Speight, R. J. (Richard J.), Rourke, Jonathan, Wong, A., Barrow, Nathan S., Ellis, P. R., Bishop, P. T. and Smith, Mark E. (2011) 1H and 13C solution- and solid-state NMR investigation into wax products from the Fischer-Tropsch process. Solid State Nuclear Magnetic Resonance, Vol.39 (No.3-4). pp. 58-64. doi:10.1016/j.ssnmr.2011.03.008

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Abstract

(1)H and (13)C solid- and solution-state NMR have been used to characterise waxes produced in the Fischer-Tropsch reaction, using Co-based catalysts either unpromoted or promoted with approximately 1 wt% of either cerium or rhenium. The aim was to measure average structural information at the submolecular level of the hydrocarbon waxes produced, along with identification of the minor products, such as oxygenates and olefins, which are typically observed in these waxes. A parameter of key interest is the average number of carbon atoms within the hydrocarbon chain (N(C)). A wax prepared using an unpromoted Co/Al(2)O(3) catalyst had N(C)similar to 20, whilst waxes made using rhenium- or cerium-promoted Co/Al(2)O(3) catalysts were found to have N(C)similar to 21. All three samples contained small amounts of oxygenates and alkenes. The subtle differences found in the waxes, in particular the minor species produced, demonstrate that the different promoters have different effects during the reaction, with the Re-promoted catalyst producing the fewest by-products. It is shown in (13)C solid-state NMR spectra that for that for longer chain (compared to the lengths of chain in previous studies) waxes that the lack of resolution and the complexities added by the differential cross-polarisation (CP) dynamics mean that it is difficult to accurately determine N(C) from this approach. However the N(C) determined by (13)C CP magic angle spinning NMR is broadly consistent with the more accurate solution approaches used and suggest that the wax characteristics do not change in solution. On this basis an alternative approach for determining N(C) is suggested based on (1)H solution state NMR that provides a higher degree of accuracy of the chain length as well as information on the minor constituents.

Item Type:	Journal Article
Subjects:	Q Science > QD Chemistry
Divisions:	Administration > University Executive Office Faculty of Science, Engineering and Medicine > Science > Chemistry Faculty of Science, Engineering and Medicine > Science > Physics
Library of Congress Subject Headings (LCSH):	Nuclear magnetic resonance, Waxes -- Analysis, Fischer-Tropsch process
Journal or Publication Title:	Solid State Nuclear Magnetic Resonance
Publisher:	Academic Press
ISSN:	0926-2040
Official Date:	May 2011
Dates:	Date Event May 2011 Published
Volume:	Vol.39
Number:	No.3-4
Page Range:	pp. 58-64
DOI:	10.1016/j.ssnmr.2011.03.008
Status:	Peer Reviewed
Publication Status:	Published
Access rights to Published version:	Restricted or Subscription Access
Funder:	Engineering and Physical Sciences Research Council (EPSRC), Johnson Matthey Plc., Biotechnology and Biological Sciences Research Council (Great Britain) (BBSRC), Natural Sciences and Engineering Research Council of Canada (NSERC), University of Warwick, Great Britain
Grant number:	007293 (KTP)

Data sourced from Thomson Reuters' Web of Knowledge

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