Antonio Osimar Sousa da Silva

Flash Pyrolysis of Oleic Acid as a Model Compound Adsorbed on Supported Nickel Catalysts for Biofuel Production

Flash pyrolysis of oleic acid was studied over 10 wt.% nickel catalysts supported on silica and alumina. The catalysts were impregnated with 10 wt.% oleic acid. The dried precursors and the catalysts containing oleic acid were characterized by thermogravimetric analysis. The calcined catalysts were analyzed by X-ray diffraction (XRD) and temperature programmed reduction (TPR). Samples containing adsorbed oleic acid were submitted to flash pyrolysis up to 650 °C. Whereas pyrolysis of oleic acid without catalyst converted only about 10%, the pyrolysis of oleic acid adsorbed on catalysts allowed practically a complete conversion. NiO/alumina yielded a higher amount of liquid hydrocarbons than NiO/silica. The main products obtained with NiO/silica were 1-alkenes, whereas the main products obtained with NiO/alumina were alkene isomers and aromatics. Small amounts of oxygenated compounds were also observed, principally alcohols. The flash pyrolysis of oleic acid adsorbed on different catalyst surfaces appears as a useful way to distinguish activity trends of different catalyst samples.

Flash pyrolysis of myristic acid adsorbed on supported nickel catalysts for biofuel production

AbstractnThe present work is part of a more general project aiming at studying the decomposition products formed during the pyrolysis of fatty compounds adsorbed on solid catalysts. It deals with the decomposition of myristic acid in contact with nickel-supported catalysts. The pyrolysis was performed at 650xa0°C in a flash mode. The products were analyzed on-line through a GCMS setup. The catalysts were prepared by impregnation with nickel nitrate, dried at 110xa0°C and heat treated at 600xa0°C before use. Solid myristic acid was added at room temperature to the dehydrated catalyst by mechanical mixing followed by heat treatment at 120xa0°C under intense manual mixing, in order to allow the liquid myristic acid to wet the catalyst surface. The catalysts precursors and the catalysts containing myristic acid were characterized by DTG, and the catalysts in their oxide form were characterized by TPR and XRD. The catalysts containing adsorbed myristic acid were also characterized by FTIR. Compared with Ni/silica producing a high amount of linear 1-olefins during flash pyrolysis, the contents of deoxygenated products, of poly olefins and aromatics, were higher with the Ni/alumina catalyst. The presence of carboxylic acids with a chain length between 6 and 12 C in the pyrolysis products on the Ni/silica catalyst suggests that the cracking along the carbon chain occurred parallel to reactions of decarbonylation and decarboxylation. We also found a direct demethylation route with the Ni/silica catalyst in this experiment.

Preparation and characterization of Pt-dealuminated Y zeolite by TG/DTA and TPR

Monometallic catalysts containing Pt supported on dealuminated Y zeolite were prepared by impregnation with a solution containing H2PtCl6·6H2O cationic complexes. The catalysts were calcined and characterized by X-ray fluorescence (XRF), X-ray diffraction (XRD), simultaneous thermogravimetry/differential thermal analysis (TG/DTA), temperature programmed reduction, physisorption of nitrogen, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy dispersive X-ray spectroscopy (EDX). The XRD results showed that zeolite Y maintained its crystalline structure throughout the dealumination and metal incorporation processes. However, the relative crystallinity of the various samples was reduced upon impregnation. Furthermore, the XRD diffractograms, the SEM and TEM micrographs, and EDX spectra for the impregnated samples presented evidence for the presence of Pt oxides. The adsorption isotherms of the nitrogen physisorption showed the existence of micropores and mesopores within the Pt/Y zeolite. Temperature programmed reduction profiles suggest that the reduction temperature of Pt depends on the location of the metal within the zeolitic structure. The reduction peaks can be attributed to cations located in the large cavities, sodalite cages, or hexagonal prisms. The TG/DTA analyses showed the endothermic decomposition of the Pt complexes deposited on the zeolite during impregnation.

Immobilization of the enzyme invertase in SBA-15 with surfaces functionalized by different organic compounds

The search for appropriate supports for enzyme immobilization has attracted increasing interest in the field of biocatalysis. Immobilized enzymes are catalysts of enormous industrial interest because they combine the advantages of heterogeneous catalysis with the high selectivity and mild operational conditions of enzymes. This study evaluated the use of different organic molecules as functionalizing agents anchored on the silanol groups present on the surface of mesoporous materials such as SBA-15. This modification aims to increase the interaction of the enzyme invertase to the support, allowing for a greater amount of this biocatalyst to be immobilized. The hexagonal mesoporous material SBA-15, which has pores in the range of 40–60xa0Å, was synthesized and modified by the following organic compounds: trimethoxyphenylsilane, vinyltrimethoxysilane and 3-aminopropyltriethoxysilane (APTES). APTES showed the best results in increasing the anchoring of enzymes on the material’s surface, providing a specific amount of enzyme loaded onto the surface of approximately 80% and, thus, showing successful functionalization.

Synthesis and characterization of mesoporous materials containing cerium, lanthanum and praseodymium by nonhydrothermal method

AbstractnMesoporous molecular sieves the type MCM-41 (Mobil Composition of Matter of number n) modified with rare earth elements cerium, lanthanum and praseodymium (CeMCM-41, LaMCM-41 and PrMCM-41) was synthesized via direct and nonhydrothermal method at 80xa0°C and characterized by X-ray diffraction, nitrogen absorption (BET/BJH), thermal analysis (TG/DTG), infrared spectroscopy (FT-IR), scanning electron microscopy, transmission electron microscopy and acidity measurements. The catalytic activity of the synthesized catalysts was tested in an esterification reaction of oleic acid with methanol. The reaction was carried out at 130xa0°C with an alcohol/acid molar ratio of 8 and 5 wt% catalysts for 2xa0h. Among all of the catalysts tested in this study, the most efficient was LaMCM-41 affording over ca. 37 wt% of conversion. Hence, the catalyst LaMCM-41 was used for the detailed study on the effect of any reaction parameters such as acid/alcohol molar ratio, temperature and reaction time to obtain the conditions for maximum conversion.Graphical Abstract

Análise quantitativa das zeólitas ferrierita, ZSM-5 e mordenita presentes em amostras sintetizadas

In studies for obtaining zeolitic materials common to the formation of mixtures of crystalline phases due to the relative stability of these materials in the medium used in the synthesis. Thus, it is extremely important to quantify the various phases present in the system to optimize methods of synthesis of a zeolite without determining the presence of contaminants. Specifically, it was found that during the synthesis of zeolites ZSM-5(MFI), mordenite (MOR) and ferrierite (FER) in various experimental conditions, is the formation of binary mixing phases (FER + MOR) and (FER + MFI), sometimes ternary (FER + MOR + MFI). The purpose of this work was to perform various binary mixtures at various percentages of these materials in order to obtain a methodology to quantify the presence of each of the stages (FER, MOR and MFI) samples synthesized under different experimental conditions. With this objective, physical mixtures were prepared with different contents of the phases MFI, MOR and FER, from highly crystalline samples of each phase. These known compositions phases were analyzed by X-ray diffraction to quantify the areas of the peaks characteristic of each material, thus being able to obtain a ratio of the percentage of phase/area of each blend component.