Preparação e caracterização de catalisadores ácidos zircônia sulfatada para aplicação na esterificação do óleo de algodão.

Abstract

Biodiesel stands out as a viable alternative to petroleum diesel. This one biofuel from renewable raw materials stands out for being biodegradable, safe, low-polluting (low carbon dioxide and sulfur emissions) and for generating economic opportunity for small and medium farmers. Thus, the objective of this proposal was to obtain zirconia (Z1O2) by combustion synthesis and to make a comparative analysis regarding the structure and morphology of a commercial monoclinic zirconia and to investigate the sulfation aiming to obtain acid catalysts to be evaluated in the esterification of cotton to obtain biodiesel. Synthetic Z1O2 was obtained by 15 g batch combustion reaction of the product, used as precursor of zirconium IV n-propoxide and urea. Commercial Z1O2 was supplied by the company Saint-Gobain Zirpro. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), textural analysis by nitrogen adsorption (BET), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TG / DrTG) and differential thermal analysis (DTA), X-ray fluorescence spectroscopy (EDX), particle size distribution and gas chromatography. The synthesized Z1O2 showed the formation of the majority monoclinic phase with traces of the orthorhombic phase, with crystallite size 16 nm and crystallinity 57%. For the commercial sample, only the single phase was identified. monoclinic with crystallite size 39 nm and crystallinity of 86%. With the process sulfation and calcination of both Z1O2 (synthesized and commercial), traces of the tetragonal phase, typical of S0427Zr02, with the permanence of the majority monoclinic phase in the two sulfated samples. The sizes of crystallites and crystallinities resulted in a decrease in their values ​​with sulfation, Featuring 16 nm crystallite size and 44% crystallinity for the S0427Zr02 synthesized and crystallite size 27 nm and crystallinity 67% for the S0427Zr02 commercial. Both samples presented homogeneous morphology, consisting of very fine particles of approximately spherical shape. Comparing the samples among them, it was found that the synthesis by combustion reaction was efficient to obtain monoclinic Z1O2 nanoparticles with traces of the orthorhombic phase with finer particle morphology than commercial monoclinic Z1O2. Chromatographic analysis indicated conversion of 26 and 28% in methyl esters to ZK) 2 as synthesized and commercial, and maximum conversion around 65 and 91% in methyl esters to synthesized and commercial S042 "/ Zr02, respectively. The results indicated that sulfation increases acidity and contributes significantly to increased conversion, indicating that S042 "/ Zr02 6 is a promising catalyst for biodiesel esterification.