Nahid Khatibi

Date of Award

January 2012

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Chemical Engineering

First Advisor

Wayne Seames

Second Advisor

Brian Tande

Abstract

Aromatics, such as benzene and toluene, are important for the production of many materials such as polystyrene and other polymers. Benzene and toluene are, most commonly produced from crude oil. But due to the depletion of petroleum resources, the world is looking for renewable alternatives.

Studies of the catalytic cracking of triacylglycerol containing oils (TAG), such as soybean oil, have demonstrated that a high concentration of aromatics can be produced under certain conditions. This discovery provides an opportunity to develop a pathway for the production of aromatics from renewable resources. The main focus of this research was to develop the process conditions that are required to recover aromatics from cracked soybean oil using sulfolane as a solvent and to outline the process steps necessary for recovering and purifying the target aromatics from the solvent. To achieve these objectives, simulations and experiments were performed. The primary objective of this thesis was to find the optimum conditions for the maximum extraction yield. Another objective was to estimate the overall cost of a viable process.

Using 20 mL test tubes, lab scale screening experiments were performed, and two major variables were investigated by using full factorial statistical design experiments. The two variables were the temperature of the mixer vessel and the solvent to solute ratio. Other variables, such as initial pressure, stirring rate, feedstock quantity, and residence-time, were kept constant. The predicted variables that were used to determine the optimal operating conditions were fraction of fatty acid solute extracted by the sulfolane solvent and the quality of the chemical compositions of the final product. Gas Chromatographic (GC-MS) analysis was used to identify and quantify the chemical composition of the samples.

The range of 3-to-1 to 11-to-1 ratio of sulfolane to BTEX present in the distilled crackate was explored. The optimum yield was found to occur at the 9-to-1 ratio of solvent-to-solute and higher. The optimum temperature was concluded to be 50°C among three temperatures of 30°C, 50°C and 70°C. The recovery of benzene and toluene in the LLE process were determined to be around 80% and 70%, respectively for a single stage extraction. It was calculated that a 3-stage extraction system will result the 99.5% recovery for benzene and toluene. The best purification scheme (of 3 studied) was, three columns in series with the column 1 light key being benzene, column 2 light key toluene, and column 3 heavy key sulfolane. The slightly greater NPV@12%, $31 million, and DCFROR, 49%, belonged to this configuration

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