Theses and Dissertations

Tao Ding

Issuing Body

Mississippi State University

Advisor

Rogers, Rudy E.

Committee Member

George, Clifford E.

Committee Member

Toghiani, Hossein

Committee Member

Hill, Priscilla

Date of Degree

12-11-2004

Document Type

Graduate Thesis - Open Access

Major

Chemical Engineering

Degree Name

Master of Science

College

James Worth Bagley College of Engineering

Department

Dave C. Swalm School of Chemical Engineering

Abstract

Reducing atmospheric CO2, a main source of greenhouse gas, has been accentuated recently. One focus is capture, separation, and sequestration of industrial CO2. As a hydrate former, CO2 forms hydrates at moderate temperatures and pressures. This phenomenon could be utilized to capture and separate CO2 from flue gases, and also has the potential to sequester CO2 in the deep sds. This research investigated the CO2-N2 separation efficiency of gas hydrates; it investigated the sequestration potential of CO2 hydrates in ocean sediments. The catalytic effect of surfactants in these processes was investigated. A fluorosurfactant FS-62 was mixed with SDS at 100ppm/1000ppm was found to best catalyze CO2 hydrate formation, giving a high formation rate of 0.1239 mmole of occluded gas/minute-about 2.87 times the base case with no surfactant. FS-62/SDS was verified to increase the separation efficiency of N2-CO2 gas which formed a mixture gas hydrate. In a two-stage process, a desirable separation efficiency was obtained. A total CO2 removed from the gas mixture of 67.7% was obtained. In a series of experiments simulated under ocean sediment environments, the biosurfactants Emulsan and Rhamnolipid showed favorable catalysis of CO2 hydrate formation. Also, the chemical structure of the porous media was found to have some influence on the hydrate formation rate. For a quiescent system, the displacement of natural gas from hydrate by injecting CO2 occurred at a low level and would not be a practical process. In the case of displacing CH4 from hydrate with CO2, no displacement would occur. This research work showed that a potentially cost effective hydrate separation technology applied to N2-CO2 gas, representative of a flue gas, can be improved by adding surfactants. It was found that biosurfactants give some beneficial effect on CO2 hydrate formation in sediments and might be used to assist CO2 sequestration in sediments or to displace natural gas from hydrates already in sediments.

URI

https://hdl.handle.net/11668/19170

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