Paraffins extraction by adsorption employing divalent metal exchanged zeolite

Abstract

Recently, the normal paraffins market has been growing steadily every year as C10-C14 normal paraffins are used as a feedstock for the production of surfactants such as linear alkyl benzene (LAB). One way to obtain this range of normal paraffins is to extract them from middle distillate (kerosene and gas oil) by adsorption technique. In this research, three types of divalent cation (Ca2+, Mg2+, and Sr2+) were exchanged with sodium in zeloite NaA (4A). Three exchanged zeolite A samples obtained, 57% Mg-Na-A, 53% Ca-Na-A, and 54% Sr-Na-A, were used for normal paraffins adsorption. Two sets of experiments consisting of thermogravimetric and breakthrough curve experiments were used to test these three samples. From thermogravimetric analyses, it is found that the larger the size of the cations exchanged into the zeolite NaA (Mg<Ca<Sr), the more difficult the desorption of normal paraffins. This is most probably due to the confinement effect. For the breakthrough curve experiment, the magnesium form of zeolite A which was expected to be a better adsorbent turned out to have a lower capacity than those of calcium and strontium. This may be due to the disruption of the structure during the dehydration of the Mg-Na-A before adsorption.