Experimental Study and Statistical Analysis of Ethane Molecular Diffusion Coefficient in N-Methyl-2-Pyrrolidone (NMP) Solvent Using Pressure Decay Method

Among the compounds widely used in the petrochemical industry, we can name olefins and paraffins, which are used according to their carbon content. Separation of ethane from ethylene as an important industrial product for obtaining pure ethylene is of great importance in industry. In this study, calculation and Experimental Research of molecular diffusion coefficient of ethane gas in normal methyl pyrrolidone (NMP) solvent was performed using pressure decay data in a specified time of 12 hours and Sheikhaʹs graphical method. Using the obtained molecular diffusion coefficients, the effect of temperature and pressure on the system was investigated. Also, to confirm the findings, Wilk-Chang relationship, Diaz and statistical analysis were used. According to the observations and diagrams, it can be concluded that with increasing temperature and pressure, the molecular diffusion coefficient of ethane gas in NMP solvent increases. It was also observed that the molecular diffusion coefficient of ethane gas at low pressures did not change much with increasing temperature, but with increasing pressure, increasing temperature shows its effect on the molecular diffusion coefficient. The molecular diffusion coefficients calculated by the Wilk-Chang equation do not have an acceptable overlap with the Sheikha equation, while in the Diaz experimental equation the molecular diffusion coefficients show a very good overlap with the Sheikha equation. The results of statistical analysis showed that although with increasing temperature and pressure, the molecular diffusion coefficient of ethane gas in the solvent increases, but the effect of increasing pressure on the gas diffusion in the solvent is greater than the effect of temperature. The effect of temperature and pressure interaction on the molecular diffusion coefficient of ethane gas, although small, is present and affects the gas diffusion in the solvent.