Stephen S. Wong

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.