Dr. Roel Prins

Strengths and Weaknesses of EXAFS and QEXAFS Techniques Applied to Supported Metal Sulfides

Monday October 6, 2003
3:30-4:30 pm (refreshments at 3:10 pm)
Engineering Teaching and Learning Complex (ETLC) 1-007
University of Alberta

Abstract

Metal sulfides, such as MoS₂ and WS₂, promoted by Co or Ni and supported on Al₂O₃, are used in oil refineries as catalysts in hydrotreating processes to remove sulfur and nitrogen atoms from molecules in fuels. Since most oil fractions must be cleaned, hydrotreating is an important business. Environmental legislation puts higher and higher demands on the catalyst, which can only be met by the classic metal sulfide catalysts when their structure and preparation are fully understood.

Because of the importance of hydrotreating catalysts, a technique such as EXAFS, which offers the possibility of determining the structure of non-crystalline materials, has attracted considerable attention in hydrotreating. In our research we have addressed the following questions:

1. What is the structure of the sulfided Mo and W?
2. What is the structure of the Co or Ni promoter?
3. How are Mo or W and Co or Ni transformed from the oxidic precursor phase to the final sulfided phase?
4. How do additives, like fluoride, phosphate and chelating agents, improve the catalytic activity of hydrotreating catalysts?

In answering these questions, the strengths and weaknesses of EXAFS will be discussed.

About the Speaker

Roel Prins obtained his PhD in physical chemistry at the University of Amsterdam in 1967. In 1966 he joined the Shell laboratory in Amsterdam where he worked on catalysis in petroleum processing. In 1970/71 he spent a year at the Shell laboratory in Emeryville, California. In 1977 he was appointed professor of Inorganic Chemistry at the University of Technology in Eindhoven, The Netherlands. Following a sabbatical year (1986/87) in Berkeley, USA, he was appointed professor of Catalysis at the Federal Institute of Technology (ETH) in Zurich, Switzerland. Here his research concentrates on catalysis with sulfides and zeolites and EXAFS as a technique for characterizing catalysts.

He is a corresponding member of the Royal Dutch Academy of Sciences and editor of Journal of Catalysis. From 1982 to 1986 he chaired the Dutch synchrotron radiation committee, which supervised the construction of EXAFS and SAD beamlines in Daresbury, England. He was a member of the Synchrotron Radiation Committee for the Swiss-Norwegian beamline in Grenoble (France), and is presently a member of the Scientific Advisory Committee of the Swiss Synchrotron Light Source. At the ETH he served as chairman of the Laboratory for Technical Chemistry, as chairman of the Department of Chemistry, and as a member of the ETH Research Committee.