Graduate Thesis Or Dissertation

 

Density Functional Theory Investigation of CH Coupling and CH Hydrogenation Reactions on Different Cobalt Surface Facets and Fischer-Tropsch Temperature Swing Reactor Optimization Public Deposited

Downloadable Content

Download PDF
https://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/d504rp11r

Descriptions

Attribute NameValues
Creator
Abstract
  • Fischer-Tropsh Synthesis is a chemical process that converts CO and H₂ (syngas) into long stable hydrocarbon chains to use as fuel. This process suffers from large product distribution that requires expensive post processing. In this study, the reaction mechanism of hydrocarbon chain growth on Co is investigated on different surface facets of Co in order to study their effects on the rate-limiting reaction steps. Fischer-Tropsch is a complex multi-step process so a microkinetic model for the carbide chain growth mechanism, available literature data, and the degree of rate control analysis was used to determine the rate-limiting steps for hydrocarbon chain production, CO utilization, and minimization of CH₄ production. The CH-CH carbon coupling and CH hydrogenation were determined to be the critical steps in chain growth, CH₄ formation, and CO utilization based on the degree of rate control analysis of the microkinetic model. Density Functional Theory (DFT) was used to investigate these reaction steps on cobalt catalyst to understand how different surface facets affect these reaction steps. The calculated energy landscape, reaction and activation energies for the two reaction paths are initially compared on two different Co facets ((001) and (110)) and used to determine the most effective surface structure for CH-CH carbon coupling, which leads to chain growth, and the least effective surface structure for CH hydrogenation, which leads to CH₄ formation. Other surface facets under investigation include (111) and (101). The forward activation barrier for the CH coupling reaction showed little sensitivity to cobalt surface structure (ΔE₀₀₁,[subscript F] = 1.01 eV, ΔE₀₁₁,[subscript F] = 1.08 eV) as opposed to the CH hydrogenation reaction where forward activation barriers ranged between 0.29 eV and 0.96 eV on the (001) and (101) facets respectively. This study is a part of a larger initiative to design and optimize a FTS micro-reactor for commercial use which combines atomistic DFT calculations, multiphysics modeling (mass, heat and fluid transport), experimental catalyst design, and micro-reactor design.
License
Resource Type
Date Issued
Degree Level
Degree Name
Degree Field
Degree Grantor
Commencement Year
Advisor
Committee Member
Academic Affiliation
Non-Academic Affiliation
Subject
Rights Statement
Publisher
Peer Reviewed
Language
Replaces
Additional Information
  • description.provenance : Submitted by Dennis Petersen (peterden@oregonstate.edu) on 2016-03-14T06:15:07ZNo. of bitstreams: 1PetersenDennisF2016.pdf: 3592442 bytes, checksum: 1baaef686d8d02b5fc4488d1d17ade2b (MD5)
  • description.provenance : Approved for entry into archive by Laura Wilson(laura.wilson@oregonstate.edu) on 2016-03-15T17:17:38Z (GMT) No. of bitstreams: 1PetersenDennisF2016.pdf: 3592442 bytes, checksum: 1baaef686d8d02b5fc4488d1d17ade2b (MD5)
  • description.provenance : Submitted by Dennis Petersen (peterden@oregonstate.edu) on 2016-03-08T22:04:47ZNo. of bitstreams: 1PetersenDennisF2016.pdf: 4390562 bytes, checksum: e193102bc557fdec16937f743061c98b (MD5)
  • description.provenance : Made available in DSpace on 2016-03-15T17:17:38Z (GMT). No. of bitstreams: 1PetersenDennisF2016.pdf: 3592442 bytes, checksum: 1baaef686d8d02b5fc4488d1d17ade2b (MD5) Previous issue date: 2016-03-03
  • description.provenance : Rejected by Julie Kurtz(julie.kurtz@oregonstate.edu), reason: Rejecting to remove the page numbers from the pretext pages, which has caused the introduction to start on page 14 but should start on page 1. After revised, move the page numbers in the actual thesis to the top right corner.Everything else looks good. once revised, log back into ScholarsArchive and go to the upload page. Replace the attached file with the revised file and resubmit.Thanks,Julie on 2016-03-11T22:41:41Z (GMT)
  • description.provenance : Approved for entry into archive by Julie Kurtz(julie.kurtz@oregonstate.edu) on 2016-03-14T16:05:08Z (GMT) No. of bitstreams: 1PetersenDennisF2016.pdf: 3592442 bytes, checksum: 1baaef686d8d02b5fc4488d1d17ade2b (MD5)
Embargo date range
  • 2017-08-14 to 2018-03-14

Relationships

Parents:

This work has no parents.

In Collection:

Items