Recent basic research in hydrodesulfurization catalysis

Hydrodesulfurization (HDS)catalysts such as Co-Mo/A₂l,O₃, and Ni-Mo/Al₂,O₃, are among the most important industrial catalysts. In spite of their widespread industrial use, very little basic nowledge has been available and the industrial developments have occurred to a large extent as a result of trial and error experiments. The introduction of new approaches and techniques to the problem has recently changed the situation. The active structures (so-called Co-Mo-S or Ni-Mo-S type structures) and active sites have been identified and characterized. This has allowed one to understand the observed catalytic behavior (e.g., the pronounced promotional effect). Insight has also been obtained regarding the parameters governing the formation of the active phase and the important role played by supports (e.g., alumina, silica, and carbon).