Li, Huixing
(2008)
SELECTIVE CATALYTIC OXIDATION OF HYDROGEN SULFIDE FROM SYNGAS.
Master's Thesis, University of Pittsburgh.
(Unpublished)
Abstract
In order to obtain a non-corrosive fuel gas (syngas), which is derived from coal by Integrated Gasification Combined Cycle (IGCC) technology and used in power plants, hydrogen sulfide (H2S), which is generated during the gasification process due to sulfur contained in coal, should be removed to protect instruments, especially turbines, from corrosion. To improve H2S removal efficiency and develop excellent regenerative catalyst, we conducted the following research. Simulated syngas was introduced into a fixed-bed quartz reactor where carbonaceous sorbents (which are excellent sorbents and have lower price) were positioned to capture H2S. Tail gases from the outlet of the reactor including H2S, COS, and SO2 were continuously monitored by a residual gas analyzer (or mass spectrometer) to determine the capacity of H2S uptake and selectivity of adsorption/oxidation by different sorbents. Carbonaceous materials including carbon black, graphite and activated carbon fibers (ACFs) were compared for the application in desulfurization. Rare earth metal oxides (La2O3 and CeO2) were investigated and used to modify ACFs due to their potential to effectively remove H2S and multicycle regenerative ability. Water vapor and temperature effects on H2S removal were studied. Functional groups on carbonaceous materials were determined and the mechanism of the promotion of H2S uptake by basic functional groups was proposed. Through the determination of activation energy of desorption of sulfur species from sulfided sorbents, it is concluded that chemisorption is the dominant mechanism at higher sulfurization temperature, while physisorption is the controlling process at lower temperature. At the temperature ranging from 110 to 170 ¡ãC, the best H2S-uptake capacity was obtained because chemisorption and physisorption are both present and water film on the surface of sorbents is ideally maintained. The observation of sulfurization and regeneration of sorbents and by-products related that nitrogen could only remove physically adsorbed H2S and hydroxide could, to some extent, restrain the formation of by-products (the reaction between COS or SO2 and hydroxide). ACFs modified by metal compounds showed excellent H2S-uptake capacity (up to 35 mg H2S/g Sorbent) in the 1st cycle but the capacity in the subsequent cycles were much lower than the 1st cycle because regeneration gas (nitrogen) could not recover the chemically adsorbed sulfur species.
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Details
| Item Type: |
University of Pittsburgh ETD
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| Status: |
Unpublished |
| Creators/Authors: |
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| ETD Committee: |
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| Date: |
9 June 2008 |
| Date Type: |
Completion |
| Defense Date: |
1 April 2008 |
| Approval Date: |
9 June 2008 |
| Submission Date: |
4 April 2008 |
| Access Restriction: |
No restriction; Release the ETD for access worldwide immediately. |
| Institution: |
University of Pittsburgh |
| Schools and Programs: |
Swanson School of Engineering > Civil and Environmental Engineering |
| Degree: |
MSCE - Master of Science in Civil Engineering |
| Thesis Type: |
Master's Thesis |
| Refereed: |
Yes |
| Uncontrolled Keywords: |
Adsorption; Carbon; Hydrogen Sulfide; Regeneration; Sulfurization; Syngas |
| Other ID: |
http://etd.library.pitt.edu/ETD/available/etd-04042008-145554/, etd-04042008-145554 |
| Date Deposited: |
10 Nov 2011 19:34 |
| Last Modified: |
15 Nov 2016 13:38 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/6736 |
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