Elucidating the effects of catalyst parameters on metal and acid catalysts using isotopic transient kinetic analysis

With much interest in “combinatorial catalysis”, the chemical industry appears to be driven by high throughput screening of catalysts with complex composition. Then, it appears that the fundamental understanding about the impact the promoters have on the surface reaction is more critical in today's catalyst development research then ever before. The traditional ex situ characterization techniques alone do not provide information about the active surface species or the active sites. Often, these techniques provide information about adsorbed species which are mostly spectators. Use of an in situ characterization technique called steady-state isotopic transient kinetic analysis, in conjunction with the traditional characterization techniques, was use to study the impact of catalyst composition and reaction conditions on the kinetic parameters of active surface intermediates on solid catalysts.; The first portion of this thesis discusses the role of zeolitic support acidity on Pd catalyzed reaction of methanol synthesis. The acidity of zeolite Y was varied using its ion exchange capability. The results indicated that the support acidity influences CO hydrogenation activity of PdY catalysts. It appears that the potential changes in the electron density of Pd due to the presence of acid sites may have the strongest contribution on the CO hydrogenation activity of the PdY catalyst.; The remainder of the thesis focuses on understanding n-butane isomerization on sulfated zirconia (SZ)-based catalysts. Unlike other solid acid catalysts (such as acidic zeolites), SZ exhibits exceptionally high activity and selectivity for n-butane isomerization, even at room temperature. The presented study focuses on some of the most important issues such as (a) the reaction mechanism, (b) the deactivation mechanism, and the role of promoters such as (c) Pt and H₂, and (d) Al₂O₃ . The changes in the concentration and the average surface residence time of active intermediates were also utilized to address heterogeneity of active sites and their relationship to acid site measurements.