Chapter 1 - Introduction

Abstract

There are several types of commercial processes being developed for upgrading various petroleum feeds. They involve either hydrogen addition to the feed or carbon rejection from the feed. The hydrogen addition processes require the presence of an active catalyst. For catalytic processes, it is more difficult to upgrade vacuum residues than atmospheric residues, whereas far fewer problems are experienced with catalytic upgrading of vacuum gas oil, heavy gas oil, and deasphalted oil. Decades of refinery experience confirmed that the atmospheric distillates can be upgraded without any difficulties. Compared with thermal processes, hydroprocessing operations are more flexible, giving higher yields of liquid fractions. However, the costs of high-pressure equipment, catalyst inventory, and H2 required for hydroprocessing have to be offset by the increased yields and quality of liquid products. This chapter provides an introduction to spent hydroprocessing catalysts. The market demand for hydroprocessing catalysts was estimated to increase with an annual growth rate of 4.4%. About half of this amount is used for hydroprocessing of distillates to produce clean fuels, whereas the other half is used for residue upgrading. Some of the reasons for significant increase in the production of spent hydroprocessing catalysts in recent years are: a rapid growth in the distillates hydrotreating capacity to meet the increasing demand for ultra-low sulfur transportation fuels; and reduced cycle times due to higher severity operations in diesel hydrotreating units to meet stringent fuels specifications. In addition, disposal of spent catalysts requires compliance with stringent environmental regulations. Spent hydroprocessing catalysts are classified as hazardous wastes by the environmental protection agency in the USA. This chapter also provides an overview of the book, Handbook of Spent Hydroprocessing Catalysts, the focus of which is on all aspects of spent hydroprocessing catalysts.