TABLE OF CONTENTS The kinetics of hydroprocessing reactions are usually based on the extensive evaluations of the feeds and products. For example, the compositional changes with TOS were followed under variable experimental conditions such as temperature, pressure and LHSV. In the case of kinetics of catalyst deactivation, focus has been on the structural changes incurred by catalyst surface caused by the deposition of coke and metals as well as other factors. For the asphaltenes and metals containing feeds, the kinetics of catalyst deactivation were based on the total amount of coke and metals deposited on the catalyst surface in the course of experiments. These parameters were then related to the decline in catalyst activity for hydroprocessing reactions. The advancements in analytical techniques may allow the detailed characterization and quantification of hydrocarbon types and groups present in heavy feed, as well as in the coke formed on catalyst surface during hydroprocessing. With such information available, the effect of various structural parameters of coke precursors in the feed on kinetics of the deposit formation can be elucidated in more detail.
The structure of coke precursors in VGO and HGO differs markedly from those in the heavy feeds containing asphaltenes and metals. For the former feeds, polycondensed aromatics and N-bases may be the main cause of the coke deposit formation. To a lesser extent, poisoning by N-bases is also present for the metals and asphaltenes containing feeds. For these feeds, the adverse effect of N-bases on catalyst activity is expected to...
