Robert A. Ware

Catalytic hydrodemetallation of petroleum

Publisher Summary This chapter discusses the elements of physical chemistry, heterogeneous catalysis, and reaction engineering that are necessary for a basic understanding of catalytic hydrodemetallation. It focuses on vanadium and nickel removal because these are the most abundant metals in petroleum. Following this, it discusses the nature of the metal compounds in petroleum oils and the targeted reactants. The chemical composition of the host petroleum and residuum is described, including a discussion of the two classes of metal compounds: (1) metalloporphyrins and (2) nonporphyrin metals. A comparison between the characteristics of vanadium and nickel complexes and their distribution in residua is also presented. Commercial residuum hydroprocessing technology is then discussed to establish the role and requirements of hydroprocessing in the overall refinery residuum conversion scheme. Finally, the kinetics and mechanisms of catalytic HDM reactions are presented and future perspectives for the study of residuum hydroprocessing and the rational design of hydrodemetallation catalysts and processes are highlighted.

High Temperature Sensitivity of Paraffin Hydrocracking

Publisher Summary A viable route toward meeting the increased demand for clean diesel fuels is the conventional hydroprocessing of waxy feeds, such as those found along the Pacific Rim or, in the extreme, those produced from the Fischer–Tropsch technology. In addition to having an extremely high cetane number (> 70), the diesel fuel produced via this route is low in both aromatics and sulfur. An important consideration in the design of a commercial reactor for such operation is the apparent activation energy, E app , of the dominant heat-release reaction, which is cracking. Studies have shown that the value of E app for n-paraffin hydrocracking in the presence of basic-nitrogen poisons can be unusually high, being on the order of 200 kcal/gmole. Such a high E app has significant implications for the control of commercial reactors. The chapter presents a simplified model development for n-paraffin cracking that explains the way by which such poisoned reaction pathways can lead to such high E app values.