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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.

This study investigates the use of CaO–TiO2 mixed oxides as solid base catalysts to produce biodiesel from cotton oil (Gossypium hirsutism). These CaO–TiO2 mixed-oxide catalysts were prepared in different molar proportions of Ca:Ti (0.75Ca:0.25Ti, 1Ca:1Ti e 0.25Ca:0.75Ti) and characterized by X-ray diffraction, Fourier transform infrared spectroscopy (FTIR), thermogravimetry (TGA), Raman spectroscopy, scanning electron microscopy (SEM) coupled with energy-dispersive X-ray analysis, and Brunauer–Emmett–Teller surface area analysis. The effects of reaction parameters such as the methanol/oil molar ratio, the amount of catalyst amount, and the reaction temperature were also investigated. The process was evaluated by TGA and confirmed by FTIR and GC/MS. The catalysts obtained were tested in the following reaction parameters: 20:1 methanol:oil molar ratio; 10% of catalyst amount; and 60 °C temperature for 5 h. The best catalyst was determined to be 0.25Ca–0.75Ti (calcined at 800 °C), considering its catalytic and anti-leeching abilities, because it obtained the highest yield (92.2%) without leaching calcium. Therefore, CaO–TiO2 catalysts have the potential to be used in biodiesel products.

The search for a drop-in fuel obtained from residual biomass or oilseed that does not compete with food, as Pachira aquatica Aubl. oil has been imputing the research. This work focused on the characterization and application of the support (KIT-6) catalyst (Mo/KIT-6) in pyrolysis of the waste frying and P. Aquatica Aubl. oil through a kinetic study by thermogravimetry (TGA/DTG) technique and thermogravimetry coupled with Fourier-transform infrared spectrophotometer (TGA-FTIR). The supports and catalysts were characterized by different techniques such as X-ray diffraction, thermal analysis (TGA/DTG), adsorption and desorption of N2 and scanning electron microscopy coupled with energy-dispersive X-ray analysis (EDS). The support and catalyst presented good structural organization and textured properties, showing that the structuring of KIT-6 was achieved and that in the impregnated form, Mo/KIT-6 presented the Mo dispersion by the surface of the support. Kinetic study pyrolysis of oils was performed using the iso-conversional method proposed by Kissinger–Akahira–Sunose which was applied to determine the activation energy (Ea) of without (thermal pyrolysis) and with the catalyst (thermal/catalytic pyrolysis) in the study. The presence of catalysts on volatilization/pyrolysis of oils showed no significant reduction in activation energy (

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.

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.

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 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.

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.

This study aimed to evaluate the activity of Al-MCM-41, as mesoporous heterogeneous catalyst, for the thermal and catalytic degradation of a Brazilian heavy crude oil (14°API), via thermogravimetry. The American Petroleum Institute gravity (°API) is a measure of how light of heavy petroleum is when compared to water. The API value is an inverse measure of the relative density of a petroleum liquid, and it is used to compare the relative densities of petroleum samples. The catalytic activity was investigated as a function of different concentration of Al-MCM-41 (1, 3, 5, 10 and 20 mass%) added to the oil, as well as the apparent activation energy relative to degradation process. The TG runs were carried out at temperature range of 30–900 °C, at heating rates of 5, 10 and 20 °C min−1, under nitrogen atmosphere. From TG/DTG tests, the material presented effective catalytic activity when added to the heavy oil at concentration higher than 5 mass%. This property was clearly evidenced by the activation energy values. By the application of Ozawa–Flynn–Wall kinetic model, it was observed that when the amount of catalyst was increased, the value of the apparent activation energy decreased from 103 kJ mol−1 (without catalyst) to 70 kJ mol−1 (with 20 mass% of catalyst).

Biofuel production is acquiring an important role as an energy alternative. Several research groups have proposed the use of heterogeneous catalysts in order to replace homogeneous catalysts. A new group of basic catalysts has been prepared with the aim of being used as heterogeneous catalysts in biodiesel production. The catalysts KNO3/Al2O3 have been characterized and evaluated in the transesterification processes. They were characterized by X-ray diffraction and Scanning electron micrographs. The catalytic activity was evaluated in the transesterification of sunflower oil in biodiesel. The thermal stability of the biodiesel and the percentage of esters were evaluated. Through the TG curves, the samples of 2 and 4 % of KNO3/Al2O3 have presented two mass loss and partial conversion of triglycerides in esters. Thus, the sample that contains 4 % KNO3/Al2O3 has shown better catalytic activity in the transesterification reaction of sunflower oil, with a conversion rate of 60 % ethyl esters. On the other hand, the samples of 6 and 8 % of KNO3/Al2O3 have revealed only mass loss.

This work investigated the synthesis of biodiesel from palm oil, its thermal stability using the Ozawa–Flynn–Wall and Vyazovkin kinetic models and its thermoxidation using thermogravimetry. The obtained biodiesel was in accordance with the specifications of Resolution No. 7/2008 of the ANP. The 97.4% wt conversion of palm oil to methyl esters confirmed the efficiency of the conversion of fatty acids into esters. The thermal analysis was performed on a thermobalance using heating rates of 5, 10 and 20 °C min−1. The oil exhibited two mass losses, and the biodiesel exhibited only one mass loss. The average values of the obtained apparent activation energies were 184.6 and 191.3 kJ mol−1 for palm oil and 64.1 and 65.3 kJ mol−1 for biodiesel. Additionally, the results indicate that thermal analysis can be used as a tool for monitoring the thermoxidation of biodiesel as a function of time.

The mesoporous material AlSBA-15 with Si/Al molar ratio of 25 was synthesized by the hydrothermal method and characterized by X-ray diffraction and nitrogen adsorption. This is a promising material in the field of catalysis, particularly for petroleum refining, since their mesopores facilitate the accessibility of large hydrocarbon molecules to the active sites of AlSBA-15, producing light hydrocarbons. In order to evaluating the catalytic activity of AlSBA-15, a sample of ca. 10 % in mass of this solid was physically mixed with atmospheric residue of petroleum (ATR) and heated in a thermobalance from room temperature up to 900 °C, under nitrogen atmosphere. From TG curves, it was observed a reduction in the onset temperature, when AlSBA-15 was used as catalyst for the degradation process of ATR. The kinetic model proposed by Ozawa–Flynn–Wall yielded some kinetic parameters to determine the apparent activation energy of the degradation, evidencing the efficiency of the mesoporous material, since there was a decrease in the activation energy for the catalytic degradation. The ATR alone and mixed with AlSBA-15 was also heated in a pyrolysis reactor coupled to a gas chromatograph and mass spectrometer (Py-GC/MS). From the chromatograms, it was observed an increase in the yield of hydrocarbons in the range of gasoline and diesel derived from the catalytic process. These results are due to the combination of the mesoporosity and acidity of the AlSBA-15 for application in the process of pyrolysis of hydrocarbons molecules constituents of the ATR.

The oxidation of oils and biodiesels occurs due to several factors: the quantity of double bonds and the presence of allylic and bis-allylic hydrogens. Esters (biodiesel) that have large amounts of unsaturated fatty acids are more susceptible to oxidation than saturated. The aim of this work was to analyze the thermal and oxidative stability of ethyl biodiesel from Jatropha curcas L. and beef tallow by thermogravimetric, pressure differential scanning calorimetry, and PetroOxy methods. The samples of biodiesel from beef tallow present higher oxidation stability compared to biodiesel from J. curcas. In relation to calorimetric curves of biodiesel from J. curcas and beef tallow stored by 60 days without and with antioxidant, there was verified displacement of peak temperature of the transition to higher temperatures, respectively. Just a sample of biodiesel from beef tallow stored for 60 days with 3,000 ppm of antioxidant t-butyl-hydroxyquinone was within the standard established by Brazilian National Agency of Petroleum, Natural Gas, and Biofuels (ANP). The biodiesel from beef tallow was more stable in terms of thermal and oxidative stability than biodiesel from J. curcas. The thermal and oxidative stability of biodiesel depends on its chemical structure; this corroborates the fact that the oils with a predominance of saturated fatty acids are more stable than the unsaturated.

The diversity of raw materials and technological routes employed in the biodiesel production has resulted in products with different chemical properties. This non-uniformity in the biodiesel composition may influence to the fuel quality. The aim of this study was to evaluate biodiesel blends of passion fruit and castor oil in different proportions and their thermal stability. Biodiesel blends of passion fruit and castor oil presented parameters in the standards of the Petroleum, Natural Gas and Biofuels National Agency. The TG curves indicated that castor oil biodiesel was more stable. Passion fruit biodiesel has a high content of oleic and linoleic acids, which are more susceptible to oxidation. Biodiesel blend of passion fruit and castor oil 1:1 increased the thermal stability in relation to passion fruit biodiesel. Biodiesel blend of passion fruit and castor oil 1:2 presented higher thermal stability, because castor oil has a high content of ricinoleic acid.

Thermogravimetry was applied in order to investigate the catalytic degradation of heavy oil (15.4oAPI) over silica-based MCM-41 mesoporous molecular sieve. This material was synthesised by the hydrothermal method, using cetyltrimethylammonium bromide as organic template. The physicochemical characterization by nitrogen adsorption, X-ray diffraction, and thermogravimetry, showed that the obtained material presents well-defined structure, with a uniform hexagonal arrangement. The thermal and catalytic degradation of heavy oil was performed by thermogravimetric measurements, in the temperature range from 30 to 900 °C, at heating rates of 5, 10, and 20 °C min−1. By using the model-free kinetics, proposed by Vyazovkin, it was determined that the activation energy to degrade the heavy oil was ca. 128 kJ mol−1, and for degradation of oil in presence of MCM-41, this value decreased to 69 kJ mol−1, indicating the performance of the mesoporores catalyst for the degradation process.

The capture of carbon dioxide was carried out using MCM-41 and SBA-15 as adsorbents. These mesoporous materials were synthesized by the hydrothermal method, and subsequently functionalized with the di-iso-propylamine (DIPA). Then, they were characterized by XRD, BET, and TG/DTG. The X-ray diffraction patterns of the synthesized samples showed the characteristic peaks of MCM-41 and SBA-15, indicating that the structures of these materials were obtained. The functionalized samples presented a decrease of the intensities of these peaks, suggesting a decreasing in the structural organization of the material; however, the mesoporous structure was preserved. For the adsorption capacity measurements, the materials were previously saturated with carbon dioxide at 75 °C, and then desorbed in a thermobalance in the temperature range of 25–900 °C, under helium atmosphere. Desorption tests showed that the functionalized MCM-41 presented a weight loss of 7.5 wt%, against 5.9 wt% for SBA-15. The obtained values indicate that these nanostructured materials can be used as adsorbent for carbon dioxide capture.

Thermogravimetry (TG) was used in this study to evaluate thermal and catalytic pyrolysis of Atmospheric Petroleum Residue (ATR) which can be found in the state of Rio Grande do Norte/Brazil, after a process of atmospheric distillation of petroleum. The utilized sample in the process of catalytic pyrolysis was Al-MCM-41, a mesoporous material. The procedures for obtaining the thermogravimetric curves were performed in a thermobalance with heating rates of 5, 10, and 20 °C min−1. From TG, the activation energy was determined using the Flynn–Wall kinetic method, which decreased from 161 kJ mol−1, for the pure ATR, to 71 kJ mol−1, in the presence of the Al-MCM-41, showing the efficiency of the catalyst in the pyrolysis of Atmospheric Petroleum Residue.

The nanostructured hybrid AlMCM-41/ZSM-5 composite was synthesized starting from a hydrogel with molar composition SiO2:0.32Na2O:0.03Al2O3:0.20TPABr:0.16CTMABr:55H2O. The cetyltrimethylammonium bromide (CTMABr) and tetrapropylammonium bromide (TPABr) were used as templates. The above mentioned material presents morphological properties with specific characteristics, such as the surface area of the composite which is approximately half of the surface area of the conventional MCM-41. Another interesting feature is the formation of walls with the double of the density of the MCM-41 structure, which characterizes the hybrid material, resulting in a high stability material for catalytic application. The aim of this study is obtain optimized structures of the hybrid material and for this purpose variations in the synthesis time were carried out. A comparative analysis was performed including X-ray diffraction, Fourier transform infrared spectroscopy, and Thermogravimetry measurements. The model-free kinetic algorithms were applied in order to determinate conversion and apparent activation energy of the decomposition of the CTMA+ and TPA+ species from the hybrid AlMCM-41/ZSM-5.

Degradation of low density polyethylene (LDPE) was studied for the pure polymer and mixed with silicoaluminophosphate SAPO-11 catalyst. SAPO-11 was synthesized by hydrothermal method using di-isoprolpylamine as structure template, and characterized by XRD and SEM. From X-ray diffraction, it was observed that SAPO-11 was obtained with high crystallinity. Using the model-free kinetics, proposed by Vyazovkin, the activation energies were determined for the process of polymer degradation. It was found that the degradation process of 90% of LDPE mixed with SAPO-11 over a period of 1 h, occurred at a temperature of 378 °C, while for the pure LDPE, the temperature was increased to 434 °C in the same period of time and conversion, indicating that SAPO-11 was an effective catalyst for the degradation of LDPE. The activation energy for the degradation of pure LDPE was equivalent to 251 kJ mol−1. Also, when the SAPO-11 was mixed with the polymer, this value was decreased to 243 kJ mol−1.

Model-free kinetic studies for volatilization of Brazilian sunflower oil and its respective biodiesel were carried out. The biodiesel was obtained by the methylic route using potassium hydroxide as catalyst. Both sunflower oil and biodiesel were characterized by physicochemical analyses, gas chromatography, simulated distillation and thermogravimetry. The physicochemical properties indicated that the oil and biodiesel samples are in accordance with the specifications of the Brazilian National Agency of Petroleum, Natural Gas and Biofuels (ANP). Gas chromatography indicated that the biodiesel was obtained with a content of ester of ca. 97.35 wt%. The TG curves indicated that the temperatures for volatilization of biodiesel are lower than for sunflower oil, which is explained by their different compositions and properties. The value of the apparent activation energy for the volatilization process, as determinated by the Vyazovkin Method, was higher for sunflower oil than for biodiesel.

The aim of this work is to determine the acti- vation energy for the thermal decomposition of poly (ethylene terephthalate)—PET, in the presence of a MCM- 41 mesoporous catalyst. This material was synthesized by the hydrothermal method, using cetyltrimethylammonium as template. The PET sample has been submitted to ther- mal degradation alone and in presence of MCM-41 catalyst at a concentration of 25% in mass (MCM-41/PET). The degradation process was evaluated by thermogravimetry, at temperature range from 350 to 500 C, under nitrogen atmosphere, with heating rates of 5, 10 and 25 C min -1 . From TG, the activation energy, determined using the Flynn-Wall kinetic method, decreased from 231 kJ mol -1 , for the pure polymer (PET), to 195 kJ mol -1 , in the pres- ence of the material (MCM-41/PET), showing the catalyst efficiency for the polymer decomposition process.

Biodiesel is susceptible to autoxidation if exposed to air, light and temperature, during its storage. Physic nut (Jatropha curcas L.) seeds show potential application for biodiesel production since its oil yields high quality biodiesel. This work aims to evaluate the thermal behavior of the physic nut oil and biodiesel, from several Brazilian crops, by means of thermoanalytical techniques. Thermogravimetry (TG) and pressurized-differential scanning calorimetry (PDSC) were used in order to determine the applicability of physic nut biodiesel as fuel. Results suggest that physic nut biodiesel is a practical alternative as renewable and biodegradable fuel able to be used in diesel motors.

The degradation kinetics of the ABS terpolymer (acrylonitrile-butadiene-styrene) was investigated by means of thermogravimetric analysis. The samples were heated from 30 to 900°C in nitrogen atmosphere applying three different heating rates: 5, 10 and 20°C min−1. The Vyazovkin model-free kinetic method was used to calculate the activation energy (E) of the degradation process as a function of conversion and temperature. Between 20 and 80% of conversion, E was calculated and the figures were: for ABS GP, E is 204.5±11.5 kJ mol−1 (medium value); for ABS HI, E is 239.0±9.8 kJ mol−1; for ABS HH, E is 242.4±5.4 kJ mol−1.

This work describes the covalent grafting of 3,4,9,10-perylenediimides (PDI), which are fluorescent dyes with very interesting optical properties, onto the walls of mesoporous molecular sieves MCM-41 and SBA-15. The mesoporous materials were first treated with 3-aminopropyltriethoxysilane (APTES) in anhydrous toluene, generating amine-containing surfaces. The amine-containing materials were then reacted with 3,4,9,10-perylenetetracarboxylic dianhydride (PTCA), generating surface-grafted PDI. Infrared spectra of the materials showed that the reaction with amino groups took place at both anhydride ends of the PTCA molecule, resulting in surface attached diimides. No sign of unreacted anhydride groups were found. The new materials, designated as MCMN 2 PDI and SBAN 2 PDI, presented absorption and emission spectra corresponding to weakly coupled PDI chromophores, in contrast to the strongly coupled rings usually found in solid PDI samples. The materials showed a red fluorescence, which could be observed by the naked eye under UV irradiation or with a fluorescence microscope. The PDI-modified mesoporous materials showed electrical conductivity when pressed into a pellet. The results presented here show that the new materials are potentially useful in the design of nanowires.

The biodiesel obtained by transesterification by reaction between ester and an alcohol in the presence of catalyst. The purpose of this work is to evaluate the thermal and kinetic behavior of the methanol biodiesel derived from cotton oil. The quality analysis was done by gas chromatography and proton nuclear magnetic resonance spectrometry (1H NMR) in order to examine if the product meets with the requirements of the European Standard EN 1403. The thermogravimetric profile of the cotton biodiesel indicated that the decomposition steps are associated to the volatilization and/or decomposition of the methyl esters. Kinetic data was also obtained by thermal analysis.

This work describes the encapsulation of N , N ′-bis(2-phosphonoethyl)-3,4,9,10-perylenetetracarboxylic diimide (PPDI), a water-soluble perylene dye, in the channels of mesoporous silica MCM-41. The incorporation of the dye was achieved by stirring MCM-41 with aqueous solutions of PPDI. The solid material obtained by this process exhibited a red fluorescence. Diffuse reflectance and emission spectra of the fluorescent powder suggested a highly organized arrangement with the PPDI molecules self-assembled in a 1D stack inside the channels of the mesoporous silica. The new materials described here have potential applications as nanoscale optoelectronic devices, such as conducting nanowires and fluorescent gas sensors.

Diesel oil has an important role in the field of urban traffic as well as in the transportation of products. However, the amount of the non-renewable sources is continuously decreasing. This fact and the environmental requirements brought the necessity to search for other, renewable sources. This paper aimed the dynamic kinetic calculation of thermal decomposition of castor oil, methanol biodiesel and ethanol biodiesel using Coats–Redfern, Madhusudanan and Ozawa methods. On the base of the thermogravimetric curves the following thermal stability order could be established: castor oil>ethanol biodiesel>methanol biodiesel. Kinetic data presented coherent results. Methanol biodiesel presented lower activation energy than ethanol biodiesel, suggesting that methanol biodiesel has a better quality for combustion.

This work evaluates the thermal and kinetic behaviour of corn biodiesel obtained by the methanol and ethanol routes. As to the TG curves, in air three thermal decomposition steps are for the methanol biodiesel and two steps are for the ethanol biodiesel. These steps are related to the evaporization and/or combustion of the methyl and ethyl esters, respectively. The corn oil presented four thermal decomposition steps in air, and only one step in nitrogen. These steps were attributed to the evaporization and/or decomposition of triglycerides. The TG and DTA profiles of the biodiesel approach the mineral diesel oil ones.

The growing petroleum deficit requires the development of alternative fuel sources. Biodiesel is a good alternative, as it is a biodegradable and renewable product, which obeys the carbon cycle. In this work, the biodiesel from babassu was synthesized using the methanol route, and characterized by physico-chemical analyses in order to make able the investigated biodiesel to fulfill with its properties the requirements of Brazilian National Agency for Petroleum, Natural Gas and Biofuel (ANP). Besides gas chromatography, IR spectroscopy experiments and thermoanalytical measurements in air and in nitrogen were done to determine the main thermal decomposition processes and calorimetric events. The evaporation temperature of babassu biodiesel was similar in both atmospheres, started around 52 in air and around 60°C in nitrogen.

This work presents the characterization and the kinetic compensation effect of corn biodiesel obtained by the methanol and ethanol routes. The biodiesel was characterized by physico-chemical analyses, gas chromatography, nuclear magnetic resonance and thermal analysis. The physico-chemical properties indicated that the biodiesel samples meet the specifications of the Brazilian National Agency of Petroleum, Natural Gas and Biofuels (ANP) standards. The analyses by IR and 1H NMR spectroscopy indicated the ester formation. Gas chromatography indicated that biodiesel was obtained with an ester content above 97%. The kinetic parameters were determined with three different heating rates, and it was observed that both the methanol and ethanol biodiesel obeyed the kinetic compensation effect.

Nanoporous silica with narrow pore size distribution has attracted increasing attention as a novel material for separations and reactions involving large molecules. SBA-15 has been synthesized in an acidic medium using a triblock copolymer as template. In this work, the SBA-15 was synthesized by the hydrothermal treatment at 373 K for 48 h, of a gel with the following overall molar composition: 1.0TEOS:0.017P123:5.7HCl:193H2O, where TEOS is tetraethyl orthosilicate and P123 is poly(ethylene oxide, propylene oxide and 1,4-dioxane). The obtained material was characterized by thermogravimetry, X-ray diffraction, infrared spectroscopy and BET surface area. A kinetic study using the model free model was accomplished in the stage of decomposition of the template (P123). The obtained value of the apparent activation energy was ca. 131 kJ mol–1.

Thermogravimetry (TG) and mass spectrometry (MS) combined techniques have been used to investigate the thermal degradation and catalytic decomposition of high-density polyethylene (HDPE) over solid acid catalysts as H-ZSM-5, Al-MCM-41 and a hybrid material with a bimodal pore size distribution (H-ZSM-5/Al-MCM-41). The silicon/aluminum ratio of all catalysts is 15. Both thermal and catalytic processes showed total conversion in a single mass loss step. Furthermore, the catalytic conversion presents average reduction of 27.4%, in the onset decomposition temperature. The kinetic parameters were calculated using non-isothermal method. These parameters do not indicate significant differences between the thermal and catalytic processes. Even though, the presence of the catalysts changes the reaction mechanism, from phase boundary controlled reaction to random nucleation mechanism. Important difference in distribution of evolved products was detected when several catalysts were used. However, in all cases the main products were alkanes (C2, C3 and C4), alkenes (C3 and C4), dienes (C4 and C5) and traces of aromatic compounds.

The degradation kinetics of polycarbonate with flame retardant additive was investigated by means of thermogravimetric analysis. The samples were heated from 30 to 900C in nitrogen atmosphere, with three different heating rates: 5, 10 and 20C min–1. The Vyazovkin model-free kinetics method was applied to calculate the activation energy (E a) of the degradation process as a function of conversion and temperature. The results indicated that the polycarbonate without flame retardant additive starts to loose mass slightly over 380C and the polycarbonate with flame retardant additive, slightly over 390C (with heating rate of 5C min–1). The activation energy for flame retardant polycarbonate and normal polycarbonate were 190 and 165 kJ mol–1, respectively.

Aspartame (APM) has been a center of discussion due to the toxicity of its metabolism products. This work studied the thermal degradation of aspartame and its products of conversion in a sweetener using isothermal thermogravimetry (TG), infrared (FTIR) and high-performance liquid chromatography (HPLC). The TG curves were performed using a Shimadzu Thermobalance, under air atmosphere, flow rate of 20 mL min−1 and heating rate of 10 °C min−1. The chromatograms were performed using a Shimadzu Chromatograph with diode-array detector at 210 nm, C18 column, water–acetonitrile (90:10) and 0.1% trifluoroacetic acid. The 5-benzyl-3,6-dioxo-2-piperazineacetic acid (5BZ) was identified as only one product of thermal conversion from aspartame (APM). The 5BZ and APM have been identified and quantified through the comparison of areas and retention time established with standards. The chromatograms had presented limits of quantification (LOQ) and detection (LOD) of 5; 2 μg mL−1 and 10; 5 μg mL−1 for 5BZ and APM, respectively. The samples have indicated recovery of 100.42 ± 1.34%. The content of APM in the sweetener was 19.08 mg ± 2.22%, this amount is within specifications (19 mg ± 10%). The standard APM was heated at 80–220 °C in TG-isothermal and chromatograms have indicated the total conversion of APM to 5BZ, which showed a maximum rate of conversion in a temperature range of 140–160 °C. In the sweetener the APM was converted to 5BZ in a temperature range of 120–140 °C. The TG-isothermal indicated a decrease in the temperature of conversion to 5BZ and its intensity, probably due to interaction with the lactose excipient contained in the sweetener.

A series of mono- and bimetallic catalysts of copper and nickel supported on silica were synthesized by the wet impregnation method. The obtained materials were characterized by X-ray diffraction (XRD) and thermal analysis (TG/DTG). From TG curves and applying the Vyazovkin model-free kinetics, the apparent activation energy ( E a ) related to the decomposition of Cu and Ni nitrates on the silica surface were determined. The obtained values were correlated to the catalytic activity of the materials on the reaction of nitrate degradation in water. The catalytic processes were carried out in a batch slurry reactor under continuous flow of hydrogen in the aqueous solution containing 200 ppm of nitrate. It was verified that the catalysts with lower activation energy presented higher catalytic activity.

In this work, the thermodynamic activation and kinetic study of mineral lubricant oils was accomplished using isothermal and non-isothermal thermogravimetry based on mass loss as a function of time and temperature. The thermodynamic and kinetic behavior of the mineral lubricant oils depends on the atmosphere and heating rates used in TG analysis. The kinetic and thermodynamic results were satisfactory, presenting good correlation, with a linear correlation coefficient close to unit with a low standard deviation.

Sulfonylureas are widely used for the treatment of non-insulin dependent diabetes mellitus. Glibenclamide belongs to the group of substituted arylsulfonylureas. Many representative of this group shows polymorphism. The purpose of this work was to investigate the thermal behaviour and compatibility between glibenclamide and some excipients using thermoanalytical techniques (TG-DTG/DSC). The thermal and isothermal kinetics data showed incompatibility between glibenclamide and magnesium stearate.

In the present study, powders based on Ca x Sr 1-x WO 4 tungstates, with a scheelite structure were synthesized, using the polymeric precursor method. The powder precursors, calcined at 300°C, were thermally characterized by TG/DTA. It can be observed that the mass loss basically takes place in three stages: first - dehydration, second - pyrolysis and third - elimination of the remaining organic material. The structural characterization was performed by XRD, after thermal treatment between 300 and 700°C. The crystallization takes place at 500°C, but more defined and intense diffraction peaks appeared at 700°C. Based on these XRD results the lattice parameters, crystallinity and crystallite size were calculated.

An unsaturated polyester/sisal flame retardant composite was formulated using decabromine diphenyl oxide associated with antimony trioxide as additives. The development and use of natural or vegetable fiber reinforced composites is increasing worldwide, since natural fibers come from renewable sources and their use contributes to the so-called 'green technology'. In the present study, the synergic effect of a bromine/antimony (3:1 molar ratio) based flame retardant system with 7.5p Br (mass/mass) added to composites investigated by TG, UL-94V and pyrolysis on a coupled Pyr-GC/MS device. The efficiency of the flame retardant system is confirmed by TG and UL-94V test where the composite containig flame retardant system obtained the highest classification (V-0).

AlMCM-41 molecular sieves were synthesized starting from a hydrogel with the following molar composition—4.58 SiO 2 :0.0485 Na 2 O:1 CTMABr:0.038 Al 2 O 3 :200 H 2 O. Cethyltrimethylammonium bromide (CTMABr) was used as structure template. The obtained materials were characterized by XRD, FT-IR and TG/DTG. The model-free kinetic algorithms were applied in order to determinate conversion, isoconversion and apparent activation energy to decomposition of the CTMA+ species from the AlMCM-41 materials.

The siliceous MCM-41 molecular sieve was synthesized starting from a hydrogel with the following molar composition: 4.58SiO2:0.437Na2O:1CTMABr:200H2O. The cetyltetramethylammonium bromide (CTMABr) was used as structure template. A kinetic study of template removal after the syntheses was performed by Vyazovkin model-free kinetic method obtaining apparent activation energy of 166±8.2 kJ mol-1.

Thermogravimetry is proposed to study the alumina catalyst regeneration deactivated by coke, after being used in the transformation of styrene in a fixed bed continuous flow reactor. The model-free kinetic approach has been applied to data for the thermal oxidation of carbonaceous deposits on the catalyst. The activation energy (E) was calculated as a function of a (conversion) and T (temperature), by using Vyazovkin model-free kinetic method, allowing to estimate time required to remove coke at a given temperature.

The standard molar enthalpy of formation of crystalline dialkyldithiocarbamate chelates, [Pd(S2CNR2)2], with R=CH3 and i-C3H7, was determined through reaction-solution calorimetry in 1,2-dichloroethane, at 298 K. Using the standard molar enthalpies of formation of the gaseous chelates, the homolytic (526±18 and 666±10) and heterolytic (2693±18 and 2957±10 kJ mol-1) mean enthalpies of palladium-sulphur bond dissociation were calculated.

In this work was studied the acid properties of a series of HZSM-12 zeolites with different Si/Al molar ratio. The samples of ZSM-12 were synthesized by the hydrothermal method starting from a gel with the following molar composition: 20MTEA:10Na2O:xAl2O3:100SiO2:200H2O, where: x=2, 1, 0.67 and 0.50, respectively. After the synthesis, the samples of ZSM-12 were ion-exchanged NH4Cl solution to obtain zeolite in the acid form (HZSM-12). The acid properties were evaluated by n-butylamine thermodesorption in a TG equipment at three different heating rates. The model-free kinetic model was applied in the TG integral curves to estimate the apparent activation energy (Ea) of the n-butylamine desorption process. The results obtained showed that the HZSM-12 zeolite presents two kinds main of acid sites: one with Ea in the range of 115-125 kJ mol-1 classified as weak and other kind with Ea varying of 230-250 kJ mol-1 classified as strong.

The coke removal of HZSM-12 zeolite deactivated in the reaction of n-heptane cracking was studied by thermogravimetry using two multiple heating rate integral kinetics models proposed by Ozawa-Flynn-Wall and Vyazovkin to obtain the activation energy of process of thermoxidation of coke. The results obtained by both models presented excellent accordance with the related literature.

Thermogravimetry is proposed for studying the alumina catalyst regeneration deactivated by coke, after being used in the transformation of styrene in a fixed bed continuous flow reactor. The model-free kinetic approach has been applied to data for thermal oxidation of carbonaceous deposits on the catalyst. The activation energy (E) was calculated as a function of conversion (α) and temperature (T), by using Vyazovkin model-free kinetic method, allowing to estimate time required to remove coke for a given temperature.