ChE Tulsa University

Dr. Geoffrey L. Price

Chairman and Professor of Chemical Engineering

Research Emphasis 

• Heterogeneous Catalysis
• Zeolites

Research

    To a large degree, this research work revolves around a central theory we proposed for the formation of active gallium centers in H-MFI (a.k.a. H-ZSM-5) which was originally developed for mechanical mixtures of Ga2O3/H-MFI :

  Ga2O3  +  2 H+Z- + 2  H2  -->   2Ga+Z- + 3H2O

The essence of this reaction is that Ga is reduced from the 3+ to 1+ oxidation state and replaces protons in the zeolite.  For mechanical mixtures, we term this process “reductive solid-state ion-exchange” (RSSIE).  Even though RSSIE was originally developed for and applied to mechanical mixtures, we have demonstrated that the essential features can be applied to all classes of Ga-containing acid-form zeolites, and hold for some other combinations of reduced metal ion/medium pore zeolites.  Such catalysts may be useful in a wide spectrum of dehydrogenation reactions other than aromatization; this was partially demonstrated in a study on amine dehydrogenations catalyzed by Ga-, Cu- and In-MFI.

    Currently, this research work focusses on adapting solid-state ion-exchange techniques to metals other than Ga, In, and Cu. Materials which are prepared via this process can be tested for applications in a wide variety of possible applications.
 

Copper Zeolites for Automotive Exhaust Treatment

    National Low Emission Vehicle (NLEV) standards and proposed Tier II emission standards for both NOx and particulates could eliminate light duty diesel engines (3-6 liter) from the US consumer market unless there is a break-through in lean catalyst technology. Lean NOx catalyst technology is about 10 years old and refers to selective catalytic reduction (SCR) of oxides of nitrogen under oxygen rich (oxidizing) exhaust conditions. The most widely studied and promising NOx catalytic system to date uses an aluminum containing zeolite (MFI) with a metal ionicly exchanged onto the acid sites within the zeolite pores. Three problems have plagued the successful implementation of this lean NOx technology: 1) sufficient catalytic activity, 2) hydrothermal stability and 3) a wide temperature range for catalytic activity. This proposal focuses on areas 1) and 2) and indirectly on 3) by attempting to identify a suitable catalytic material and the zeolitic structural factors which enhance both activity and hydrothermal stability.

    Although there is no published, comprehensive study of structural relationships between activity and hydrothermal activity, several relationships seem to appear: 1) large pore zeolite supports tend to have higher activities and lower stabilities and 2) 1-D pore systems may have higher stabilities and lower activities. In this proposed research, zeolites would be synthesized and tested based on their structural characteristics. This work is a collaboration between G. L. Price of the University of Tulsa and R. J. Blint and B. K. Cho of  General Motors funded by NSF (GOALI program) and GM. Price has the complete zeolite synthesis laboratory necessary for the small quantity synthesis of these specialized zeolites. General Motors has extensive experience in testing the reactivity and investigating the kinetics of lean NOx catalysts. Both University of Tulsa and General Motors have extensive outside interactions with the zeolite synthesis community and the automotive catalysis community.

Selected Publications

• T.F. Guidry and G.L. Price, “The Conversion of 1-Propanamine on Copper-Containing MFI and BEA Zeolites Prepared by Aqueous and Vapor Ion-Exchange”, Journal of Catalysis, 181, 16-27 (1999).
• T.F. Guidry and G.L. Price, “The Selective Dehydrogenation and Dimerization of Amines over Cu Containing MFI Zeolites” in Catalysis of Organic Reactions, F. E. Herkes, ed., Marcel Dekker, New York, pgs 601-606 (1998).
• G.L. Price, V. Kanazirev, K.M. Dooley, and V.I. Hart, “On the Mechanism of Propane Dehydrocyclization over Cation-Containing, Proton-Poor MFI Zeolite”, Journal of Catalysis, 173, 17-27 (1998).
• G.L. Price and V. Kanazirev, "Guest Ordering in Zeolite Hosts”, Zeolites 18, 33-37(1997).
• G.L. Price and V. Kanazirev, "Copper-Containing Zeolite Catalysts", U.S. Patent #5,583,081(1996).
• K.M. Dooley and G.L. Price, eds., “Gallium-loaded Zeolites and Related Systems”, Catalysis Today 31. (1996).
• K.M. Dooley, G.L. Price, V.I. Kanazirev, and V.I. Hart; “Gallium-Loaded Zeolites for Light Paraffin Aromatization: Evidence for Exchanged Gallium Cation Active Centers”, Catalysis Today 31. 305 (1996).
• M. Stojanova, Chr. Karshalykov, G.L. Price, and V. Kanazirev, "On the Reactivity of H-, Ga- and Cu-MFI Zeolites towards t-Butyl Hydroperoxide (TBHP)", Applied Catalysis A 143(1), 175 (1996).
• V. Kanazirev and G.L. Price, "The Effect of O2 on the Thermal Activation of Zeolite Beta", Journal of Catalysis 161, 156-163 (1996).
• G.L. Price, V. Kanazirev, and K.M. Dooley, "Characterization of [Ga]MFI via Thermal Analysis", Zeolites 15, 725 (1995).

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