This dissertation, "Catalytic Methane Reformation and Aromatization Reaction Studies via Cavity Ringdown Spectroscopy and Time of Flight Mass Spectrometry" by Ling, Li, 李凌, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Abstract of thesis entitled CATALYTIC METHANE REFORMATION AND AROMATIZATION REACTION STUDIES VIA CAVITY RINGDOWN SPECTROSCOPY AND TIME OF FLIGHT MASS SPECTROMETRY Submitted by Li Ling for the degree of Doctor of Philosophy at The University of Hong Kong in November 2007 This thesis reports studies of catalytic reaction of CH /CO reforming and also 4 2 CH aromatization using the techniques of cavity ringdown spectroscopy (CRDS), continuous wave cavity enhanced absorption spectroscopy (CEAS) and time of flight mass spectrometry (TOF-MS). The important associated reverse water-gas shift (RWGS) reaction over La NiO catalyst during CH /CO reforming has been studied by CEAS. 2 4 4 2 Our results indicated that the RWGS reaction promoted the conversion of CO and decreased the partial pressure of hydrogen. Reaction intermediates in CH /CO reforming 4 2 such as CHO, OH and CH were observed by means of the liquid-N quenching 3 2 technique, and the reaction step: CH + [O] = CH O was primarily confirmed. During x x the CH /CO reforming reaction carbon deposition was severe, which caused the 4 2 deactivation of the catalysts. The high-resolution transmission electron microscopy (HRTEM) images of the catalysts indicated that the formation of nanotubes and graphite carbon covered the active sites of catalysts. CH /CO reforming over La NiO and 4 2 2 4 10%NiO/CeO -La O catalysts was studied via direct monitoring of the reactants and 2 2 3 products using CRDS. Vibration-rotational absorption lines of CH, H O, CO and CO 4 2 2 molecules were recorded in the near infrared spectral region for in situ monitoring the reaction. Our results showed that La NiO was significantly superior to 2 4 10%NiO/CeO -La O for promoting the CH /CO reforming reaction. 2 2 3 4 2 Methane dehydroaromatization reaction over the Mo/HZSM-5 catalyst was investigated via direct monitoring of the reactants and products using TOF-MS. The effect of reaction temperature, time on stream and pulsed laser energy on the distribution of products were studied. Our results showed that methane conversion under the condition of pulsed expansion was estimated to be about one third and the major product formed was naphthalene, which is different from earlier observation over the same catalyst when the reaction was carried out at atmospheric pressure. The formation of reaction intermediate, CHO, in methane dehydroaromatization was detected and a reaction mechanism for methane dehydroaromatization under the pulsed expansion condition was proposed. As hydrogen is important for fuel cell application, our results indicated that under the pulsed expansion condition with the production of naphthalene, methane dehydroaromatization is more favorable for the production of hydrogen from methane. DOI: 10.5353/th_b3970740 Subjects: MethaneCatalytic reformingCavity-ringdown spectroscopyIon mobility spectroscopy