Synthesis of silica nanoparticles and study of its catalytic properties in the preparation of carboxylic esters

Abstract

Silica nanoscale powders were obtained by heat treatment on the waste of laboratory silica gel HF254 available at the warehouse. That white solid was thermally treated at optimal conditions at 700 °C for 4 h and after decomposition of all of the materials, was refluxed with HCl (6 M) for 24 hours. Afterward, the prepared catalyst was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and Brunauer–Emmett–Teller (BET) analysis. The average nanoparticle size was measured 25 nm. So the purpose was investigated on the attributes of the catalyst supported by chloro sulfuric acid and its application in the Fisher esterification reaction as an acid solid catalyst under solvent-free conditions. According to this, different parameters such as the types of alcohols and phenols and carbon chain length were studied by both nano-silica sulfuric acid (NSSA) and silica sulfuric acid (SSA) at the same conditions. In this case, the foundings illustrated esterification in the presence of NSSA was performed at reaction time less than SSA and the production yield of NSSA was higher than SSA. The obtained results in the mentioned method proved silica from the wastes of silica gel HF254 can be employed as a catalyst at the more reaction.