Deactivation of a 0.53 wt% Pt/γ-Al<sub>2</sub>O<sub>3</sub> catalyst due to strongly adsorbed carbonaceous residue was investigated. The role of the carbonaceous residue formed during hydrocarbon conversion reactions of 1-octene, toluene and 1:1 volume mixture of 1-octene/toluene at 300, 400 and 450°C was established and a model developed to account for the activity and selectivity changes at the very start of the reaction, just as the hydrocarbon residue begins to form on the surface of the catalyst. CO pulse chemisorption was used to determine the extent of Pt surface blocked by the hydrocarbon residue by titrating the Pt sites that remained exposed. The efficiency of catalyst regeneration with H<sub>2</sub> at 400°C was investigated and hydrocarbon reactions were performed on the regenerated catalyst to assess the catalytic activity and selectivity on a Pt surface covered with carbonaceous residue. Characterisation of the carbonaceous residue deposited on the catalyst during hydrocarbon conversion reactions was carried out using TPO, TGA-MS and Raman microspectroscopy. The amount, composition, reactivity and chemical structure of the carbonaceous residue in relation to reaction time and temperature was investigated. Increasing the reaction temperature accelerated the formation of coke. The H:C ratio of the carbonaceous residue played an important role in the selectivity of the hydrocarbon reaction. In addition, two batches of the 0.53 wt% Pt/γ-Al<sub>2</sub>O<sub>3</sub> catalyst spent six months in an industrial Pyrolysis gasoline (Pygas) Hydrotreatment reactor. The catalyst batches were strategically placed at the inlet and outlet of the reactor. Raman microspectroscopy revealed that the coke accumulated on the individually coked samples consisted of a mixture of disordered and ordered pre-graphitic polycrystalline coke. The reactivity and type of the coke varied between the samples placed near the inlet or the outlet of the industrial reactor.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:521157 |
| Date | January 2009 |
| Creators | Arteaga Colina, Geomar Daniel |
| Publisher | University of Aberdeen |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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