Ke Bei,Junliang Wang,Shuyan Zhou,Guangna Xie,Yanmei Xu,Liang Wang,Zhuoran Jiang,I-Ming Chou,Zhiyan Pan
Accurate expansion data for CO 2 in petroleum model compounds (e.g., alkanes, cycloalkanes and aromatics) are fundamental information for CO 2 sequestration and enhanced oil recovery in oil reservoir. In this study, the volume expansion of the CO 2 + octane mixture was measured using a fused silica capillary cell with in situ Raman spectroscopy. A section of water was loaded between octane and CO 2 in the fused capillary tube to seal the octane whilst allowing the diffusion of CO 2 into the octane. Raman spectroscopy was applied during our experiments to verify that the CO 2 + octane mixture reached phase equilibrium. Moreover, a good quadratic relationship was observed between the Raman peak intensity ratio and volume expansion factor. It was verified that this method can be used not only just to obtain more accurate experimental data, but also to protract additional volume expansion factor curves or curved surfaces from measured Raman peak intensity ratio using this equation. Over an extended temperature and pressure range, this method was thus shown to be more efficient and accurate than the traditional pressure–volume–temperature methods.
Wenwen Luan,Chunyu Wang,Zuoxiang Zeng,Weilan Xue,Fei Liang,Yu Bai
In this work, the samples of polyvinyl butyral (PVB) with an average degree of acetalization of 79.56% and the average molecular weight of 68.696 kg·mol −1 were prepared by polyvinyl alcohol (PVA) and n-butyraldehyde, catalyzed by p-Toluenesulfonic acid (PTSA). The intrinsic viscosities of PVB were measured in ethanol/water solutions in the temperature range of 293.15–313.15 K. The expansion factors of PVB molecular chains were calculated with the intrinsic viscosity data. The related thermodynamic parameters were derived from the temperature dependence of expansion factors and results indicate that the quality of mixed ethanol/water solvents for PVB solutions decreases with the increase of temperature and the volume fractions of water.
Junliang Wang,Shuyan Zhou,Ke Bei,Dan Zhang,I-Ming Chou,Zuhua Chen,Chunmian Lin,Zhiyan Pan
To investigate the volume expansion of a carbon dioxide (CO2) + n-hexane mixture at different temperatures and pressures, we developed a measurement setup using an optically transparent fused silica capillary cell (FSCC) combined with Raman spectra. The results showed that the method is feasible, the water seal is effective in its ability to avoid vaporization of n-hexane, and Raman spectra can help ensure the system equilibrium. The volume expansion factor of the CO2 + n-hexane mixture increased with increasing pressure from 1 to 10 MPa and decreased with increasing temperature from 30 to 80 °C. It was found that the trend of the expansion factor of the CO2 + n-hexane mixture was steeper at a higher temperature. When the temperature was 30 °C, the volume expansion factor increased from 2.15 to 13.61 as the pressure increased from 5.0 to 6.5 MPa. Meanwhile, the volume expansion factor increased from 2.36 to 19.40 as the pressure increased from 8.0 to 9.2 MPa at 60 °C. In addition, we obtained a significant and positive relationship between the volume expansion factor and the Raman peak height ratio of CO2 and n-hexane using a quadratic equation.
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