MnO۲/Zeolite as a New Synthetic Nanocomposite for the Desulfurization of Thiophene

Over the past years, production of clean fuel has become an important issue from an environmental point of view. To obtion such clean fuel, we studied the role of adsorption/oxidation of MnO۲/zeolite nano composites under mild conditions. Zeolites with porous structure are very promising in adsorption/removal of various componds. Also manganese dioxide (MnO۲) with different crystallographic forms (hollandite (α-MnO۲), pyrolusite (β-MnO۲), ramsdellite (γ- MnO۲), akhtenskite (ε-MnO۲), birnessite (δ-MnO۲) and nsutite (λ-MnO۲)) has attracted considerable attention due to high catalytic activity, facile synthesis, etc [۱, ۲]. In this work, birnessite (δ-MnO۲) with layer structure was prepared by the reaction of permanganate with H۲C۲O۴ at ۳۶۳ K, and dried at ۳۷۵ K [۳]. Then MnO۲/zeolite nano composites were prepared by solid-state disperssion (SSD) methode. Different types of zeolite (Y, Fe-modified clinoptilolite (FeZ) and Cu-modified clinoptilolite (CZ)) were employed as supports for δ-MnO۲ nanoparticles and their catalytic activity were investigated in the adsorption/oxidation of thiophene from a model fuel at ۲۹۸K. The samples were characterized by X-ray diffraction (XRD), infrared spectroscopy (FT-IR) and Scanning Electron Microscopy (SEM). The XRD analyses confirmed the formation of pure tetragonal structured δ- MnO۲. The average diameter was found to be ۱۸.۱ nm according to the Scherer equation. The catalytic activity of nano composites increased in the order of MnO۲/CZ ˂ MnO۲/Y ˂ MnO۲/FeZ. It is anticipated that the adsorption of thiophene takes place via the π-interaction between the adsorbent and thiophene molecules. Actually formation of π-complex between various sulfur and nitrogen containing compounds, olefins and π- electron-rich componds with adsorbent is a common process [۴]. The employment of higher contents of MnO۲ (from ۰.۰۵g to ۰.۱g) in nano composites decreased the removal effeciency of thiophene.Fuel, zeolite, MnO۲, thiophene, catalytic activity, π-complex