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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 the research and development of the Fischer Tropsch synthesis for converting syngas into long chain hydrocarbon products. This report investigates some of the basic elementary steps for Fischer-Tropsch synthesis over ideal Pt, Ru and carbon-covered Pt and Ru metal surfaces by using ab initio density functional theoretical calculations. We examine in detail the adsorption sites as well as the binding energies for C, CH, CH{sub 2}, CH3 and CH4 on Pt(111), Ru(0001), 2x2-C-Pt(111) and 2x2-C-Ru(0001). The results indicate that the binding energies increase with decreasing the hydrogen in the fragment molecule, i.e. CH{sub 4} < CH{sub 3} < CH{sub 2} < CH < C. More specifically the work analyzes the elementary steps involved in the activation of methane. This is simply the reverse set of steps necessary for the hydrogenation of C to CH{sub 4}. The results indicate that these hydrocarbon intermediates bind more strongly to Ru than Pt. The introduction of co-adsorbed carbon atoms onto both Ru(0001) as well as Pt(111) significantly increased the overall energies as well as the activation barriers for C-H bond activation. Themore » results suggest that Ru may be so active that it initially can initially activate CH4 into CH or C but ultimately it dies because the CH and C intermediates poison the surface and thus kill its activity. Methane can dissociate on Pt but subsequent hydrocarbon coupling reactions act to remove the surface carbon.« less

Authors:
;
Publication Date:
Research Org.:
University Of Virginia
Sponsoring Org.:
USDOE
OSTI Identifier:
909654
DOE Contract Number:  
FG26-01NT41275
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
01 COAL, LIGNITE, AND PEAT; 03 NATURAL GAS; 08 HYDROGEN; ADSORPTION; ATOMS; CARBON; CHAINS; CHEMISTRY; FISCHER-TROPSCH SYNTHESIS; FUNCTIONALS; HYDROCARBONS; HYDROGEN; HYDROGENATION; METHANE

Citation Formats

Neurock, Matthew, and Chopra, Siddharth. An Ab Initio Approach Towards Engineering Fischer-Tropsch Surface Chemistry. United States: N. p., 2003. Web. doi:10.2172/909654.
Neurock, Matthew, & Chopra, Siddharth. An Ab Initio Approach Towards Engineering Fischer-Tropsch Surface Chemistry. United States. https://doi.org/10.2172/909654
Neurock, Matthew, and Chopra, Siddharth. Thu . "An Ab Initio Approach Towards Engineering Fischer-Tropsch Surface Chemistry". United States. https://doi.org/10.2172/909654. https://www.osti.gov/servlets/purl/909654.
@article{osti_909654,
title = {An Ab Initio Approach Towards Engineering Fischer-Tropsch Surface Chemistry},
author = {Neurock, Matthew and Chopra, Siddharth},
abstractNote = {As the US seeks to develop an energy strategy that reduces the reliance on foreign oil, there is a renewed interest in the research and development of the Fischer Tropsch synthesis for converting syngas into long chain hydrocarbon products. This report investigates some of the basic elementary steps for Fischer-Tropsch synthesis over ideal Pt, Ru and carbon-covered Pt and Ru metal surfaces by using ab initio density functional theoretical calculations. We examine in detail the adsorption sites as well as the binding energies for C, CH, CH{sub 2}, CH3 and CH4 on Pt(111), Ru(0001), 2x2-C-Pt(111) and 2x2-C-Ru(0001). The results indicate that the binding energies increase with decreasing the hydrogen in the fragment molecule, i.e. CH{sub 4} < CH{sub 3} < CH{sub 2} < CH < C. More specifically the work analyzes the elementary steps involved in the activation of methane. This is simply the reverse set of steps necessary for the hydrogenation of C to CH{sub 4}. The results indicate that these hydrocarbon intermediates bind more strongly to Ru than Pt. The introduction of co-adsorbed carbon atoms onto both Ru(0001) as well as Pt(111) significantly increased the overall energies as well as the activation barriers for C-H bond activation. The results suggest that Ru may be so active that it initially can initially activate CH4 into CH or C but ultimately it dies because the CH and C intermediates poison the surface and thus kill its activity. Methane can dissociate on Pt but subsequent hydrocarbon coupling reactions act to remove the surface carbon.},
doi = {10.2172/909654},
url = {https://www.osti.gov/biblio/909654}, journal = {},
number = ,
volume = ,
place = {United States},
year = {2003},
month = {9}
}