Recent advances in the science and technology of ultra low sulfur diesel (ULSD) production

Sulfur content of diesel fuel has been cut down to ultra low levels by environmental regulation in many countries with the aim of reducing diesel engine's harmful emissions and improving air quality. As a result, research on the production of ultra low sulfur diesel (ULSD) has gained enormous interest in the scientific community worldwide. The renewed interest in ULSD research is driven by the need, to have a comprehensive understanding of the various factors influencing deep desulfurization of diesel to the ultra low level as well as to find cost-effective ways for ULSD production. This review discusses the recent advancement on ULSD production from both scientific and applied point of view. The key fundamentals and the factors influencing the removal of the least reactive sterically hindered sulfur species from diesel feedstocks are reviewed and discussed in detail. Latest development in deep HDS catalyst and the scientific basis for the improvements in the activity of the new generation HDS catalyst are presented. Advancement in the deep HDS process technologies is reviewed and various options available for revamping and modifying the existing low sulfur diesel HDS units for ULSD production are described highlighting the importance of catalyst selection and hydrogen consumption issues. Special attention has been paid to the progress in the alternative (non-hydrogenation) process concepts and technologies that are being developed for ULSD production. (C) 2010 Elsevier B.V. All rights reserved.