Avaliação de catalisadores de Ti e Zr suportados em argilas porosas heteroestruturadas (PCH) aplicados às reações de esterificação de ácido caprílico com 2-etilhexanol

Abstract

In order to obtain products from renewable raw materials, in this work solid catalysts were obtained that were used to obtain bioproducts. The montmorillonite clay was modified to form a porous structure, porous clays heterostructures (PCH), which was used as support for the catalysts. In the preparation of these materials, the sol-gel methodology was used and the incorporated metals were Ti and Zr with molar ratios Si/Ti and Si/Zr equal to 5. The porous materials such as PCH-Si/Ti and PCH-Si/Zr were synthesized using tetraethylorthosilicate, as silica source, and as active phase the metals Ti and Zr, being titanium tretachloride and zirconium propoxide IV sources. The time for catalyst synthesis was 192 hours. The support (PCH) and the catalysts PCH-Si/Ti and PCH-Si/Zr, were characterized by X-Ray diffraction (XRD), adsorption and desorption of N2 by the BET method (Brunauer – Emmett – Teller) and temperature programmed ammonia desorption (TPD). The catalysts had their catalytic activity evaluated in the esterification reaction of caprylic acid with 2-ethylhexanol alcohol using the molar ratio 1:4 and 5% of catalyst in relation to the acid mass. The reactions were carried out using the following temperatures: 80, 100 and 120°C. The acidity of caprylic acid and the products obtained was determined by the acidity index and the samples were characterized by FTIR. The conversions of the products obtained using the PCH-Si/Ti and PCH-Si/Zr catalysts were compared with the commercial catalyst Amberlyst-15, being observed that the PCH-Si/Ti and PCH-Si/Zr catalysts were in a range of conversion between 70-78%, while the Amberlyst-15 catalyst showed a 99% conversion, resulting in good catalytic activity of the catalysts used in this evaluation.