A novel separation process for olefin gas purification: Effect of operating parameters on separation performance and process optimization

Separation of propylene–propane mixtures using facilitated transport membrane is potentially a novel separation process for olefin gas purification. The main purpose of this study was to find optimum values of the process parameters using the Taguchi approach. The Taguchi method was selected as the statistical technique since it allows the main effects to be estimated with a minimum number of experimental runs. Moreover, it makes use of fractional factorial and orthogonal arrays to identify the factors and the optimum factor setting for each experimental run. Trans-membrane pressure and carrier concentration were two influential parameters that affect the separation performance of the present membrane system. These control factors in three levels were considered in the Taguchi analysis. L9 orthogonal array has been used to determine the signal-to-noise (S/N) ratio. Analysis of variance (ANOVA) was used to determine the optimum conditions. It indicated that carrier concentration has the most contribution (72%) in the membrane separation of propylene–propane mixture. Moreover, to achieve an optimum operating condition, trans-membrane pressure and carrier concentration should be set at 120 kPa and 20 wt.%, respectively. According to the Taguchi approach, by setting control factors at optimum values a product with 99.801 (vol.%) propylene was obtained. A verification test was also performed to check the optimum condition. Experimental results confirmed optimum values obtained by the Taguchi analysis and showed that at optimum operating conditions, a product with 99.63 (vol.%) propylene was obtained.