Preparation and Catalytic Properties of Various Oxides and Mesoporous Materials Containing Niobium and Sulfate Ions, in the Etherification Reaction of 2-Naphtol

Abstract

Several types of solid acid catalysts were prepared based on oxides like (ZrO 2 , TiO 2 , HfO 2 , MCM-41 and SBA-15), using two main preparation methods: the precipitation and the sol-gel methods. Each catalyst was subjected to two types of impregnations: sulfate ions using sulfuric acid as precursor and niobium using niobium oxalate as precursor. These prepared catalysts were tested in the etherification reaction of 2-naphtol, where the catalysts showed both acidic and redox properties. The acidic character was manifested through the formation of 2-butoxynaphtalene (with moderate yields) when oxide is sulfated, and the redox character (when impregnated with niobium) manifested through the formation of the interesting product 2-ethylnaphtofuran (with low yields) and other products that were a result of oxidative coupling of two 2-naphtol molecules (binol and acetal of binol). However despite the effort, several attempts to increase the yield of 2-ethylnaphtofuran did not work. All products prepared were obtained in pure form and characterized by 1 H and 13 C NMR, GC and MS.