Search

A model for deoxygenation of vegetable oil components of renewable diesel manufacturing is proposed. The conversion of triglycerides over the deoxygenation catalyst in the presence of hydrogen were evaluated by including the rigorous kinetic data of complex reactions that happen in parallel and/or consecutively, including saturation, hydrogenation, hydrogenolysis, cracking, decarboxylation, decarbonylation, hydrodeoxygenation, methanation, and water-gas shift. A fixed-bed reactor was modeled using Aspen Plus® 8.8 software. The influence of reactor pressure, temperature, and H2/oil molar ratio was analyzed, in addition to type of feedstocks. The operational conditions in reactor considered optimized in this study for the deoxygenation of vegetable oils process were pressure 40 bar, temperature 300 °C, and H2/oil molar ratio of 2.5/1. For all oils analyzed, a conversion above 96% was observed, and the overall mass yields obtained from these in diesel-like hydrocarbons were > 78%. In addition, it was noted that the type and amount of hydrocarbon converted are mainly related to the initial composition of vegetable oil used as feedstock. Conclusively, the model proposed can be used for new product design, improving operation conditions, and help economic analysis in green diesel manufacturing.

In the present paper, an integrated continuous process of biodiesel manufacturing is proposed using Aspen Plus simulator for different feedstocks. Majority of the reported simulation models in literature are design models for new processes by fixing some level of equipment performance such as the conversion in reactor. Most models assume the feed oil as pure triglycerides or some fatty acids and the biofuel as pure ester. In order to optimize the production of biodiesel, similarity with reality is necessary. For this purpose, this work uses thermophysical property estimation of glycerides, rigorous reaction kinetics, phase equilibrium for separation and purification units, and prediction of essential biodiesel fuel qualities. Detailed operating conditions, equipment designs, and properties of feed and products were obtained. The reactions and parameters kinetics were applied to represent both methanolic and ethanolic transesterification of the biodiesel production. An evaluation of optimal operating conditions (time, temperature, alcohol: oil ratio) for a CSTR reactor was determined. The optimal conversion was achieved at a temperature of 60 °C, 6.00 mol/mol alcohol-oil ratio and 2.0 h residence time when used methanol transesterification reaction as 88.19, 93.77, 89.43, and 89.25%, respectively for sunflower, soybean, palm and macauba oil, on the other hand 86.09, 80.26, 76.54, and 76.39% for transesterification ethanolic. Most of the biodiesel obtained from the simulations presented adequate according to the specifications of the D6751, ANP 45, and EN 14214 standards. Finally, the model proposed can be used for improving operations conditions, new products design and help economic analysis in continuous processes of biodiesel production.

Researches focusing on the development of biofuel production processes have increased significantly in recent years, mainly for environmental and economic issues. The identification of low-cost raw materials and the development of simulation models able to predict the conditions of production and the properties of the components may be the way to optimize these processes. Biodiesel is an alternative renewable fuel to petroleum-based diesel departing from vegetal oils (fresh or reused) as well as some kinds of animal tallows. The knowledge of thermophysical properties of the components of the feed is crucial for optimization this process. The experimental determination of these properties is complex and high costs, as can occur chemical degradation during analysis or it is impossible to have them this like pure components. Thus, the objective of this study was to evaluate methods for predicting physical and thermodynamic properties, in order to develop a database of the compounds involved in the biofuels production's process and to recommend appropriate methods based on accuracy and consistency of data obtained. In view of that, this work investigated the performance of groups contribution methods and fragment-based approach in the calculation of as normal boiling temperature, critical temperature, critical pressure, critical volume, acentric factor, heat capacity, vapor pressure, enthalpy of vaporization liquid density and enthalpy of formation. At the end of this work, the most viable models were recommended for each property evaluated, comparing the estimated values to the experimental data available in the literature. Finally, a database with physical and chemical properties of vegetable oils was created to use in engineering calculations.

In this work, Ca(OH)2 nanoplates supported on activated carbon (AC) were used to efficiently remove free fatty acids (FFA) from soybean oil. SEM, TEM, XRD, TG, Zeta potential measurements showed that Ca(OH)2 nanoplates with average dimensions of 100–300 nm and crystallite size 17 nm supported/dispersed on the surface of the AC are very efficient to remove FFA by a reactive adsorption. Experiments with oleic acid 20% in soybean oil and Ca(OH)2 dosages varying from 5 to 60 mg mL−1 reached near 100% removal of FFA. The data suggest a reactive adsorption of oleic acid (OA) to form Ca(oleate)2 impregnated on the AC surface which can be easily removed from soybean oil. On the other hand, pure Ca(OH)2 nanoparticles or commercial reacts with OA to form a paste which cannot be separated. The Ca(OH)2/AC composite can be used as a FFA trap to allow biodiesel synthesis from soybean oil with 5 and 10% FFA using the classical basic NaOH homogeneous catalyst.

A disponibilidade de matéria-prima de baixo custo é o fator chave para a viabilidade econômica na produção de biodiesel. Conjuntamente com a matéria-prima, outros fatores que elevam os custos no processo de transformação do óleo vegetal ou gordura animal em biodiesel por transesterificação alcalina estão associados às etapas de purificação da matéria-prima e dos produtos. A macaúba (Acrocomia aculeata) é uma oleaginosa em foco no Estado de Minas Gerais, cuja atual forma extrativista de obtenção a classifica como matéria-prima de acidez elevada, portanto não apta para a produção de biodiesel por processos convencionais. Propõe-se, neste trabalho, o projeto de uma planta industrial contendo uma etapa alternativa de separação dos ácidos graxos livres do óleo da polpa do fruto da macaúba, tecnicamente viável e ambientalmente correta, visando à adequação desse óleo para a produção de biodiesel por transesterificação etílica via catálise alcalina homogênea. O pré-tratamento é constituído por duas etapas principais: extração líquido-líquido para recuperação dos ácidos graxos livres e esterificação heterogênea para neutralização dos ácidos graxos residuais. Na simulação, 50 kg.h-1 de óleo de macaúba com acidez de 12,92% são tratados, alcançando-se 40,8 kg.h-1 de produto com 0,5% de acidez. Na validação em teste de bancada, seguindo-se as mesmas etapas da simulação, alcançou-se um produto com acidez de 0,67%.