Oxidation kinetics of biodiesel from soybean mixed with synthetic antioxidants BHA, BHT and TBHQ: Determination of activation energy

Borsato, Dionísio; Cini, João Rafael de Moraes; Silva, Hágata Cremasco da; Coppo, Rodolfo Lopes; Angilelli, Karina Gomes; Moreira, Ivan; Maia, Elaine Cristina Rodrigues

doi:10.1016/j.fuproc.2014.05.033

Cited by 84 publications

(39 citation statements)

References 25 publications

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“…Biodiesel is a generic term for fuels with properties generally similar to diesel that are produced from sustainable and renewable energy sources for use in compression ignition vehicles [1,2]. Biodiesel has a promising future if technical obstacles such as environmental impacts and high prices for petroleum and its derivatives can be overcome.…”

Section: Introductionmentioning

confidence: 99%

Determination of kinetic and thermodynamic parameters of the B100 biodiesel oxidation process in mixtures with natural antioxidants

Spacino

Borsato

Buosi

et al. 2015

Fuel Processing Technology

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Section: Introductionmentioning

confidence: 99%

Determination of kinetic and thermodynamic parameters of the B100 biodiesel oxidation process in mixtures with natural antioxidants

Spacino

Borsato

Buosi

et al. 2015

Fuel Processing Technology

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“…This simple approach is taken on the assumption that the water absorber conductivity is linearly correlated to the concentration of ROOH produced by the oxidation. Similar approach has also been employed in published literature to determine oxidation rate constants and activation energy of true biodiesels [18,20]. The water absorber conductivity vs. time data are also used to determine the OIP values, although these are not directly related to the kinetic parameters sought after in this work.…”

Section: Methodsmentioning

confidence: 99%

“…The activation energy of BHT obtained in this work is significantly higher than values reported in the literature. Borsato and coworkers [20] reported an activation energy of 81.72 kJ/mol for the oxidation of soybean oil B100 biodiesel with the addition of approximately 1000 ppm BHT. Jain and Sharma [27] reported activation energy of jatropha B100 biodiesel containing BHT that increases linearly with antioxidant dose, based on nonisothermal first-order kinetic data treatment.…”

Section: Primary Oxidation Kinetic Parameters Measurementmentioning

confidence: 99%

Measurement of Antioxidant Effects on the Auto-oxidation Kinetics of Methyl Oleate – Methyl Laurate Blend as a Surrogate Biodiesel System

Samadhi

Hirotsu

Goto

2017

Bull. Chem. React. Eng. Catal.

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This research investigates the feasibility of methyl oleate-methyl laurate blend as a surrogate biodiesel system which represents jatropha-coconut oil biodiesel, a potentially suitable formulation for tropical climate, to quantify the efficacy of antioxidant additives in terms of their kinetic parameters. This blend was tested by the Rancimat EN14112 standard method. The Rancimat tests results were used to determine the primary oxidation induction period (OIP) and first-order rate constants and activation energies. Addition of BHT and Ecotive TM antioxidants reduces the rate constants (k, h -1 ) between 15 to 90% in the 50-200 ppm dose range, with Ecotive TM producing significantly lower k values. Higher dose reduces the rate constant, while oleate/laurate ratio produces no significant impact. Antioxidants increase the oxidation activation energy (Ea, kJ/mol) by 180 to almost 400% relative to the nonantioxidant value of 27.0 kJ/mol. Ecotive TM exhibits lower Ea, implying that its higher efficacy stems from a better steric hindrance as apparent from its higher pre-exponential factors. The ability to quantify oxidation kinetic parameters is indicative of the usefulness of methyl oleate-laurate pure FAME blend as a biodiesel surrogate offering better measurement accuracy due to the absence of pre-existing antioxidants in the test samples.

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“…[3][4][5] It was also reported that hydrolysis reactions can occur depending on the environmental humidity or even on the humidity present in the storage tanks. Residual water is particularly problematic because it can hydrolyze the biodiesel, producing free fatty acids and alcohol and increasing the acid number of biodiesel.…”

Section: Introductionmentioning

confidence: 99%

“…28, No. 4,2017 Another type of oxidation reaction that biodiesel can undergo is the photo-oxidation. Free radicals, which are known as initiators of oxidation processes, are formed as a result of photo-chemical reactions.…”

mentioning

confidence: 99%

Influence of Water and Ultraviolet Irradiation on the Induction Period of the Oxidation of Biodiesel

Silva¹,

Salomão²,

Vila³

et al. 2016

Journal of the Brazilian Chemical Society

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Biodiesel degrades due to oxidative processes, causing a decrease in its quality. In the present work, it has been clearly shown that the incidence of ultraviolet radiation on biodiesels obtained from soy, canola, linseed and microalgae oils initiate oxidative processes which lead to the decrease in the induction period (IP) of the fuel. The influence of the residual water content of the same biodiesels on the oxidation process was also investigated with and without the incidence of ultraviolet radiation. Between 190 and 850 ppm of water in the biodiesel and without UV irradiation, no significant change in the IP values was observed under the experimental conditions. Keywords: biodiesel, oxidative stability, photo-oxidation, residual water IntroductionBiodiesel is a biofuel derived from renewable sources such as vegetable oils and animal fats. It presents physicochemical characteristics similar to that of petrodiesel and can therefore be directly used in diesel engines. Because biodiesel is produced from renewable and biodegradable raw materials, it presents some advantages over petrodiesel, for example, the absence of sulfur in emissions, a high flash point, and good lubricity. 1,2 Biodiesel is composed of a mixture of alkyl esters, usually methyl or ethyl derivatives, obtained through transesterification reactions of vegetable oils and animal fats with methanol or ethanol in the presence of a catalyst.Oxidation reactions of biodiesel can occur on account of various factors, such as high unsaturation and total number and position of allylic and bis-allylic carbons that are adjacent to the double bonds of the molecules of alkyl esters, exposure to light, temperature, presence of transition metals, and exposure to oxygen. [3][4][5] It was also reported that hydrolysis reactions can occur depending on the environmental humidity or even on the humidity present in the storage tanks. Residual water is particularly problematic because it can hydrolyze the biodiesel, producing free fatty acids and alcohol and increasing the acid number of biodiesel. 6Similar to lipids, the oxidation of biodiesel occurs mainly through two processes called auto-oxidation and photo-oxidation. Auto-oxidation is the main cause of the oxidation of biodiesel. It involves the formation of free radicals and can be summarized in three steps called initiation, propagation, and termination, as schematized in Figure 1. 7 In the first phase, known as the induction or initiation period, the initial formation of free radicals occurs. In the second phase, known as propagation, the formation of a great quantity of peroxides and hydroperoxides occurs. Finally, the termination step occurs, forming high concentrations of degradation products, such as alcohols, aldehydes, ketones, organic acids, and polymers, whose presence changes the properties of the biodiesel. Vol. 28, No. 4, 2017 Another type of oxidation reaction that biodiesel can undergo is the photo-oxidation. Free radicals, which are known as initiators of oxidation processes, are formed as a...

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Oxidation kinetics of biodiesel from soybean mixed with synthetic antioxidants BHA, BHT and TBHQ: Determination of activation energy

Cited by 84 publications

References 25 publications

Determination of kinetic and thermodynamic parameters of the B100 biodiesel oxidation process in mixtures with natural antioxidants

Determination of kinetic and thermodynamic parameters of the B100 biodiesel oxidation process in mixtures with natural antioxidants

Measurement of Antioxidant Effects on the Auto-oxidation Kinetics of Methyl Oleate – Methyl Laurate Blend as a Surrogate Biodiesel System

Influence of Water and Ultraviolet Irradiation on the Induction Period of the Oxidation of Biodiesel

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