The fields of hydrodesulfurization (HDS) and hydrodenitrogenation (HDN) continue to attract the attention of researchers in the various disciplines connected to these fascinating problems that represent two of the key outstanding chemical challenges for the petroleum refining industry in view of their very strong environmental and commercial implications. One area that has flourished impressively over the last 15 years is the organometallic chemistry of thiophenes and other related sulfur-containing molecules. This has become a powerful method for modeling numerous surface species and reactions implicated in HDS schemes, and nowadays it represents an attractive complement to the standard procedures of surface chemistry and heterogeneous catalysis, for understanding the complex reaction mechanisms involved in this process. Similar developments have begun to appear in connection with HDN mechanisms, although in a much more modest scale and depth. Some years ago when, encouraged by Prof. B. R. James, this book was planned, several excellent reviews and monographs treating different aspects of HDS were already available including some on the subject of organometallic models. However, it seemed appropriate to try to summarize the most striking features of this chemistry in an updated and systematic way, and inasmuch as possible in connection with the common knowledge and beliefs of the mechanisms of heterogeneous HDS catalysis. Hopefully, this attempt to build some conceptual bridges between these two traditionally separated areas of chemistry has met with some success.
The hydrodesulfurization and hydrodenitrogenation of petroleum and refinery cuts have been in continuous development and in industrial practice for several decades. New environmental constraints regarding the quality of fuels has produced a renaissance of this field as the search for novel solution to this problem intensifies. This volume reviews the structures, bonding and reactions of metal complexes of the thiophenes and other HDS-related molecules, as well as of some HDN-related organinitrogen compounds. This chemistry is analyzed in the context of modeling some key species and reactions implicated in HDS and HDN catalysis. Many parallels are drawn between organometallic and surface chemistry, and homogeneous and heterogeneous catalysis. The book should be of value to chemists and chemical engineers in academic and industrial environments, since the organometallic modeling approach emerges as a powerful tool to aid in the understanding of the structures and reaction mechanisms occurring in real systems, and in the design of novel HDS and HDN catalysts.