Adsorption/desorption of 2,2,4-trimethylpentane on MCM-36 zeolite functionalized by acidic ionic liquid

Abstract

The facile desorption of products from the reaction sites is crucial to the reaction selectively and catalyst life. In the alkylation process of isobutane and olefine, the product is need to remove from the reaction sites timely so as to inhibit the sequential side reactions and improve the catalyst life. MCM-36 was modified by immobilizing ionic liquid [BTPIm][HSO4] (1-buty-3-(3-triethoxysilane)-propyl imidazolium hydrosulfate) so as to provide an effective way to improve the desorption of product 2,2,4-trimethylpentane from the reaction sites. The adsorption/desorption behaviors of 2,2,4-trimethylpentane on MCM-36 or ionic liquid immobilized MCM-36 were studied systematically by an intelligent gravimetric analyzer. The results showed that a decease adsorption capacity of 2,2,4-trimethylpentane was obtained after grafting [BTPIm][HSO4]. Langmuir–Freundlich model described the adsorption isotherms well. The ionic liquid immobilization led to a low isosteric adsorption heat. It indicated that a weaken interaction between adsorbate and adsorbent was obtained by the grafting of ionic liquid. The kinetics research results showed that the adsorption/desorption process was limited by the surface adsorption step. An increase of desorption rate constant and a decrease of adsorption sites were observed after the IL immobilization. It suggested that the ionic liquid loading was helpful to improve the desorption of 2,2,4-trimethylpentane from the reaction surface.