Please use this identifier to cite or link to this item: http://scholarbank.nus.edu.sg/handle/10635/90546
Title: First principle reaction path analysis of the Fischer-Tropsch synthesis mechanism. Effect of CO coverage on the kinetics of the CO insertion mechanism
Authors: Zhuo, M.
Saeys, M. 
Issue Date: 2011
Source: Zhuo, M.,Saeys, M. (2011). First principle reaction path analysis of the Fischer-Tropsch synthesis mechanism. Effect of CO coverage on the kinetics of the CO insertion mechanism. 11AIChE - 2011 AIChE Annual Meeting, Conference Proceedings : -. ScholarBank@NUS Repository.
Abstract: Fischer-Tropsch Synthesis (FTS), the conversion of CO and H 2 to long chain hydrocarbons, (CH 2) n, and H 2O, involves a sequence of C-O scission, C-C forming, and C and O hydrogenation steps. Different reaction sequences have been proposed. Recent Density Functional Theory (DFT) calculations provide theoretical support for the CO insertion mechanism, where C-C bond formation via a RCH + CO step occurs before C-O scission. Subsequent surface science experiments confirmed that C-O bond breaking is indeed kinetically possible on Co(0001) terraces if a C xH y-O moiety can be formed, as proposed in the CO insertion mechanism. However, on a clean Co(0001) surface the calculated CO turnover frequency (TOF) for the CO insertion mechanism is several orders of magnitude lower than experimental values. FTS is performed under a CO partial pressure of about 7 bar. First principle phase diagram calculations indicate that the CO coverage exceeds 1/3 ML under such conditions, in agreement with experimental data. DFT calculations on a CO pre-covered Co(0001) surface further show that the binding energies of the various reaction intermediates decrease by about 10 kJ/mol in the presence of 1/3 ML CO, and the overall reaction energy for the CO insertion mechanism changes from +42 kJ/mol endothermic on a clean surface to -40 kJ/mol exothermic on the CO pre-covered surface. A kinetic analysis using the first principle data furthermore shows that the CO TOF increases from 10 -8 s -1 to 0.1 s -1 when the high CO coverage is accounted for.
Source Title: 11AIChE - 2011 AIChE Annual Meeting, Conference Proceedings
URI: http://scholarbank.nus.edu.sg/handle/10635/90546
ISBN: 9780816910700
Appears in Collections:Staff Publications

Show full item record
Files in This Item:
There are no files associated with this item.

Page view(s)

32
checked on Feb 17, 2018

Google ScholarTM

Check


Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.