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Title: An Ab Initio Approach Towards Engineering Fischer-Tropsch Surface Chemistry

Abstract

As the US seeks to develop an energy strategy that reduces the reliance on foreign oil, there is a renewed interest in research and development of the Fischer Tropsch synthesis of converting syngas into long chain hydrocarbon products. This report investigates some of the basic elementary steps for Fischer-Tropsch synthesis over ideal Co and Ru metal surfaces by using ab initio density functional theoretical calculations. This includes activation of CO of CO, the hydrogenation of CH{sub x} intermediates, and the adsorption and dissociation of water. The activation of CO is studied in detail showing a strong dependence on the surface coverage, defect sites and Co-Ru alloy formation. The barriers for CO activation over the ideal (0001) surfaces are quite high making CO activation at the terrace sites unlikely under operating conditions. The calculations for the overall reaction energies at the step edges indicate that these sites are much more reactive. The hydrogenation of the CHx intermediates occurs in a sequential fashion. CH1 was found to be the most stable intermediate over various surfaces. The barriers to form both CH* as well as CH{sub 4} are both found to be highly activated and potentially difficult steps. Water which is a reactionmore » product was found to be weakly adsorbed on Co. Analysis of the microscopic reverse reaction of water activation indicates that this process has a very low activation barrier. Consequently, any water which forms desorbs or is activated to form surface hydroxyl intermediates.« less

Authors:
Publication Date:
Research Org.:
University Of Virginia
Sponsoring Org.:
USDOE
OSTI Identifier:
909653
DOE Contract Number:  
FG26-01NT41275
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
01 COAL, LIGNITE, AND PEAT; ADSORPTION; ALLOYS; CHAINS; CHEMISTRY; DEFECTS; DISSOCIATION; FISCHER-TROPSCH SYNTHESIS; FUNCTIONALS; HYDROCARBONS; HYDROGENATION; WATER

Citation Formats

Neurock, Matthew. An Ab Initio Approach Towards Engineering Fischer-Tropsch Surface Chemistry. United States: N. p., 2002. Web. doi:10.2172/909653.
Neurock, Matthew. An Ab Initio Approach Towards Engineering Fischer-Tropsch Surface Chemistry. United States. https://doi.org/10.2172/909653
Neurock, Matthew. Wed . "An Ab Initio Approach Towards Engineering Fischer-Tropsch Surface Chemistry". United States. https://doi.org/10.2172/909653. https://www.osti.gov/servlets/purl/909653.
@article{osti_909653,
title = {An Ab Initio Approach Towards Engineering Fischer-Tropsch Surface Chemistry},
author = {Neurock, Matthew},
abstractNote = {As the US seeks to develop an energy strategy that reduces the reliance on foreign oil, there is a renewed interest in research and development of the Fischer Tropsch synthesis of converting syngas into long chain hydrocarbon products. This report investigates some of the basic elementary steps for Fischer-Tropsch synthesis over ideal Co and Ru metal surfaces by using ab initio density functional theoretical calculations. This includes activation of CO of CO, the hydrogenation of CH{sub x} intermediates, and the adsorption and dissociation of water. The activation of CO is studied in detail showing a strong dependence on the surface coverage, defect sites and Co-Ru alloy formation. The barriers for CO activation over the ideal (0001) surfaces are quite high making CO activation at the terrace sites unlikely under operating conditions. The calculations for the overall reaction energies at the step edges indicate that these sites are much more reactive. The hydrogenation of the CHx intermediates occurs in a sequential fashion. CH1 was found to be the most stable intermediate over various surfaces. The barriers to form both CH* as well as CH{sub 4} are both found to be highly activated and potentially difficult steps. Water which is a reaction product was found to be weakly adsorbed on Co. Analysis of the microscopic reverse reaction of water activation indicates that this process has a very low activation barrier. Consequently, any water which forms desorbs or is activated to form surface hydroxyl intermediates.},
doi = {10.2172/909653},
url = {https://www.osti.gov/biblio/909653}, journal = {},
number = ,
volume = ,
place = {United States},
year = {2002},
month = {9}
}