Reliable speed of sound, c, values in CO 2 -rich mixtures and pure CO 2 are required for carbon capture and storage (CCS) technology but are difficult to determine, particularly at relatively high frequencies. We tested the suitability of methanol as doping agent to obtain accurate c values in CCS systems at 5 MHz. We measured c in seven CO 2 -rich, CO 2 +methanol mixtures between 263.15 and 323.15 K and up to 196.30 MPa, and we extrapolated the values to obtain c in pure CO 2 .Additionally, we measured c from 263.15 to 373.19 K and up to 190.10 MPa in two CO 2 -rich, CO 2 +SO 2 mixtures with the same SO 2 composition, which is of interest for CCS, with one mixture doped with methanol. We compared our results for pure CO 2 with the literature and the Span and Wagner equation of state (EoS). We validated the PC-SAFT EoS and the modeling with the REFPROP 9 software for the mixtures by comparing the predicted values with our experimental data under the studied conditions. We conclude that methanol is a suitable doping agent to measure c in pure CO 2 and CO 2 -rich mixtures. For the CO 2 +SO 2 mixtures, the effect of methanol on the experimental values is small and negligible for modeling. *Manuscript Click here to download Manuscript: Revised Manuscript.docx Click here to view linked References

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CO2 capture and storage (CCS) is an important technology for avoiding atmospheric CO2 emissions, which are principally originated from fossil fuels combustion.Anthropogenic CO2 contains impurities that can strongly modify the properties of the stream.Several authors have showed that some of these impurities, such as SO2 present in emissions from sulfur containing fuels, could be favorable for some steps of the process, and the possibility of co-capture has been proposed. To assess this possibility with regard to the transport stage of CCS, we determined the influence of SO2 on selected parameters of transport by pipeline (minimal operational pressure, pressure and density drops, distance between boosters, booster power, and inner diameter of the pipeline and the Joule-Thomson coefficient). For this purpose, we obtained new and accurate experimental data for the density and vapor-liquid equilibrium of five CO2+SO2 mixtures under conditions of interest for CCS and speed of sound data for four of them. We compared our results with those found in the literature and with the values calculated using two equations of state for their validation: PC-SAFT and an extended version of EOS-CG that includes a binary model for the CO2+SO2 mixture. Allowing for the fact that chemical effects due to the presence of SO2, such as pipeline corrosion, have not been considered, we conclude that CO2/SO2 co-capture might favor and decrease the costs of the transport step of this technology, helping to avoid emissions of a highly toxic gas to the atmosphere without high desulfuration expenses.

Vapor pressures of (1-butanol þ 1,8-cineol) at 10 temperatures between (278.15 and 323.15) K were measured by a static method. The reduction of the vapor pressures for obtaining activity coefficients and excess molar Gibbs energies was carried out by fitting the vapor pressure data to the Wilson equation according with Barker's method. Four equations of state (EOS) were used to correlate the vapor-liquid equilibrium (VLE) and for describing the volumetric behavior of the mixture. Two of them are modifications of the temperature-dependent function R(T r ) in the attractive term of Peng-Robinson equation as proposed by Mathias (PRM) and by Stryjek-Vera (PRSV). In both cases a volume translation (VT) according to Peneloux was considered. The other two models applied are based on the theory of perturbations: statistical associating fluid theory (SAFT) and perturbed-chain statistical associating fluid theory (PC-SAFT). The best description of the phase equilibrium was achieved by the Stryjek-Vera modification, whereas SAFT and PC-SAFT provided the best volumetric results.

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