Batch and fixed bed column selective adsorption of C6, C8 and C10 linear α-olefins from binary liquid olefin/paraffin mixtures onto 5A and 13X microporous molecular sieves

Abstract

The separation of gaseous olefin/paraffin mixtures by physical adsorption and π-complexation chemical adsorption has been widely investigated, while studies on the adsorption of liquid olefin/paraffin are much rarer. One of the most important reasons is that it is difficult to determine the actual adsorption capacity of liquid phase adsorption directly through experiments, and the study of liquid olefin/paraffin mixtures adsorption capacities has not been sufficiently systematic. In this paper, the adsorption of C6, C8 and C10 linear α-olefins onto 5A and 13X molecular sieves from binary liquid olefin/paraffin mixtures in batch and fixed bed column systems was systematically investigated.In batch experiments, a measurement method of actual adsorption capacity was established, and the actual adsorption capacities of 5A and 13X were determined by the liquid phase concentration difference and pore volume correction with the help of gas chromatography (GC) and physisorption apparatus. The adsorption selectivity was obtained through experimental data and the binary liquid adsorption theory. Experimental data were fitted to the Freundlich and Langmuir isotherms to determine the adsorption characteristics. The adsorption kinetics were well fitted with pseudo-second-order and Crank models. In the fixed bed column experiments, breakthrough curves were obtained and the dynamic adsorption characteristics were analyzed through breakthrough curves. The effects of operational conditions, such as adsorbents, flow rate and feed concentration on the column dynamics were examined. Both Thomas and Yoon-Nelson models gave satisfactory fits to the experimental data of dynamic adsorption in a fixed bed column.