Synthesis and Characterization of V-MCM-41 and V-SBA-15 Catalysts for C-1 Hydrocarbon Oxidation

2009 Spring Symposium

 
Gary Haller
Department of Chemistry
Yale University
New Haven, CT


Abstract – Mobil composition of material No. 41 (MCM-41) was disclosed in 1992 and shortly after a research project was initiated at Yale to use these materials to demonstrate a radius of curvature effect on catalytic activity. The “radius of curvature” effect implies a change in the solid surface tension of the pore wall as the pore diameter (curvature) is changed that is expected to change the activity/selectivity of an isolated catalytic site on the pore wall of the support. An isolated site can be formed by isomorphous substitution (during synthesis) of some Si cations by V cations in the MCM-41 silica matrix. Several labs have reported that isolated V sites on a silica support are preferable to dimers, oligomers or polymers of vandia on a silica support for the oxidation of methanol to formaldehyde. MCM-41 might have an advantage relative to other silicas because of its very high surface area, >1000 m2/g. Both the air oxidation of methanol and methane to formaldehyde have been used as probe reactions for catalytic characterization of V-MCM-41. SBA-15 has a similar structure to MCM-41, but larger pores and thicker walls. Isomorphous substitution of V during synthesis is not practical, but well dispersed V can be prepared post-synthesis by grafting (reaction with surface hydroxyls). The activity for methanol oxidation on V-MCM-41 and V-SBA-15 will be compared and discussed.

Speaker’s Biography – Gary L. Haller is the Henry Prentiss Becton Professor of Engineering and Applied Science at Yale University with joint appointments in the Departments of Chemical Engineering and Chemistry. Professor Haller received a B.S. in mathematics and chemistry from the University of Nebraska at Kearney in 1962 and a Ph.D. in physical chemistry from Northwestern University in 1966. Following a NATO Post-doctoral Fellowship at Oxford University, he joined the faculty of Yale where he has held a variety of administrative posts that include Chair of the Department of Chemical Engineering, Chair of the Council of Engineering, and Deputy Provost for Physical Sciences and Engineering. He was Master of Jonathan Edwards College, one of twelve residential colleges that comprise Yale College 1997-2008.

Professor Haller’s research involved the molecular understanding of heterogeneous catalysts. His research combines the inorganic chemistry of catalyst synthesis, physical chemistry of spectroscopic characterization of heterogeneous catalysts, and the kinetics and mechanism of simple organic reactions. Current research is focused on catalysts for the synthesis of single walled carbon nanotubes and the application of these carbon nanotubes as supports for novel catalytic reactions such as aqueous phase reforming (a route to renewable energy sources).