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 development of a commercially successful process for the catalytic synthesis of ammonia was a scientific as well as a technical triumph. Its implications were conƯ siderable. It demonstrated the power of a combination of innovative technology and engineering together with basic chemical science, and it introduced ideas and techniques into catalytic science and process engineering which are still with us today. In a real sense, this process changed the face of industrial chemistry and process technology. Of course, the key step in the direct synthesis of ammonia was the development of an efficient catalyst, and the historical account given by Dr. S.A. Topham in the first chapter of this volume shows how this was successƯ fully accomplished, and how this was combined with the successful solution of other daunting technical problems to make the overall process possible. The microstructure of a catalyst is an important feature which determines its behaviour, and the electron microscope is one of the most important instrumental methods by means of which structural and microstrucƯ tural information can be obtained. Nevertheless, the elecƯ tron-optical processes of image formation are complex, but need to be properly understood if image interpretaƯ tion is to be done reliably. In the second chapter of this volume, Dr. J.V. Sanders addresses the entire field of the application of electron microscopic methods to the examination of catalysts Front Matter....Pages I-XV Hydrotreating Catalysis....Pages 1-269 Back Matter....Pages 271-312
