Kinetics and mechanisms of adsorption/desorption of the ionic liquid 1‐buthyl‐3‐methylimidazolium bromide into mordenite

Abstract

AbstractBACKGROUNDKinetics of adsorption and desorption associated with diffusion mechanisms is of crucial importance to use zeolites as catalysts. In particular, diffusion of ionic liquids (IL) is of interest when using them as solvent for reactions or preparing composite IL–Zeolite. This work investigated the kinetics of adsorption/desorption of 1‐buthyl‐3‐methylimidazolium bromide ([BMIM]+Br−) into mordenite (MOR), a channel‐like zeolite.RESULTSThe adsorbed IL is characterized and quantified using infrared spectroscopy (FTIR), thermogravimetrical analysis (TGA) and CHN elemental analysis. The results show rapid adsorption of c. 0.7 mol of [BMIM]+Br− per gram of MOR but most of it remains in the pores of the zeolite upon desorption because only 9% is desorbed. CHN and TGA also suggest that adsorption of [BMIM]+Br− into the ammonium form of MOR can follow an ionic exchange mechanism. Experimental results can be fitted to a pseudo‐second‐order kinetic equation.CONCLUSIONThe kinetics and mechanisms of adsorption and desorption of [BMIM]+Br− into MOR have been studied. Adsorption kinetics is relatively quick; but only partial desorption occurs probably due to the strength of the [BMIM]+Br−–MOR interaction. The observed differences between the adsorption of [BMIM]+Br− into the different forms of MOR give important information on the interaction mechanisms. © 2015 Society of Chemical Industry