrary to the mixture with 0.09 mol% SO2 and 1.54 mol% CH4.