Síntese e obtenção de catalisador à base de vidro soda-cálcico funcionalizado com NaOH para reações de transesterificação na produção de biodiesel e despolimerização do PET em PTA

Abstract

This study aimed to develop and evaluate heterogeneous catalysts produced from recyclable soda-lime vitreous waste, combined with eggshells and NaOH, for application in two environmentally relevant chemical pathways: the transesterification of vegetable oils for biodiesel production and the depolymerization of polyethylene terephthalate (PET) to obtain terephthalic acid (PTA). The proposal is based on the valorization of municipal solid waste through its transformation into sustainable catalytic materials, aligned with the principles of green chemistry and the circular economy. The samples were characterized using various analytical techniques, including Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, laser-induced optical emission spectroscopy (LIBS), X-ray diffraction (XRD), and particle size analysis by laser scattering. The results of these analyses confirmed significant structural and chemical changes in the glass matrix, such as the presence of hydroxylated groups, modification of the silicate network, the elimination of carbonates, and the incorporation of elements such as sodium and calcium, which are directly associated with catalytic activity in basic reactions. Particle size analysis, through statistical analysis of the data, confirmed the good uniformity in sphere size, validating the methodology used in their manufacture. In the catalytic tests, we obtained a 60% methyl ester content in the production of biodiesel from the transesterification of soybean oil, and conversions exceeding 70% in the depolymerization of PET for PTA recovery, even under moderate operating conditions. These results highlight the potential of the developed catalysts as substitutes for conventional catalysts. Future studies aimed at improving their physicochemical properties, as well as optimizing reaction parameters and conditions, could increase their catalytic efficiency.