• Energy Research

Abstract In line with the aim to minimize climate change and dependence on fossil fuels, there is an increasing demand from different transport sectors for non-oxygenated and low-cost biofuels. In this study, bio-hydrocarbons were synthesized from macauba oils, which is a new and promising biofuel feedstock. These fatty materials were subjected to deoxygenation reactions over beta zeolite and ZSM-5 catalysts with different acidities (Si/Al ratio). Other parameters such as the reaction atmosphere (N2 or H2), catalyst calcination time, feedstock composition, and reaction time were also investigated. A preliminary study of the deoxygenation reaction kinetics indicated a higher conversion rate of hydrocarbons using beta zeolite, achieving a conversion of 100% in 3 h. The products were categorized into different compounds classes, such as linear, cyclic, branched, and aromatic hydrocarbons. The longer calcination time of the non-noble metal catalyst (15 h) and the use of hydrogen resulted in a high degree of deoxygenation. A higher percentage of hydrocarbons was obtained using an already hydrolyzed macauba pulp oil, with high initial acidity (38% m/m), and 10 bar H2. This feedstock and the innovative process provide low-cost alternatives to produce drop-in biofuels on a large scale.

Biodiesel is an alternative fuel that has been used for partial or total substitution of diesel to reduce its environmental impacts. Prior studies on this topic have focused on the quest for better synthesis process, new catalysts and low-cost non-food and raw materials to improve the economic and sustainable production as well as product quality. In this study, acidic oil from macauba, a palm tree native to South America that has no food uses, was converted into biodiesel. The esterification and transesterification reactions were performed with methanol, ethanol and isobutanol with the goal of improving the cold properties of the biodiesel. The isobutyl ester exhibited the lowest freezing point temperature but underperformed outside of international specifications for kinematic viscosity; it also exhibited a low ester content. The methyl and ethyl esters were within the specifications of the international standards for ester content, density, kinematic viscosity and sulphur content. The ethyl ester produced from macauba oil displayed better properties in cold conditions than methyl and isobutyl esters studied here, with a cold filter plugging point of 0 °C. Its onset crystallisation temperature was reduced from −5.96 to −13.41 °C when subjected to fractional crystallisation. The ethyl ester exhibited the best lubricity value among the other esters studied.

In this study, Ca–Al mixed oxide produced from the thermal decomposition of a synthetic hydrocalumite was prepared and evaluated as a catalyst in the transesterification reaction for biodiesel production, using the following reagents: refined soybean oil, crude macauba kernel oil, methanol, and ethanol. The synthetic hydrocalumite and the mixed oxide were characterized by powder X-ray diffraction, thermogravimetry–differential scanning calorimetry coupled with mass spectrometry, specific surface area measurement, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and temperature-programmed desorption of CO2. The catalytic tests indicated that the reactions using methanol exhibited more favorable activity than those employing ethanol, regardless of the type of oil used (soybean or macauba). Ethanolysis produced better results for the higher-molar-mass oil (soybean), because of the effect of the ethanol cosolvent. The catalyst was efficient for transesterification, with conversions of 97% a...

Abstract Biomass conversion into liquid products of interest for the fuel formulations has been draw remarkable attention to reducing the environmental pollution in the world. Biofuels play an important key to mitigating climate changes from the development of sustainable processes. Drop-in biofuels are oxygen-free biofuels composed by liquid hydrocarbons obtained from renewable sources. In the present work, a screening with different catalysts was performed for soybean oil deoxygenation. The niobium phosphate catalyst (NbOPO4) showed a great performance in the production of drop-in fuels in different conditions of reaction. The hydrocarbon yields are in the range of 76–90% (wt%). The redox and acid properties of NbOPO4 led to the simultaneous formation of bio-hydrocarbons, such as linear (38%) and branched alkanes (14%), cycloalkanes (1%), olefins (1%) and aromatics (36%) compounds. NbOPO4 exhibits higher selectivity to bio-jet fuel (58%), followed by green diesel (37%) and biogasoline (21%). This sustainable route to produce bio-hydrocarbons brings a process using N2 gas instead of H2 gas. This is an innovative, sustainable, efficient, safe and low-cost technology with great potential for industry application.

Drop-in fuels have attracted great interest for automotive and aeronautical use. In this work, bio-hydrocarbons were obtained from palm kernel oil (palmist oil) within the distillation range of diesel and jet fuel. Green fuels were produced through the hydrodeoxygenation of palmist fat and its hydrolyzed product by using Pd/C as a catalyst. The process is efficient for hydrodeoxygenation with conversions of up to 96% after 5 h of reaction, at 10 bar of H2 pressure and 300 °C, which are mild conditions compared with the majority of the processes described in the literature. The hydroprocessing products were analyzed by infrared spectroscopy, thermal analysis and gas chromatography–mass spectrometry. The freezing temperatures of the biofuels were determined by DSC. Up to 5% deoxygenation products can be used in commercial jet fuel without compromising the cold fuel properties.

Biodiesel is a biofuel that is of great importance; its good performance is associated with its purity mainly related to a high content of fatty acid alkyl esters, quantified by gas chromatography (GC), liquid chromatography (LC), hydrogen nuclear magnetic resonance (1H-NMR) and infrared (FTIR) spectroscopy. However, these methodologies take long a time and are relatively expensive. Herein, thermogravimetric analysis (TGA) and viscometry (VA) are studied as alternative methods for the quantification of alkyl esters (FAME and FAEE). Analytical curves from the viscosity and mass loss percentage (TGA) as a function of methyl and ethyl ester levels on binary mixtures (soybean biodiesel/soybean oil) were constructed. The correlations experimentally obtained were presented and used to quantify biodiesel content in the products of ethanolysis and methanolysis and in biodiesel/vegetable oil mixtures of different feedstocks. This comparative study confirmed that both alternative methods are adequate to be used. A single viscometry analytical curve could be used to analyze products, obtained by different oleaginous plants, if their oils exhibit similar viscosities. Viscometry can be the most suitable alternative technique because it is portable, fast, less sensitive to the presence of intermediates than thermogravimetric analysis, easy to work with and very inexpensive.

Abstract In recent years, there has been a strong global interest in developing technologies for converting renewable and low-cost raw materials into green diesel and bio-jet fuel, which are made of hydrocarbons. In this work, cashew nut shell liquid (CNSL), which is an industrial waste, was used as a feedstock to produce green diesel. Different reaction conditions during the upgrading process (deoxygenation, hydrogenation and cracking) were evaluated using palladium over activated charcoal (Pd/C) as a catalyst. The catalyst was characterized by X-ray diffraction and specific surface area analysis. The influences of the reaction parameters, such as temperature (180, 250 and 300 °C), time (5 and 10 h) and pressure (10, 20, 30 and 40 bar), were investigated using 10% w/w Pd/C. The composition of the products was determined using gas chromatography coupled with mass spectrometry and infrared spectroscopy. Higher pressures and temperatures led to a higher degree of deoxygenation and hydrogenation. In contrast, lower pressures or temperatures resulted in higher degrees of cracking. From the optimization experiments, a 98% yield of hydrocarbons corresponding to the diesel range was obtained under a 40 bar H2 atmosphere at 300 °C, 10 h, and 500 rpm (in a batch reactor). Of these hydrocarbons, 89% were saturated alkanes, 3% were aromatic compounds and 6% were oxygenated compounds. This new and sustainable route is promising because it involves the conversion of a low-value residue into green diesel using mild experimental conditions. Biofuel production from CNSL allows the total valorization of the residues in the cashew-nut agroindustrial chain and has potential industrial applications in many countries.

Abstract Wood tar pitches are generated as by-products by the charcoal manufacturing industry. They have a macromolecular structure constituted mainly by phenolic, guaiacylic, and siringylic units common to lignin. Due to their characteristics, biopitches are been investigated as precursors of carbon materials such as carbon fibers, bioelectrodes and activated carbons. In the present work the structural evolution of Eucalyptus tar pitches under carbonization is investigated, which is important for the improvement of planning and control of pitch processing and end-product properties during carbon material production. The studies involve X-ray diffraction and infrared analyses, besides helium density, BET surface area and BJH pore volume measurements. The results showed that the conversion of pitch into carbon basically involves three steps: (1) Up to around 600 °C the material has an highly disordered structure, being the release of aliphatic side chains and volatiles the main events taking place. (2) Between 600 °C and 800 °C, condensation of aromatic rings occurs to form bi-dimensional hexagonal networks so that micro- and mesoporosity are developed. The 800 °C-coke is constituted by two phases: one highly disordered and another more crystalline. (3) Over 800 °C, both phases are gradually ordered. As defects are gradually removed, surface area and porosity decrease, approaching zero for the 2100 °C-coke.

Abstract An NBR/polyvinyl chloride (PVC) blend changed by aging (20 weeks in different fuels at room temperature) was evaluated for weight, hardness, mechanical properties, and microstructure. The exposure tests were made with premium gasoline, regular gasoline, regular gasoline doped with a rubber solvent, and an oxygenated renewable biofuel (ethanol fuel). After the aging tests, all NBR/PVC blend samples increased in both hardness and elastic modulus, whereas both elongation at break and tension at break decreased, but in different proportions. As the NBR/PVC blends aged, they became less elastomeric and more rigid. The regular gasoline doped with a rubber solvent was the most aggressive of the fuels tested because it promoted the extraction of a large quantity of the blend constituents, thus making the blend harder. In general, NBR/PVC samples immersed in the fuels showed similar mechanical behaviors, except in the case of immersion in ethanol. The values of parameters τ3 and I3 were obtained by positron annihilation lifetime spectroscopy. The changes in the mechanical properties and the reduction of the values of parameters τ3 and I3 were related to extraction of the plasticizer, which was confirmed by thermogravimetric analysis.

This study aimed to evaluate the effect of medium composition and culture conditions on lipid content, fatty acid profile and biomass production by the yeast Yarrowia lipolytica QU21. Lipid production by the yeast growing on glycerol/(NH4)2SO4 (10%/0.1%) reached 1.48g/L (30.1% according to total cell dry weight). When glycerol was replaced by crude glycerol (industrial waste), the lipid yield was 1.27g/L, with no significant difference. Some particular fatty acids were found when crude glycerol was combined with fresh yeast extract (FYE, brewery waste), as linolenic acid (C18:3n3), eicosadienoic acid (C20:2), eicosatrienoic acid (C20:3n3) and eicosapentaenoic acid (C20:5n3). In addition, the FYE promoted an increase of more than 300% on polyunsaturated fatty acid content (PUFA), which is an undesirable feature for biodiesel production. The fatty acid composition of the oil produced by Y. lipolytica QU21 growing on crude glycerol/(NH4)2SO4 presented a potential use as biodiesel feedstock, with low PUFA content.