The application of inelastic neutron scattering to investigate methane reforming catalysts

McFarlane, Andrew Robert (2012) The application of inelastic neutron scattering to investigate methane reforming catalysts. PhD thesis, University of Glasgow.

Abstract

Hydrocarbonaceous overlayers formed on a range of nickel alumina and gold-doped nickel alumina catalysts during both the H2O and CO2 reforming of methane has been examined using a number of techniques including thermal studies, XRD, TEM IR and Raman spectroscopy. These techniques have allowed both qualitative and quantitative analysis of the carbon and hydrogen components of coke to be achieved. Both amorphous carbon and filamentous carbon has been observed. Results show that changing the catalyst preparation routine effects the morphology of the carbon in both the CO2 and H2O reforming reactions. The “dry” and steam reforming reactions were also studied by inelastic neutron scattering. This technique has permitted quantitative measurements of the extent of hydrogen retention for the first time and has allowed elementary steps associated with the reaction to be explored from a new perspective.
As well as determining the nature and quantity of the hydrocarbonaceous overlayers, the source of the coke has also been considered in the CO2 reforming reaction. Isotopic substitution reactions have been employed to achieve this. Temperature programmed oxidation measurements using a 13CO2 feedstream identify a clear role for the oxidant in the carbon retention process.

The combination of techniques outlined above has permitted a series of elementary reactions to be proposed for both reforming reactions. Elementary surface reactions involving hydrogen are shown to be fast and efficient compared to those involving carbon. Furthermore, oxidation of carbon to CO is slower than that of carbon polymerisation. These statements are true for both CO2 and H2O reforming and suggest the CO2 reforming reaction has the potential to represent a environmentally friendly alternative to the industrially preferred steam reforming process.

As well as increasing the understanding of these two highly relevant reaction systems, a range of inelastic neutron scattering reactors have been designed, built and tested under reforming conditions in order to accomplish the quantitative hydrogen measurements. An evaluation of these reactors, as well as a description of the development of the INS technique as a quantitative tool is given.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Keywords: Catalysis, methane reforming, spectroscopy, inelastic neutron scattering, coke, hydrogen quantification, isotopes
• Subjects: Q Science > QD Chemistry
• Colleges/Schools: College of Science and Engineering > School of Chemistry
• Supervisor's Name: Lennon, Dr. David
• Date of Award: 2012
• Depositing User: Mr Andrew R McFarlane
• Unique ID: glathesis:2012-4098
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 14 Mar 2013 16:20
• Last Modified: 14 Mar 2013 16:22
• URI: https://theses.gla.ac.uk/id/eprint/4098