Absorption of Ethylene from Ethylene–Ethane Gaseous Mixture by AgNO 3 Solution in a Semi-Continuous Process H. R. Mortaheb,* M. Mafi, A. Zolfaghari, B. Mokhtarani, N. Khodapanah and F. Ghaemmaghami Faculty of Chemical Engineering and Physical Chemistry, Chemistry and Chemical Engineering Research Center of Iran, P.O. Box 14335-186, Tehran, Iran Ethylene absorption from an ethylene–ethane gaseous mixture in the silver nitrate solution is studied at different temperatures and concentrations. Unlike the previous studies, in which the absorption was studied by batch processes, a semi-continuous process is applied in the present research. The results show that increase in temperature reduces the amount of absorbed ethylene and absorption time. The amount of absorbed ethylene is increased in solutions with higher concentrations of AgNO 3 , whereas the mole ratio of absorbed ethylene per silver nitrate is decreased by increasing the AgNO 3 concentration. Total absorption is modelled as a function of the temperature and concentration of absorbing solution. The estimated values from the model are in good agreement with the experimental data. L’absorptiondum´ elangegazeuxdel’´ ethyl` ene-´ ethanedansunesolutiondenitrated’argentest ´ etudi´ ee ` adiff´ erentestemp´ eratures et concentrations. Contrairement aux ´ etudes ant´ erieures lors desquelles l’absorption ´ etait ´ etudi´ ee par proc´ ed´ es en lots, un proc´ ed´ e semi-continu a servi pour la recherche actuelle. Les r´ esultats indiquent qu’une hausse de temp´ erature r´ eduit la quantit´ e d’´ ethyl` ene absorb´ ee et le temps d’absorption. La quantit´ e d’´ ethyl` ene absorb´ ee est augment´ ee dans les solutions ayant des concentrations de AgNO3 plus ´ elev´ ees alors que le ratio de moles d’´ ethyl` ene absorb´ es par nitrate d’argent est diminu´ e en augmentant la concentration de AgNO3. L’absorption totale est mod´ elis´ ee en tant que fonction de la temp´ erature et de la concentration de la solution absorbante. Les valeurs estim´ ees ` a partir du mod` ele appuient les donn´ ees exp´ erimentales. Keywords: ethylene absorption, silver nitrate solution, semi-continuous process, gaseous mixture INTRODUCTION G aseous mixtures of olefins/paraffins are produced from dif- ferent processes. The Fischer–Tropsch synthesis produces different gaseous and liquid products, including methane and a mixture of C 2 –C 4 olefins/paraffins (Munson et al., 2001). Mixtures of ethane–ethylene and propane–propylene are pro- duced in ethane cracking and dehydrogenation units, respectively (Bessarabov et al., 1995; Munson et al., 2001). One of the classical methods for separation of olefin from light gaseous mixtures is low-temperature distillation (Nymeijer et al., 2004a). However, it requires a large number of stages and/or high reflux ratios (Munson et al., 2001). Extractive distillation as an alternative separation method requires adding a reagent to enhance the relative volatility of the paraffin with respect to the olefin (Eldridge, 1993; Nymeijer et al., 2004a). Physical adsorp- tion using molecular sieves is an alternative separation method, in which ion exchange molecular sieves such as Ba, Mg, and K zeolites are used (Eldridge, 1993). However, these methods are expensive, suitable for feeds with high percentage of olefins, and also consume large amount of energy. Absorption systems in the form of liquid membranes have gained increasingly interest as promising processes due to their low-energy consumption, high selectivity, and appropriate effi- ciency. Some other advantages of these systems are variety in ∗ Authortowhomcorrespondencemaybeaddressed. E-mailaddress:mortaheb@ccerci.ac.ir Can. J. Chem. Eng. 87:957–964, 2009 © 2009 Canadian Society for Chemical Engineering DOI 10.1002/cjce.20239 | VOLUME87,DECEMBER2009 | | THE CANADIAN JOURNAL OF CHEMICAL ENGINEERING | 957 |