http://hdl.handle.net/11422/59 Tue, 21 Jul 2026 12:14:54 GMT 2026-07-21T12:14:54Z http://hdl.handle.net/11422/29696 Title: Carbetos metálicos para a hidrogenólise do 5-Clorometilfurfural a 2,5-Dimetilfurano: um precursor do pxileno verde Author(s)/Inventor(s): Coutinho, Sofia Guerson Gonçalves Advisor: Ferraz, Camila Palombo Abstract: This work investigates the application of metal-based catalysts in the conversion of biomass-derived platform molecules into higher value-added compounds. The hydrogenolysis of 5-chloromethylfurfural (CMF) and 5-hydroxymethylfurfural (HMF) to produce 2,5-dimethylfuran (DMF) was studied. DMF is a promising compound both as a biofuel and as an intermediate to produce green p-xylene. CMF stands out as an alternative to HMF due to its easier separation and high yields from different lignocellulosic biomass sources. In this context, palladium supported on carbon (5% Pd/C) and transition metal carbides were evaluated as catalysts, particularly molybdenum carbide (Mo₂C) and tungsten carbide (W₂C), aiming at lower-cost catalytic alternatives compared to noble metals. The catalysts were synthesized and characterized using techniques such as X-ray diffraction (XRD), scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM–EDS), temperature-programmed carburization (TPC), Raman spectroscopy, and CO chemisorption. Catalytic tests were carried out in a reactor under a hydrogen atmosphere, and the reaction products were analyzed by gas chromatography. The results indicate that 5% Pd/C exhibited high catalytic activity for hydrodeoxygenation (HDO) and hydrodechlorination (HDC) reactions, achieving 100% conversion and selectivity higher than 60% toward DMF from both HMF and CMF. Transition metal carbides showed relevant catalytic properties for the HDC reaction of CMF, with selectivity toward the formation of an important intermediate for DMF production. Publisher: Universidade Federal do Rio de Janeiro Type: Dissertação Thu, 01 Jan 2026 00:00:00 GMT http://hdl.handle.net/11422/29696 2026-01-01T00:00:00Z http://hdl.handle.net/11422/29695 Title: Arquiteturas porosas à base de sílica como plataformas para encapsulamento de ftalocianinas: uma abordagem versátil para aplicações fotoquímicas avançadas Author(s)/Inventor(s): Santos Filho, Ricardo Pinheiro dos Advisor: Ribeiro, Emerson Schwingel Abstract: Development of functionalized nanomaterials with photoactive properties has attracted growing interest in fields such as medical therapies and environmental technologies. In this work, porous silica-based core–shell architectures were prepared, in which the core consists of magnetite and the shell of mesoporous silica, employed as platforms for the encapsulation of zinc phthalocyanine (ZnPc), a photosensitizer with recognized efficiency in singlet oxygen generation under visible light irradiation. Immobilization of ZnPc in the silica matrix pores aims to enhance its stability in aqueous and biological media, while preserving its photodynamic activity by minimizing molecular aggregation that reduces the quantum efficiency of the free material. The nanoparticles and photosensitizer obtained were characterized by ELEMENTAL ANALYSIS (CHN), X-RAY FLUORESCENCE (WDXRF), SCANNING ELECTRON MICROSCOPY/ENERGY-DISPERSIVE X-RAY SPECTROSCOPY (SEM/EDS), XRAY DIFFRACTION (XRD), FOURIER-TRANSFORM INFRARED SPECTROSCOPY (FTIR), RAMAN SPECTROSCOPY, UV–VIS SPECTROSCOPY and FLUORESCENCE EMISSION SPECTROSCOPY, as well as by direct and indirect methods for singlet oxygen characterization, confirming functionalization, encapsulation and the optical, structural and elemental properties of the system. Preliminary assays evaluated the efficiency of the materials in two contexts: singlet oxygen generation for photodynamic therapy (PDT) and photodegradation of organic dyes as a model for the treatment of recalcitrant effluents. The results indicate that silica-based core–shell architectures (Fe3O4@SiO2) functionalized with ZnPc represent a promising approach, combining structural stability, photosensitizing efficiency and multifunctional potential for advanced photochemical applications in biomedical and environmental contexts. Publisher: Universidade Federal do Rio de Janeiro Type: Dissertação Mon, 27 Apr 2026 00:00:00 GMT http://hdl.handle.net/11422/29695 2026-04-27T00:00:00Z http://hdl.handle.net/11422/29617 Title: Síntese de tiazóis fundidos a partir de indeno e β-dicetonas cíclicas promovida por ácido tribromoisocianúrico: uma abordagem telescópica Author(s)/Inventor(s): Crispim Neto, Jaime Advisor: Mattos, Marcio Contrucci Saraiva de Abstract: In this work, the use of tribromoisocyanuric acid (TBCA) was explored for the in situ formation of α-bromocarbonyl intermediates in the telescoped synthesis of 2-aminothiazoles fused to partially saturated rings, which have gained increasing interest in medicinal and agrochemical chemistry. Seven examples of 2-amino-5,6-dihydrobenzo[d]thiazol-7(4H)-ones were synthesized in 15–83% yield through the bromination reaction of dimedone or 1,3-cyclohexanedione with TBCA catalyzed by p-toluenesulfonic acid, followed by the Hantzsch reaction with thioureas, without the isolation of any reaction intermediates, thus saving one isolation step. The telescoped synthesis of 13 examples of 2-aminoindenothiazoles was achieved by reacting indene with TBCA, promoting sequential co-bromination/oxidation reactions in water, followed by reaction with various monosubstituted thioureas, affording the heterocycles in 19–57% yield after a single isolation step. This reaction was evaluated in comparison with other current methodologies and classical routes using green metrics such as atom economy (AE), atomic efficiency (AEf), reaction mass efficiency (RME), and optimization efficiency (OE). It was demonstrated that, for selected cases, the difference between stepwise synthesis and telescoped synthesis resulted in 42–148% higher final product yield for the step-economical process. In vitro and in vivo assays (in soybean seedlings) were performed with the synthesized fused thiazoles to evaluate their activity against Meloidogyne incognita at its second juvenile stage, a highly damaging plant-parasitic nematode affecting commercially important crops. Among the investigated compounds, N-(pyridin-2-yl)-8Hindeno[1,2-d]thiazol-2-amine exhibited nematicidal activity comparable to that of a commercially used substance, with low phytotoxicity, making it a promising candidate for the development of new nematicides. Publisher: Universidade Federal do Rio de Janeiro Type: Tese Mon, 11 May 2026 00:00:00 GMT http://hdl.handle.net/11422/29617 2026-05-11T00:00:00Z http://hdl.handle.net/11422/29616 Title: Acoplamento reativo-hidrodinâmico na dissolução de incrustações de sulfato de bário: desenvolvimento de sistema dinâmico em escoamento Author(s)/Inventor(s): Silva, Gabriel Nunes Nogueira e Advisor: Silva, João Francisco Cajaiba da Abstract: The dissolution of mineral scale in industrial systems is traditionally evaluated through batch experiments, in which the solid is immersed in a dissolving solution and removal is monitored over time by ex situ analyses, with periodic quantification of the dissolved concentration or residual mass. In this approach, results are typically expressed as final removal efficiency or percentage dissolution after a given contact time. Although useful for preliminary comparison of formulations, such metrics fail to capture the complexity of the coupling between chemical and hydrodynamic phenomena under realistic flow conditions. In this work, a novel methodology was developed for investigating the dissolution of barium sulfate (BaSO4) under flow conditions. The experimental arrangement consists of a column filled with a structure of 316 stainless steel spheres interspersed with BaSO4, forming a reactive packed bed that simulates a solid obstruction. The controlled injection of a dissolving solution (DTPA or EDTA) through this bed promotes progressive dissolution of the solid while the obstruction structure evolves throughout the experiment. This process is monitored in an integrated manner using in situ techniques, including infrared spectroscopy for quantification of the dissolved species and hydrodynamic analysis based on continuous differential pressure measurements and estimation of bed permeability. This configuration enables the acquisition of temporal concentration profiles, instantaneous dissolution rates, and the hydrodynamic evolution of the system over time. The methodology allowed the identification of distinct behavioral regimes associated with distributed bed dissolution and the formation of preferential flow paths, highlighting the determining role of hydrodynamics in overall dissolution efficiency. It was observed that, at higher temperatures, although complexation is thermodynamically favored, the more rapid formation of preferential flow paths reduces effective solution-solid contact, limiting the progression of BaSO4 removal. At lower temperatures, in contrast, channeling develops more slowly, promoting more homogeneous permeation of the dissolving solution through the bed. This hydrodynamic behavior compensates for the intrinsically lower chemical efficiency and may result in total dissolution values comparable to those obtained under more thermodynamically favorable conditions. These results demonstrate that dissolution configurations achieving equivalent total dissolution may exhibit significantly different spatial and dynamic dissolution distributions, as reflected in the hydrodynamic and kinetic measurements obtained under continuous flow conditions. Additionally, a phenomenological model based on physical principles was proposed to quantitatively describe the coupling between chemical dissolution and permeability evolution, incorporating the effects of preferential flow path formation into a dissolving efficiency metric. The methodology was validated according to widely adopted metrological performance criteria, demonstrating its repeatability, sensitivity, and applicability. The results establish a more realistic and discriminating approach for the evaluation and selection of dissolving agents under continuous flow conditions, bridging laboratory-scale experimentation and real-world scale removal scenarios. Publisher: Universidade Federal do Rio de Janeiro Type: Tese Thu, 01 Jan 2026 00:00:00 GMT http://hdl.handle.net/11422/29616 2026-01-01T00:00:00Z