The development of efficient catalysts for hydrodesulfurization (HDS) and hydrodenitrogenation (HDN) processes is an essential and urgent research field. During oil refinement the removal of sulfur and nitrogen compounds from petroleum feedstock is crucial, as the emission of sulfur and nitrogen oxides into the atmosphere causes severe environmental problems. In light of the industrial process for hydrocarbons, HDS is indispensable as it eliminates the poisoning of catalysts during hydrotreatment and hydrocracking. In order to develop new catalysts, the mechanism of these reactions as well as the structures and functions of the catalysts need to be elucidated. This book provides an up-to-date and deep insight, which spans kinetic studies, catalytic cycles, structures and properties of catalysts to process engineering. Therefore every chemist and engineer working in this important research field will welcome this valuable source of information.

Hydrotreating processes in petroleum refining were introduced more than 50 years ago for the removal of sulfur and nitrogen. The sulfided cobalt-molybdenum catalyst, together with its near relatives, is still widely used. Two oil crises made it clear that pretroleum reserves are not inexhaustible and we shall be compelled to exploid less satisfactory sources with high sulfur and nitrogen making hydrotreating even more important. This review is particularly timely for the reason that only recently has a detailed understanding of process chemistry and catalyst structure been obtained. The authors concentrate on the catalytic chemistry of the processes, dealing in some detail with the structure of the most important types of catalysts and the relationship of structure to activity.

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 original properties of mesoporous molecular sieves are so unique that the design of most existing catalysts could be reconsidered. It might indeed be of interest to introduce MMS either as a support or as the active phase, merely on the basis of their high surface areas, narrow pore size distribution and flexibility in composition. The recent literature provides examples of MMS based catalysts of many types such as acid-base solids, supported metals and supported oxides, mixed oxides, anchored complexes and clusters, grafted organic functional groups and others. Examples of all these developments are documented in the present proceedings including some spectacular new proposals. The new metallic (Pt) mesophases are specially worth mentioning because they represent a new approach to producing non-supported highly dispersed metals. In these proceedings the reader will find feature articles and regular papers from many worldwide groups, covering all aspects of synthesis, physical characterization and catalytic reactivity of MMS and their chemically modified forms. It is actually remarkable that this recent development brought together an even broader spectrum of scientists from traditionally unrelated fields such as those of liquid crystals, surfactants, sol-gels, amorphous oxides and mixed oxides, solid state, adsorbents and heterogeneous catalysts. Obviously, this is a fast-growing research area which triggers the imagination and creativity at the cross-road between material design, molecular surface tailoring and catalytic applications.