Neumann, Dirk Walter Ralf
(2003)
Dynamic Reactor Operation and High-Temperature Catalysis:Direct Oxidation of Methane in a Reverse-Flow-Reactor.
Doctoral Dissertation, University of Pittsburgh.
(Unpublished)
Abstract
Synthesis gas, a mixture of H2 and CO, is a key intermediate product in the petrochemical industry, where it is used e.g. for the production of methanol and liquid fuels (via Fischer-Tropsch synthesis), or as a source of hydrogen for ammonia synthesis and fuel cells. An interesting alternative for the production of syngas to the conventionally used steam-reforming of methane (SRM) is catalytic partial oxidation of methane (CPOM) [1]. Here, methane is converted in a one-step process with oxygen or air over noble metal catalysts to synthesis gas. The reaction is characterized by extremely short contact times (ƒä < 50 ms) and very high temperatures exceeding 1000¢XC. While thermodynamics allow for optimum syngas yields, a complex interaction between total and partial oxidation reactions limits these under autothermal operation. A way to overcome these autothermal limitations is by increasing catalyst temperatures, e.g. in a multifunctional reactor concept. A particularly efficient heat-integration is achieved in the dynamically operated reverse-flow reactor (RFR) [2] through periodic switching of the direction of the gas flow in the reactor. We built a computer-controlled, laboratory-scale RFR for CPOM to gain general insights into the reaction behavior in this multifunctional reactor configuration. Experimental results demonstrate that total oxidation of methane can be reduced effectively, resulting in strongly increased syngas yields compared to autothermal reactor operation without heat integration. Furthermore, maximum attainable syngas yields are shifted towards even shorter contact times compared to a conventional process, allowing for even higher space-time yields. In addition, experiments reveal that dynamic reactor operation intrinsically counteracts catalyst deactivation. Detailed numerical simulations using elementary step kinetics are performed to investigate the influence of dynamic reactor operation on surface kinetics and reaction mechanism. It is shown that the reaction mechanism is characterized by methane partial and total oxidation reactions at the catalyst front edge, followed by endothermic reforming reactions in the second half of the catalyst bed, which occur due to advantageous temperature profiles in dynamic reactor operation. Overall, the RFR is a promising configuration for efficient, small-scale production of syngas.
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Details
| Item Type: |
University of Pittsburgh ETD
|
| Status: |
Unpublished |
| Creators/Authors: |
| Creators | Email | Pitt Username | ORCID  |
|---|
| Neumann, Dirk Walter Ralf | din1@pitt.edu | DIN1 | |
|
| ETD Committee: |
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| Date: |
3 September 2003 |
| Date Type: |
Completion |
| Defense Date: |
23 July 2003 |
| Approval Date: |
3 September 2003 |
| Submission Date: |
25 June 2003 |
| Access Restriction: |
No restriction; Release the ETD for access worldwide immediately. |
| Institution: |
University of Pittsburgh |
| Schools and Programs: |
Swanson School of Engineering > Chemical Engineering |
| Degree: |
PhD - Doctor of Philosophy |
| Thesis Type: |
Doctoral Dissertation |
| Refereed: |
Yes |
| Uncontrolled Keywords: |
Catalytic Partial Oxidation of Methane; Dynamic Reactor Operation; Synthesis Gas; Multifunctional Reactor Concept; Reverse-Flow-Reactor |
| Other ID: |
http://etd.library.pitt.edu:80/ETD/available/etd-06252003-144932/, etd-06252003-144932 |
| Date Deposited: |
10 Nov 2011 19:48 |
| Last Modified: |
15 Nov 2016 13:45 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/8189 |
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