Produção e aplicação de catalisadores a base de materiais fosfatados em reações de esterificação do ácido oleico

Abstract

The use of solid acid catalysts on the production of biodiesel has been highlighted since it was allowed the use of cheap oils or waste cooking oil. It also presents advantages such as no corrosion and reusability. In this work the production of phosphated materials from modified activated carbons and phosphated zirconia was studied, as well as, the production of phosphated zirconia from activated carbons modified with phosphate. The activated carbons were produced from PVA coffee defects, using chemical activation with K2CO3 and H3PO4. The carbons were characterized and tested in the adsorption of methylene blue, wherein the carbon activated with K2CO3 have revealed to be more efficient in the adsorption process (312.5 mg g-1). The carbon activated with K2CO3 was treated with phosphorus tribromide to produce an acid material. The catalysts were characterized by scanning electron microscopy - energy dispersive spectroscopy (SEM-EDS), thermogravimetric analysis (ATG), infrared spectroscopy (FTIR), X-rays diffractometry (XRD) and acidity tests. It was shown that the materials produced have acid properties, with tetragonal structure and thermal stability. Catalytic activity of the materials was tested in the esterification of oleic acid with methanol at 70 and 100°C, using 1:50 molar ratio. At these tests was observed that the influence of the temperature at the efficiency of the reaction, the reactions at 100°C showed the best results. Among the catalysts, the activated carbon treated with PBr3 has showed the best activity, even in reactions at 70°C. The reuse tests showed that most of the catalysts produced in this work have lost activity after the first utilization, but they are active for 3 cycles.