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The TiO2/MCM-41 nanomaterials were synthesized by impregnation with an excess solvent with different percentages of titanium dioxide. They were used for catalytic degradation of Benzene Toluene Ethylbenzene and Xylenes (BTEX) in the presence of hydrogen peroxide in aqueous media. The obtained materials were characterized by X-ray Diffraction, nitrogen adsorption-desorption using the BET method and Fourier Transform Infrared Spectroscopy. The nanostructured phase of the hexagonal ordered materials was obtained even after modification with titanium oxide and calcination. The characterizations have proven the effectiveness of the synthesis method used to incorporate titanium with anatase structure impregnated in the nanoporous of the MCM-41 material. Anatase is the main active phase of TiO2 to oxidize organic compounds. The catalytic evaluation wascarried out in a semi-bath reactor with 20 mL of a mixture containing BTEX (100 mg/L), hydrogen peroxide (2.0 mol/L) and TiO2/MCM-41 (2.0 g/L) in aqueous media. The reactions were carried out at a temperature of 60°C for 5 hours, and the analyses were performed by gas chromatography with a photoionization detector and headspace sampler. The catalytic tests showed satisfactory results with more than 95% of conversion, where the catalyst 48%TiO2/MCM-41 presented higher performance.

The preparation, characterization and application of materials based on montmorillonite natural clay containing aluminum polyhydroxocomplexes of Keggin type ions (Al13) as intercalating agent and h...

The vast majority of fuels used today are derived from non-renewable sources, causing climate change on the planet. In addition to the problems caused by these energy sources, there are processes for the refining of raw material, such as oil, where high-cost synthetic catalysts are used. In this work, vermiculite was used as catalyst and support for zinc oxide in the pyrolysis of licuri oil. Four catalysts were synthesized: zinc oxide, vermiculite supporting zinc oxide 1 and 6% (VZn1 and VZn6) and calcined vermiculite. The catalysts were characterized by X-ray diffraction analysis, X-ray fluorescence spectrometry, thermal analysis and nitrogen adsorption/desorption. The activation energy was determined using the Kissinger-Akahira-Sunose (KAS) kinetic model. The emitted gas analysis in the deoxygenation study was performed by thermogravimetric analysis coupled with Fourier Transfer Infrared Spectrometer (TGA-FTIR). Pyrolysis was performed in a pyrolyzer coupled to chromatography with mass spectrometry (Py-GC/MS) for the determination of the products. The catalysts showing the highest catalytic activity were vermiculite and VZn1, with activation energies lower than that for thermal pyrolysis. VZn1 showed higher activity in the formation of hydrocarbons (43.5%) by deoxygenation, indicating that zinc oxide associated with vermiculite is an option for the catalytic pyrolysis of biomass.

Bimodal silica and aluminosilicate materials containing mesopores and macropores were synthesized by hydrothermal method using sodium silicate, aluminum nitrate, P123 triblock copolymer, n-decane, hydrochloric acid and water. The uncalcined silica compound was previously characterized by thermogravimetry, and the calcined materials were characterized by X-ray diffraction, infrared absorption spectroscopy, and scanning electron microscopy. The obtained materials have bimodal characteristics with mesopores and macropores in their structures, which pores are ideal for processing bulky molecules, such as hydrocarbons present in heavy oil. In this work, the synthesized silica and aluminosilicate were used as materials for distillation and cracking of a petroleum sample with oAPI = 17.4. The process was evaluated by thermogravimetry, in the temperature range from 25 to 900 °C, in a nitrogen atmosphere. The determination of activation energies (Ea) as a function of the degree of conversion was obtained by using the Ozawa–Flynn–Wall kinetic model and at heating rates of 5, 10 and 20 °C min−1. It was observed that the catalytic cracking of the oil presented Ea of 196 kJ mol−1 for 90% conversion. At the same conversion, for the oil containing 10% of Si-MBB catalyst, the Ea decreased to 170 kJ mol−1 and for AlSi-BMM, the Ea was 155 kJ mol−1, showing the efficiency of bimodal materials containing mesopores and macropores in its structure for processing of heavy oil.

Catalysts of AlMCM-48 with different Si/Al molar rations were synthesized by modified hydrothermal method with respect to previous works. As a consequence, the materials showed different porous structures making them of high adsorption capacities and high efficiency to high-density polyethylene (HDPE). Samples synthesized with various Si/Al molar ratios were characterized by X-ray diffraction (XRD), nitrogen adsorption at – 196 °C, scanning electron microscope (SEM), transmission electron microscope (TEM), Fourier transform infrared (FTIR) and dispersive energy X-ray spectrometry (EDX). Characterization results suggested the presence of tetrahedral Al species on AlMCM-48(x), giving highly ordered materials that exhibit thermal stability. It is important to highlight that the use pseudoboehmite as a promising Al source for the synthesis of this type of molecular sieves, leading to materials with slight morphological differences due to the formation of interconnected particles spherical. The catalytic performance showed that the high-density polyethylene (HDPE) degradation reaction occurs in complex reaction steps in the heating rates 5, 10 and 20 °C min−1. The pore diameters of the catalysts influence the degradation process under non-isothermal condition. Furthermore, on the conditions studied, the AlMCM-48(x) catalysts exhibited high conversion values and play important roles in the decrease of HDPE degradation temperature, potentially leading to an efficient process in terms of energy expenditure.

O lixo plástico sofreu um aumento drástico e se tornou um dos maiores problemas ambientais do século XXI. A degradação térmica e catalítica de plásticos é uma das soluções viáveis para esse problema, pois pode conduzir tanto a benefícios de proteção ambiental, quanto para processos economicamente vantajosos em termos de gastos de energia. Neste trabalho, é apresentado um estudo termogravimétrico da conversão do polipropileno (PP) na presença de catalisadores mesoporosos AlMCM-48 (Si/Al=50 e 100). O desempenho catalítico mostrou que a reação de degradação do PP ocorreu em etapas de reações complexas nas taxas de aquecimento 5, 10 e 20 °C min-1. Além disso, o volume dos poros dos catalisadores nas diferentes razões molares Si/Al influenciou o processo de degradação em condições não isotérmicas e desempenhou um papel importante na diminuição da temperatura de degradação do PP. A energia de ativação aparente (Ea) foi determinada pelo método de isoconversão de Vyazovkin. Os parâmetros cinéticos obtidos revelaram uma redução na Ea evidenciando uma média de 89, 66 e 59 kJ mol-1 para a degradação do PP puro, PP + AlMCM-48(50) e PP + AlMCM-48(100), respectivamente. Como mostrado pelos valores médios, ficou evidenciado que a maior eficiência foi do AlMCM-48(100) que teve uma diminuição da energia de ativação de cerca de 30 kJ mol-1 em relação a energia de ativação do PP puro.

Coprocessing of Eucalyptus woodchips (EU) and low-density polyethylene (LDPE) has been investigated using two HBeta zeolites as catalyst. The reactions were carried out in a two-step (thermal/catalytic) system, varying the catalyst to feed (C/F) ratio. A maximum in the yield of the liquid organic fraction (oil*) was observed for both HBeta samples at intermediate C/F ratios due to the occurrence of sequential cracking reactions, which were accompanied by a significant reduction of the oil* oxygen content. This finding, together with the results obtained when feeding pure EU and LDPE, denotes that remarkable synergistic effects occur during the coprocesssing of lignocelllulosic biomass and polyolefinic plastics over HBeta zeolite, mainly by Diels–Alder condensation between furans and light olefins. The presence of acid sites with moderate strength in the HBeta samples is an essential factor to obtain high oil* yields since it limits the extension of severe cracking reactions.

Sodium and activated vermiculites were applied as catalysts in the pyrolysis of glycerol. The physical–chemical characterization showed that acid treatment significantly modified the chemical composition, specific area, porosity and structure of sodium vermiculite. Thermogravimetric analysis of the pyrolysis process showed that the presence of catalysts reduced the degradation temperature of glycerol. Kinetic study by the Ozawa–Flynn–Wall model indicated a reduction in the activation energy (Ea) of the process with the use of the catalysts: thermal pyrolysis, Ea = 106.7 kJ mol−1; thermocatalytic pyrolysis with sodium vermiculite, Ea = 90.7 kJ mol−1; and with activated vermiculite, Ea = 85.2 kJ mol−1. Pyrolysis via a pyrolyzer coupled to gas chromatography/mass spectrometry (Py-GC/MS) showed that activated vermiculite provided higher deoxygenation. Thus, the use of activated vermiculite in thermocatalytic pyrolysis is a good option for the transformation of glycerol, because it decreases the activation energy of the process and increases the selectivity for a range of industrially valued products, such as acetaldehyde, acrolein, acetol, glycidol, propylene glycol and 2-propanol.

This work proposes the conversion of glycerol into higher added value products through its pyrolysis in the presence of the catalyst [Ni(L1)]SBA-15. The catalyst, an SBA-15 silica, was anchored with Schiff base complex [Ni(L1)], L1 being a Schiff Base with diethylenetriamine. The materials were characterized by the techniques of X-ray diffraction, Fourier transform infrared (FTIR) spectromicroscopy, UV–vis absorption spectroscopy, Raman spectroscopy, N2 physisorption, and thermal analysis (TGA/DTG/DSC). The kinetic study of the thermal and thermal/catalytic pyrolysis of glycerol using the iso-conversional methods proposed by KSA (Kissinger-Akahira-Sunose) and FWO (Flynn-Wall-Ozawa). The results show a reduction of activation energy in the presence of [Ni(L1)] SBA-15 compared to SBA-15 and glycerol. The products of the pyrolysis of glycerol were produced and identified by a pyrolyzer coupled to GC/MS and TGA-FTIR. The presence of the catalyst reduced the temperature of the process and resulted in the production of a greater quantity and variety of chemical products of higher added value. This leads to the conclusion that the material has catalytic activity for the thermal degradation of glycerol. The main products obtained from the pyrolysis of glycerol were carbon dioxide, aldehyde, ketone and alcohol.

Thermogravimetry was used in order to evaluate thermal and catalytic degradation of atmospheric residue of petroleum (ATR) which is found at Brazilian refineries, after a process of atmospheric distillation. The catalyst used for the thermocatalytic degradation of ATR was the AlMCM-41 mesoporous material. The AlMCM-41 was obtained from hydrothermal method using cetyltrimethylammonium as organic template. The calcined material was characterized by chemical analysis and X-ray diffraction. The thermogravimetry analysis was carried out at temperature range of 30 to 900 °C and heating rates of 5, 10 and 20 °C min−1, under nitrogen gas. From TG, the activation energy, determined using the Ozawa–Flynn–Wall kinetic method, decreased from 288 kJ mol−1, for pure ATR, to 55 kJ mol−1, in the presence of the AlMCM-41 material, evidencing the efficiency of the mesoporous materials for the catalytic degradation of petroleum residues.

The oil sludge residue presents an aggregate of hydrocarbons, organic and inorganic impurities, and water. The microporous and mesoporous zeolites are considered promising catalysts for processing of petroleum residues generated in refining processes. The aim of this work was to study the degradation of petroleum sludge obtained from primary processing, with applications of an improved thermogravimetry system and HY zeolite, at specific temperature ranges and degradation times, in order to obtain light gases and distillate fuels. The NaY zeolite was synthesized under hydrothermal treatment of a gel containing sodium silicate, sodium aluminate, and water. The obtained solid material was filtered, dried and calcined, and then ion-exchanged with ammonium chloride and calcined in order to obtain its protonic acid form (HY). The samples’ characterization by TG/DTG, XRD, and SEM proved that the crystalline structure of the faujasite zeolite was obtained. The thermal and catalytic degradation of the petroleum sludge was performed with 1.0 g of sample containing 10% of HY zeolite in the temperatures of 100, 200, 300, 400, and 500 °C, varying the time from 0 to 60 min to each temperature, using an oven with temperature program system, adapted with a Shimadzu precision balance. The curves obtained with this system evidenced that the presence of HY zeolite improves the degradation of the residue, with decreasing of the activation energy for the processes, as determined using the Arrhenius model.

Diesel fuel mixtures with high concentrations of biodiesel have been investigated to analyze the technical feasibility of their use in diesel cycle engines regarding thermal and oxidative properties. The results of combined techniques of oxidative stability, high Pressurized Differential Scanning Calorimetry (P-DSC), Calculated Cetane Index (CCI), and calorific power were used to verify the effect of the thermal-oxidative stability as a function of the percentage of biodiesel in the mixtures. The obtained results evidenced that the thermal and oxidative stability decreased with the addition of biodiesel from 50 to 5% v/v. Low stability fuels require rapid use as the oxidation compounds degrade the product and impair vehicle performance, as well as lead to corrosion and clogging problems in various mechanical systems.

Natural gas (NG) production in Brazil has shown a significant increase in recent years. Oil and natural gas exploration and refining activities indicate circa 86% carbon dioxide content in NG, representing a serious problem for environmental issues related to greenhouse gas emissions and increases in global warming. New technologies using CO2 capture materials have been shown to be more efficient than conventional processes. In this work, a bimodal meso&ndash, macroporous silica adsorbent for CO2 adsorption in NG was synthesized and evaluated as a promising material for use in natural gas treatment systems, as silica has specific textural properties that facilitate the capture and storage of this gas. The adsorbent was obtained from silica via the hydrothermal method with n-dodecane emulsion and characterized by X-ray diffraction, scanning electron microscopy, infrared spectroscopy, and the BET specific surface area. Adsorption capacity tests were performed for CO2, methane, and their mixtures by the gravimetric method, demonstrating that the adsorbent was selective for CO2 and obtained a good adsorption capacity. The experimental values obtained were compared and adjusted to the models of Langmuir and Freundlich. Thus, the bimodal silica adsorbent developed in this research proved to be excellent for CO2 adsorption and is a promising material for the treatment of NG.

Concretes were prepared containing oil sludge additive to produce new materials for construction. The oil sludge and concrete have previously been characterized in terms of chemical composition of the elements present in the materials. The concrete blocks were produced with a defined amount of oily sludge of 3.0 mass% on cement/water factor. All samples were cured at room temperature and then heated at 200 °C for 3 hours and 292 °C for 2h. The surfaces of the samples were subjected to previously grinding for the compressive strength testing. These tests were conducted in a press of 2000 kN load capacity. It was found that concrete containing additive showed a positive response in all the compressive strength tests, compared to concrete without the additive

The catalytic cracking of isopropylbenzene was investigaded over hybrid ZSM-12/MCM-41 and HZSM-12/MCM-48 micro-mesoporous materials, in order to verify the effect of the acid site of the accessibil...

In this manuscript, MCM-41 and Co-MCM-41 were synthesized to evaluate the effect of the metal incorporated in the structure of the mesoporous material used in the benzene removal in aqueous medium containing hydrogen peroxide (H 2 O 2 ). The decomposition of H 2 O 2 in the medium containing MCM-41 and Co-MCM-41 was investigated. The techniques used to characterize these materials showed satisfactory results, proving that the synthesis was effective. The decomposition of hydrogen peroxide carried out in the ultraviolet/visible molecular absorption spectrophotometer revealed that the pH of the medium and the presence of cobalt influence its decomposition. In the reaction containing benzene + Co-MCM-41 + H 2 O 2 , it was possible to confirm this information, because there was practically no decomposition at pH = 1.5, 3.0 and 5.0, whereas decomposition was considerable at pH = 7.0 and 10.0 and all H 2 O 2 was decomposed at pH = 12. Tests containing benzene + H 2 O 2 + MCM-41 resulted in a higher removal of analytes in an alkaline medium. The last catalytic tests contained benzene + Co(II) + H 2 O 2 in the aqueous reaction medium; compared to benzene + Co-MCM-41 + H 2 O 2 , it was found that the influence of Co-MCM-41 can be better viewed in pH = 10.0 and 12.0, because 82.1% of benzene was removed after 5 h.

This work presents a study of the reactive distillation of atmospheric petroleum residue (ATR) containing 10% in mass of HY or HZSM-5 zeolites. The process aims the upgrade of ATR in order ...

The hydrothermal synthesis of aluminophosphate molecular sieve type AlPO4-11 was processed from chemicals containing psueudobohemite, 85% phosphoric acid, water, and di-isopropylamine as templating agent. The crystallization of the samples was studied by taking samples in times from 2 to 74 h. The obtained white powder products were characterized by X-ray diffraction patterns (XRD), Fourier transform infrared spectroscopy (FT-IR), thermogravimetry (TG) and differential scanning calorimetry (DTG) data and pH measurement of the mother liquor. The pore volume, as determined from TG and DTG curves, was ca. 0.17 cm3g−1. The percent relative crystallinity was determined by XRD and FT-IR methods. The crystallization kinetics evidenced that the hydrothermal synthesis of AlPO4-11 exhibited in its initial phase a behavior of first order reaction with a specific velocity constant of ca. 0.25 h−1, as determined from XRD and FT-IR data. The results obtained by both X-ray diffraction and infrared spectroscopy are comparable, and FT-IR is found to be a rapid method for estimating crystallinity and structure of aluminophosphate.

In research for materials that can be applied in processing heavy oil (petroleum), this work proposes to synthesize mesoporous heterogeneous catalysts, type SBA-15, with the addition of cerium metal and aluminum. These catalysts were characterized by X-ray diffraction, scanning electron micrographs coupled to energy dispersive spectrometry, spectroscopy in the infrared region by Fourier transform, N2 adsorption and desorption and thermal analysis-thermogravimetry. Thermal tests were performed to evaluate the thermal and catalytic degradation process with a sample of heavy oil (°API = 14). Through the non-isothermal kinetic model of Ozawa Flynn Wall (OFW) some parameters for determining the apparent activation energy of decomposition were obtained. The petroleum with 12% of Ce5Al50SBA-15 showed a catalytic activity for this material. It has been seen that there was a decrease in the Ea in model free of the order from 89.0 to 104.9 kJ mol−1 in α = 50% ± 10%, and it was repeated from the first percen...

In the current work, the incorporation of niobium onto the nanostructured MCM-41 material was studied. The syntheses were carried out by the hydrothermal method using cetyltrimethylammonium bromide (CTMABr) as structural template, sodium silicate and water as solvent. Niobium was introduced in the reactive medium in the form of ammonium niobium oxalate, for obtaining Nb-MCM-41 materials. In order to verify the influence of the niobium content on the properties of the material, the samples were synthesized at Si/Nb molar ratios of 15, 30, 45 and 60. The materials were calcined and characterized by BET surface area, X-ray diffraction, Fourier transform infrared spectroscopy, X-rays fluorescence, for the determination of chemical composition, and scanning electron microscopy. The acidity properties of the MCM-41 and Nb-MCM-41, as determined by n-butylamine adsorption, were investigated by thermogravimetry in the temperature range of room temperature up to 600 °C, under nitrogen gas. From TG/DTG data, the acidity values were of 3.1–3.3 mmol g−1, for materials with Si/Nb molar ratio of 60, 45 and 30. The lower value of acidity of 0.6 mmol g−1, observed for Si/Nb = 15, suggests that at this molar ratio, Nb is not incorporated in the MCM-41 structure.

The co-processing of petroleum and polyethylene terephthalate (PET) was carried out in the presence and absence of a catalyst in an open vessel batch reactor at temperatures of 200, 300, 400, and 500 °C, which corresponds to temperatures of distillation and cracking. The catalyst used was the acidic HY zeolite, which is widely used in petroleum refining. The catalytic co-processing was carried out with the PET–oil charge, at a mass ratio of 1:1, containing 10% of HY zeolite. The conversion degree was measured by knowing the initial sample mass and amount of degraded material for each temperature and reaction time, using an improved gravimetric method consisting of a precision balance and an oven with a heating rate controller. The conversion values obtained were compared for petroleum and PET samples with and without the zeolite catalyst. At temperatures of 200 and 300 °C, the PET showed low conversions, about 5–10%. However, for the catalytic co-processing of PET–oil/HY at these same temperatures...

The catalytic degradation of high density polyethylene (HDPE) was studied in the presence of HZSM-12 zeolites with different Si/Al ratio, by thermogravimetry and pyrolysis coupled to gas chromatography and mass spectrometry. The NaZSM-12 zeolite was synthesized by the hydrothermal method using methyltriethylammonium chloride as template. The HZSM-5 was obtained by ion exchange of NaZSM-12 with ammonium chloride, drying and subsequent calcination. The materials characterization were carried out by chemical analysis, X-ray diffraction, scanning electron microscopy, BET measurements and acidity by n-butylamine adsorption. The obtained HZSM-12 zeolites were physically mixed with HDPE in the proportion of 50%wt and submitted to thermogravimetric analyses at heating rates of 2.5; 5; 10 and 20 °C min −1 . The addition of HZSM-12 to HDPE produced a decreasing in the temperature of polymer degradation, which was proportional to the zeolite acidity. The activation energy (Ea) for the process was determined from the non-isothermal model-free kinetic model proposed by Vyazovkin. The Ea decreases linearly with the concentration of acid sites on the HZSM-12 materials. From the pyrolysis data, the obtained products were typically light gases (C 2 -C 3 ); liquid petroleum gases (C 4 -C 5 ); and gasoline (C 6 -C 10 ). This results suggest that acid zeolites are excellent materials for obtaining alternative fuels from catalytic recycling of plastics.

The presence of sulfur in diesel causes environmental pollution and corrosion of engines. In order to minimize the consequences of this pollutant, Brazilian laws established the maximum of sulfur content that diesel fuel may contain. To meet these requirements, diesel with a maximum sulfur concentration equal to 10 mg kg−1 (diesel S10) has been widely marketed in the country. The reduction in sulfur leads to changes in the physicochemical properties of the fuel, which are essential for the performance of road vehicles. This work aims to evaluate the reduction in the sulfur content in diesel fuel using thermogravimetry. Samples of diesel types S10, S500 and S1800, corresponding to 10, 500 and 1800 mg kg−1 of sulfur content, respectively, were tested according to ASTM methods for specific gravity, flash point and sulfur content. Then, these fuels were characterized by thermogravimetry from room temperature up to 500 °C, in helium flow, at heating rates of 5, 10 and 20 °C min−1. TG and DTG data showed a typical mass loss at ca. 40–320 °C, due to volatilization or distillation of light and medium hydrocarbons. Based on these data, the kinetic behavior of the samples was analyzed and the activation energies (E a) for decomposition of the samples decreased in the order: S1800 > S500 > S10.

Amino-functionalized SBA-15 was prepared using 1.0 and 2.5% chitosan solutions and a wet impregnation method. The adsorbents were characterized by XRD, TG, DSC, SEM, FTIR and nitrogen adsorption/desorption. The results showed that the insertion of chitosan into the holder did not destroy its typical hexagonal structure, maintaining its morphology and a uniform distribution of pores. The thermal stability of the CS and CS-SBA-2.5 materials was investigated using the Vyazovkin and Ozawa–Flynn–Wall kinetic models. The apparent activation energies (E α) obtained ranged around 161–335 kJ mol−1, and a conversion range of 0.2–0.8, with minimum variations, was observed for the two methods and both samples. However, the results showed that the E α, which is an important factor to future applications in adsorption of CO2, was not significantly altered by the presence of SBA-15.

This study was conducted on thermal pyrolysis and thermal-catalytic pyrolysis using the AlMCM-41 catalyst with a Si/Al ratio of 50, as an alternative process for turning sunflower oil into biofuel. The catalyst was characterized by X ray diffraction (XRD), N 2 adsorption/desorption and total acidity by adsorption of n -butylamine, in which it was confirmed an obtainment of AlMCM-41 with an excellent surface area of 857.7 m 2 g −1 and good total acidity. TG curves were used to determine the calcination temperature (450 °C) and the infrared spectroscopy (FTIR) confirmed a complete removal of the CTMA + . Two liquid fractions were obtained from the thermal and thermal-catalytic pyrolysis of sunflower oil: the first, named bio-oil, is a mixture of hydrocarbons similar to mineral diesel; the second, which was named acid fraction, is composed mainly of high acidity components. It was found by gas chromatography (GC/MS) and infrared spectroscopy (FTIR) that the proportion of acid present in the fraction of bio-oil without catalyst is higher than the proportion of acids in the fraction of bio-oil with catalyst, which indicates that the deoxygenation of the products occurred. Thus, it can be noted that the thermal catalytic sample of the bio-oil features more appropriate results to the diesel range, indicating that the acid sites found in AlMCM-41 catalysts were effective for the oil pyrolysis.

Hierarchical Beta zeolites have been prepared employing two strategies of synthesis for the generation of mesopores with different size distribution. In both cases, the starting gel was subjected to pre-crystallization to induce the formation of protozeolitic nanounits. The first strategy involves the reorganization of the protozeolitic nanounits by incorporation of a surfactant (cetyltrimethylammonium bromide, CTAB), whereas the second one is based on the use of a silanization agent (phenylaminopropyl-trimethoxysilane, PHAPTMS) that it is grafted to the outer part of the nanounits to avoid their total merge during the crystallization process. In addition, conventional Beta zeolite and ordered mesoporous aluminosilicates have been prepared and employed as reference samples. All materials have been characterized by a number of techniques, whereas their catalytic behavior has been evaluated in the cracking of high density polyethylene (HDPE). The h-Beta (CTAB) sample shows a narrower mesopore size distribution, more uniform and stable tetrahedral Al species and a higher acid strength than the material obtained from silanized nanounits, although the latter exhibits a larger accessibility as denoted by its higher mesopore/external surface area (351 m 2 /g in h-Beta (PHAPTMS) versus 228 m 2 /g in h-Beta (CTAB)). While the ordered mesoporous aluminosilicates were almost inactive in HDPE cracking ( 50 wt% of conversion). The results obtained indicate that the overall catalytic activity depends mainly on the accessibility to the active sites, whereas the product selectivity is rather determined by the acid strength of the zeolite catalysts. Thus, h-Beta (CTAB) sample promoted in a great extension both end-chain cracking and aromatization reactions due to its high acid strength.

The reuse and recycling of amine-silica materials as CO2 adsorbents were investigated for understanding their industrial viability. CO2 adsorbents were obtained by grafting of diethylenetriamine (DT) or impregnation of polyethyleneimine (PEI) onto SBA-15 silica. CO2 desorption conditions were evaluated, optimizing the time and temperature to reduce energy costs. In all cases, conditions as mild as 90 °C and 90 min were enough to completely remove all CO2 adsorbed. After that, a number of adsorption-desorption cycles at 110 °C for DT (60 min) and PEI (75 min) samples were carried out in order to study their cyclability. The recycling of CO2 adsorbents after their lifespan was studied by analysing the physicochemical properties and CO2 uptake of recycled samples obtained by calcination and subsequent re-functionalization with DT or PEI. Materials obtained after grafting the calcined samples exhibited progressively thicker silica walls and lower silanol surface concentration, yielding a smaller amine efficiency during CO2 capture. On the contrary, materials obtained after impregnating the calcined samples maintained their CO2 adsorption properties even after 6 cycles, without significant changes in their silica structure or amine efficiency for CO2 adsorption.

The synthesis control in obtaining CeO2 nanostructures is of fundamental importance for obtaining materials with desired properties. However, progress in the synthesis and control of the properties of these unidirectional (1D) nanomaterials remains a major challenge. In this work, alkaline hydrothermal synthesis without the use of a template was performed, under different reaction conditions (NaOH concentration, temperature and time of synthesis), and the influence on the morphological, structural and optical properties of CeO2 nanotubes (CeNTs) formed was discussed. In some cases, hydrated CeNTs, organized in a cubic fluorite structure, were obtained, with varying sizes, and varying quantity of oxygen vacancies, according to the condition of syntheses used, thus generating materials with different properties. It was observed that the external diameter (De) of the obtained nanotubes and oxygen vacancies increased the higher the NaOH concentration, the temperature and the time used in the reaction. Only the synthesis conditions of 5 M NaOH and 150°C do not promote the morphology of interest, with the formation of prisms and a mixture of nanotubes/nanocubes. The best synthesis conditions were obtained when using an alkaline concentration of 10 mol.L−1 at 125 °C for a reaction time of 72 h, since, under these conditions, a higher yield of nanostructures was obtained over an interesting size range (CeNTs with internal and external diameters of 7 and 24,6 nm, respectively). The band gap value of 2.60 eV, which is possibly responsible for the red shifting of band gap, indicates that these materials are photosensitive in the visible region. The mechanism involves the process of cerium salt dissolution and recrystallization of CeO2 nanotubes. This work shows, for the first time, that control of the formation, size and different quantities of Ce4+/Ce3+ of the CeNTs that can be reached by adjusting the synthesis parameters. Control in obtaining these nanostructures, combined with a narrow gap energy, it may show a differential performance for applications in the photocatalysis, sensors, nanomedicine and advanced electronic devices areas.

The aim of this work was to evaluate the influence of the purification process on the stability of Jatropha curcas biodiesel. The biodiesel was obtained using a variety of purification processes: three wet methods with different drying processes (vacuum oven, conventional oven and anhydrous sodium sulfate) and one dry method (purification with adsorbent magnesium silicate). Biodiesel was characterized through the analysis of carbon residue, acidity index, infrared and gas chromatography. The composition J. curcas oil indicated 56.3 % of unsaturated fatty acids and 43.7 % of saturated fatty acids. Jatropha oil presented high quantity of saturated acids, which are less susceptible at oxidation. The biodiesel sample that was chemically purified (PUsq) presented better purity, indicating be the process more efficient in remove the residues of synthesis. Thermogravimetric curves of purified biodiesel by wet method, PUsq, with chemical drying using anhydrous sodium sulfate, and PUsv, with vacuum drying, showed the highest initial decomposition temperatures, indicating higher thermal stability. The carbon residue and infrared analyses suggested that contamination by catalyst residue is a determining factor in reduction of the oxidative stability of biodiesel. The oxidative stability was evaluated using Rancimat and pressure differential scanning calorimetry. Biodiesel samples showing better oxidative stability were purified using PUsq and PUsv, which obtained stability of 6 h using the Rancimat technique, the minimum limit set by Brazilian legislation, without the addition of antioxidant, suggesting that these methods least influenced the stability of biodiesel.

Mg/Al layered double hydroxides (LDH) containing KI were synthesized and tested as basic heterogeneous catalysts for transesterification of sunflower oil, in order to obtain biodiesel. The process was carried out using reflux with 15:1 molar ratio of methanol to sunflower oil, and catalyst concentration of 2 mass%. The characterization of sunflower oil and biodiesel was accomplished according to ASTM and EN standard methods. The gas chromatographic and TG/DTG profiles were evaluated, and the results of yield and conversions were compared. The gas chromatographic analysis showed that the catalysts were effective in converting vegetable oil into biodiesel, specially using LDH catalysts modified with KI and molar ratio Mg/Al = 1, with conversions higher than 99 % indicating the strong influence of the chemical composition and controlled basicity, due to the presence of potassium in the structure of the catalyst.

Alumina-supported potassium oxides are promising catalysts for the transesterification reaction of vegetable oils for biodiesel production. Various potassium compounds Al2O3-supported were prepared via impregnation method. Potassium oxide (K2O) is a good candidate for a solid base catalyst from an economical point of view. In the present work, we reviewed K2O catalyst for the vegetable oil transesterification based on a variety of related research papers. The potassium compounds supported in catalysts, KOH/Al2O3, KNO3/Al2O3, KI/Al2O3, KF/Al2O3 and K2CO3/Al2O3, were optimized through various reaction parameters, such as: amount of catalyst, molar ratio of oil to alcohol, reaction time and temperature. Yields and conversions from various catalytic systems applied for biodiesel production were also compared. Among the catalysts studied, the KF/Al2O3 showed higher catalytic activity and a small amount of catalyst requirement in the transesterification reaction, indicating that it can be applied as a potential catalyst in the industry.

The AlSBA-15 nanomaterials with different Si/Al ratios were investigated as a promising material for processing of atmospheric residue of petroleum (ATR). The processing was performed in a thermobalance using nitrogen as a carrier gas at different heating hates. The catalytic pyrolysis was performed with ATR sample containing 20% mass of AlSBA-15. Based on TG data by applying Ozawa-Flynn-Wall kinetic model, the activation energy for the pyrolysis of ATR was higher than for the ATR/AlSBA-15, throughout all range of decomposition, indicating that the nanostructured material is a promising material for processing petroleum residues in order to obtain liquid products in the gasoline and diesel range.

The zeolite HZSM-5, was synthesized in the absence of an organic template. The characterization of zeolite HZSM-5 was performed by X-ray diffraction, N2 adsorption/desorption isotherms and scanning electron microscopy. For catalytic tests, applying the free kinetic model, it was observed that the activation energy for the pyrolysis of pure VGO was of 82 kJ mol−1 and for VGO/HZSM-5, the value decreased to approximately 60 kJ mol−1, demonstrating the effectiveness of the acid sites effect of zeolite ZSM-5 for the VGO pyrolysis resulting in production of gas, gasoline and diesel.

The catalytic cracking of low density polyethylene (LDPE) was accomplished using nanocrystalline HZSM-5 zeolites. Nanocrystalline ZSM-5 zeolites were synthesized by a seed-assisted method from an organic-template-free system employing three different seeding strategies: two of these strategies based on aqueous clear solutions containing the ZSM-5 precursors (silanized and non-silanized) and the third strategy based on a commercial ZSM-5 zeolite in powder form. The plastic cracking reactions were carried out at 380–420 °C, employing really mild conditions (plastic to catalyst mass ratio of 100). Nanocrystalline HZSM-5 zeolites prepared by seed-induced synthesis based on liquid solutions exhibit a superior catalytic activity than the reference microcrystalline zeolite. Conversion values very close to 100% are achieved at 420 °C, by using these catalysts, while significant conversion values (>50%) are still attained at 380 °C. Moreover, these nanocrystalline HZSM-5 zeolites promote the production of a high proportion of light olefins (>60% at 380 °C), propylene, 1-butene, isobutene, being the main products (∼50%). Nanocrystalline HZSM-5 synthesized from a clear solution containing an organic structure-directing agent (TPA + ) exhibits a 100% conversion value at 380 °C. However, the economic and environmental advantages of the seed-assisted synthesis from a TPA + free system and the remarkable activity showed by the nanocrystalline zeolites obtained, makes of these materials interesting catalysts in the LDPE catalytic cracking.

Resumo O polietileno de baixa densidade (PEBD) é um dos polímeros mais usados atualmente, e a grande quantidade desse polímero produzida resulta em toneladas de resíduos, que necessitam ser tratados. Neste trabalho foi realizada a pirólise termocatalítica do PEBD usando como catalisador a argila vermiculita modificada, como alternativa para o tratamento dos resíduos. A argila foi tratada com solução de ácido nítrico a diferentes concentrações e calcinada a 400 °C. Os materiais foram caracterizados por técnicas de difratometria de raios X, termogravimetria, adsorção de nitrogênio e espectroscopia de energia dispersiva. A pirólise térmica e termocatalítica foi realizada em um micro reator acoplado com GC/MS, a 500 °C. O intuito da pirólise de resíduos poliméricos é a obtenção de hidrocarbonetos leves (C

A single-surfactant templating method was explored for the synthesis of mesoporous zeolites under microwave irradiation, which allowed programming of temperature and time over a wide range of conditions and resulted in a significant reduction of the synthesis time. Most importantly, this approach eliminated the use of an organic molecular template for creating microporous zeolitic structure. Two preparation methods were examined: one-pot and two-step synthesis routes. The synthesized materials were shown to be micro-mesoporous structures consisting of zeolitic crystallites (ZSM-5/Mordenite-type) embedded into amorphous domains of hexagonally ordered mesoporous silica, MCM-41, with properties comparable with those reported for the samples obtained by dual templating and autoclave heating. Mesopores were created by soft-templating, whereas the crystalline microporous framework was formed in the absence of organic molecular template under microwave irradiation. One of the samples was tested as a catalyst in the cracking of vacuum gas oil, which resulted in obtaining hydrocarbons in the range of liquefied petroleum gas, gasoline and diesel, indicating that the mesoporous zeolitic materials prepared via single-surfactant templating under microwave irradiation are effective catalysts for the pyrolysis of vacuum gas oil. Both the synthesis procedure and the presented application of mesoporous zeolites address a few aspects of green chemistry and sustainability.