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Toward an Understanding of Methane Selectivity in the Fischer-Tröpsch Process

Psarras, Peter Campbell
http://rave.ohiolink.edu/etdc/view?acc_num=csu1407953187

Abstract Details

2014, Doctor of Philosophy in Clinical-Bioanalytical Chemistry, Cleveland State University, College of Sciences and Health Professions.
The purpose of this research is to elucidate a better understanding of the conditions relevant to methane selectivity in the Fischer-Tröpsch (FT) process. The development of more efficient FT catalysts can result in great commercial profit. The industrially relevant FT process has long been hampered by the production of methane. Nearly 60 percent of FT capital is devoted to the removal of methane and purification of feed-stock gases through steam-reforming. Naturally, a more efficient FT catalyst would need to have a reasonable balance between catalytic activity and suppression of methane formation (low methane selectivity). Though a significant amount of work has been devoted to understanding the mechanisms involved in methane selectivity, the exact mechanism is still not well understood. Density functional theory (DFT) methods provide an opportunity to explore the FT catalytic process at the molecular level. This work represents a combination of various DFT approaches in an attempt to gather new insight on the conditions relevant to methane selectivity. A thorough understanding of the electronic environment involved in the surface-adsorbate interaction is necessary to the advancement of more efficient Fischer-Tröpsch catalysts. This study investigates the promotive effect of four late transition metals (Cu, Ag, Au and Pd) on three FT catalytic surfaces (Fe, Co and Ni). The purpose of this research is to examine the surface-adsorbate interaction from two perspectives: 1) interactions occurring between FT precursors and small, bimetallic surface analogs (clusters), and 2) plane-wave calculations of the interactions between FT precursors and simulated bulk surfaces. Our results suggest that promising candidates for the reduction of FT methane selectivity include Au and Pd on Ni, Au and Ag on Co, and Cu, Ag, and Pd on Fe. Additionally, cluster models were susceptible to effects not encountered in the plane-wave approach. Thermodynamic trends can be made more transferable through the following adjustments to the cluster model: matching of bulk-like atomic geometries and spacings, extension of the cluster to include one sub-layer, and the minimization of intra-cluster dipoles.
David Ball, PhD (Advisor)
Aloysius Hepp, PhD (Committee Member)
Miron Kaufman, PhD (Committee Member)
John Turner, PhD (Committee Member)
269 p.
Materials Science; Physical Chemistry

Recommended Citations

Citations

  • Psarras, P. C. (2014). Toward an Understanding of Methane Selectivity in the Fischer-Tröpsch Process [Doctoral dissertation, Cleveland State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=csu1407953187

    APA Style (7th edition)

  • Psarras, Peter. Toward an Understanding of Methane Selectivity in the Fischer-Tröpsch Process. 2014. Cleveland State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=csu1407953187.

    MLA Style (8th edition)

  • Psarras, Peter. "Toward an Understanding of Methane Selectivity in the Fischer-Tröpsch Process." Doctoral dissertation, Cleveland State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=csu1407953187

    Chicago Manual of Style (17th edition)

csu1407953187
231
© 2014, all rights reserved.
This open access ETD is published by Cleveland State University and OhioLINK.