Cerium oxide (Ce100), molybdenum oxide (Mo100), and a material containing Ce and Mo (CeMo) were synthesized by the Pechini method, using glycerol as a polyol. These materials were applied for fructose conversion in an aqueous medium. The characterization results show the formation of cerium molybdate (Ce₂(MoO₄)₃) for CeMo. Ce100 presented good thermal stability, and Mo100 sublimation of MoO₃ and polymolybdates was verified. CeMo exhibited a mass loss of 19%, associated with the sublimation of MoO₃ and polymolybdate species. Additionally, the existence of Bronsted and Lewis acid sites was confirmed, and the addition of Mo to Ce was an efficient strategy to increase the acidity. Regarding the catalytic activity (150 °C and 0.5 to 6 h), Ce100 exhibited low conversions and high selectivity to 5-hydroxymethylfurfural (5-HMF). For Mo100, high conversions, with a significant formation of insoluble materials, were detected. For CeMo, beyond the high activity, a lower formation of insoluble materials was noted. In this case, selectivity toward products from the retro–aldolic route and 5-HMF were obtained. These results indicate that the main factor influencing fructose conversion is an adequate combination of the acid sites. Recycling experiments were carried out, and stability was observed for four cycles, confirming the robustness of this system.

Pure and mixed oxides were synthesized using three methods, namely, coprecipitation, hydrothermal treatment using CTAB and Pechini treatment using glycerol, and investigated for the transformation of fructose, aiming to determine the influence of textural, structural, and acid-base properties on conversion and selectivity. All systems led to fructose conversion in an aqueous medium, and the factors that influenced the transformation were the textural and structural properties, as well as the number of acid sites present in the catalysts. The best conversions were observed using mixed oxides, highlighting SnNb (CTAB) and SnNb (GLY), showing the importance of the modulation of properties using the synthesis method. All systems were selective mainly for 5-HMF (5-hydroxymethylfurfural) and, to a lesser extent, for the products of the retro-aldolic route, and this selectivity was preserved, regardless of the catalytic system used.

The modification of fatty substrates using heterogeneous catalysts have extensive industrial application and has an emphatic position in a sustainable context. Herein ruthenium, nickel, cobalt and copper-doped ruthenium, supported on hypercrosslinked polystyrene (HPS) catalysts were prepared by wet impregnation, characterized and applied on the modification of canola fatty acid methyl esters (FAME). The characterization showed a dispersive effect of doping metals over the ruthenium particles, the presence of acid sites and overall surface morphology, which allows targeting potential applications. The chosen modifications consisted of hydrogenation, hydroformylation, oxidative cleavage and deoxygenation, resulting in superb catalytic activities of over 99% conversions for hydrogenation and deoxygenation. The simplicity of the canola FAME composition allows the understanding of the catalytic processes and allows the upscale of more complex FAME matrixes. Finally, the obtained data stimulates further optimization studies for each application with a variation on the catalysts and the usage of residual fatty substrates, greatly enhancing the sustainability profile of the systems.

RESUMO: Atualmente, o uso de fontes renováveis e sustentáveis para produzir energia e produtos químicos associados ao desenvolvimento de catalisadores heterogêneos é uma estratégia promissora, pois esses possuem a vantagem de serem recuperados e reutilizados, diminuindo custos e contaminações no produto. Nesse sentido, açúcares derivados de biomassa, como glicose e frutose, podem ser empregados como blocos de construção para fabricação de insumos químicos, que podem complementar ou substituir alguns derivados petroquímicos e que apresentam grande potencial industrial e alto valor agregado. Dessa forma, a isomerização da glicose à frutose em meio aquoso foi estudada utilizando óxidos de metais SnO2, MoO3 e SnO2/MoO3 comparativamente à reação sem catalisador. Foram avaliadas as atividades catalíticas em termos de conversão e rendimento à frutose nas temperaturas de 50 e 70º C com tempos de reação de 0,25 a 6 h. Os catalisadores foram caracterizados utilizando técnicas como espectroscopia de absorção na região do infravermelho (FTIR), análise termogravimétrica (TG/DTA) e difração de raio-X (DRX). Os resultados demonstram que o fator principal que influência a conversão da glicose são os sítios ácidos presentes nos sistemas catalíticos. Com esse estudo pode-se constatar que o óxido de molibdênio e o óxido misto conduziram a altas conversões, porém o óxido de molibdênio apresentou melhores resultados em termos de rendimento à frutose. Além disso, foram identificados e quantificados outros produtos minoritários como gliceraldeído e piruvaldeído. PALAVRAS-CHAVE: Biomassa. Catálise. Monossacarídeos.