Kinetics and Reaction Pathways of Naphthenic Acids Model Compound Reaction with Subcritical Methanol for Total Acid Number Reduction

Naphthenic acids are the primary contributor to the total acid number of the oil and it can be expressed in terms of total acid number (TAN). This paper studies on the reaction mechanism of naphthenic acids model compound upon reacting with subcritical methanol. It also discusses further on the k...

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Main Author: A/P Nagarajan, Thasvinya
Format: Final Year Project
Language:English
Published: IRC 2015
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Online Access:http://utpedia.utp.edu.my/15813/1/Final%20Dissertation_Thasvinya_16847.pdf
http://utpedia.utp.edu.my/15813/
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Summary:Naphthenic acids are the primary contributor to the total acid number of the oil and it can be expressed in terms of total acid number (TAN). This paper studies on the reaction mechanism of naphthenic acids model compound upon reacting with subcritical methanol. It also discusses further on the kinetics and reaction pathways of the model compounds of naphthenic acids after reacting with subcritical methanol. Crude oil containing these acids which are corrosive can cause many problems such as equipment failures, high maintenance cost, reduce product quality and environmental disposal problems. The model compound; cyclopentane carboxylic acid with a molecular structure of C6H10O2 and z = -2 will be tested with subcritical methanol under temperature range from 180℃ to 220℃ with a temperature interval of 20℃ in 25 ml hydrothermal autoclave reactor. The reaction time for the mixture is from 10 min to 30 min with a time interval of 10 min. The well-known Peng-Robinson equation of state will be used to compute the amount of methanol by fixing the temperature and methanol partial pressure. From this experiment, the highest TAN reduction is achieved at 220℃ and 30 minutes where the reduction is about 17.56%. Upon the reaction, the components present in the sample were identified through GC/MS analysis. Reaction pathways for each sample is identified and there are production of ester, alcohol and alkene. From the results obtained, it is proved that the reaction is first order kinetics and independent with concentration. The value of activation energy obtained through the Arrhenius plot is 59.8966 J/mole-K and the value of pre-exponential factor, A is 260.05 s-1. This shows that subcritical methanol able to lower the reaction activation energy and also increases the speed of reaction. To sum up, it is proven that the subcritical methanol is an effective way to reduce the total acid number in crude oil.