Catalyst and process technologies for ultra low sulfur diesel

The production of clean diesel by hydrotreating and deep hydrodesulfurizati on (HDS) has attracted increased attention recently due to the introduction of new environmental legislation regarding fuel specifications. In order t o meet the specifications there is a need to modify and improve existing re actors and processes and to introduce more active and selective catalysts. The removal of sterically hindered sulfur-containing molecules is observed to be a key issue for deep HDS. Also the choice of operation conditions and reactor internals play an important role for deep HDS. The present article will focus on key hydrotreating options available to obtain ultra low sulf ur diesel levels and some of the theoretical and experimental structure-act ivity relationships which may aid catalyst developments. (C) 1999 Elsevier Science B.V. All rights reserved.