Targeted Synthesis and Characterization of Nanostructured Silicate Building Block Supports and Heterogeneous Catalysts with Tungsten(VI) or Zirconium(IV) Centers

Author

Michael Edward PeretichFollow

Date of Award

12-2011

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Chemistry

Major Professor

Craig Barnes

Committee Members

Charles Feigerle, George Schweitzer, Madhu Dhar

Abstract

Catalysts play a vital role in almost every aspect of our lives and are used in the production of fuels, polymers, chemicals, foods, and pharmaceuticals. One challenge facing the heterogeneous catalysis community is the targeted synthesis of dispersed catalyst ensembles.

The Barnes research group has developed a general methodology for the synthesis of nanostructured silicate building block supports and heterogeneous catalysts. This methodology provides researchers with the ability to control the dispersion of surface functionality, the dispersion of metal cation centers, the number of linkages from the metal cation center to the support, the surface area of the support, and the porosity of the support. This dissertation describes work aimed at synthesizing and characterizing nanostructured silicate building block supports and heterogeneous catalysts.

Nanostructured silicate building block supports were synthesized by reacting SiCl₄py₂ with Si₈O₁₂(OSnMe₃)₈. The resulting supports contained spatially isolated Me₃Sn groups and the density of Me₃Sn groups was targeted by varying the stoichiometric ratio of reactants. The stoichiometric ratio of reactants also controlled the surface area and porosity of the supports.

Nanostructured heterogeneous catalysts with isolated tungsten(VI) or zirconium(IV) centers were synthesized by reacting a limiting amount of a metal chloride with either Si₈O₁₂(OSnMe₃)₈ or a premade silicate building block support. Two types of catalysts ensembles were targeted: embedded and surface. Embedded ensembles were successfully targeted using WOCl₄ and ZrCl₄ while the reaction between WCl₆ and the building block did not result in the preparation of the targeted ensemble. However the resulting ensemble was thoroughly characterized even though the targeted ensemble was not produced. In all three cases a single type of catalyst ensembles was synthesized and a high surface area silicate support was generated around the embedded ensembles without disrupting the ensemble itself. Surface ensembles were successfully targeted using ZrCl₄. The reaction between the tungsten chlorides (WOCl₄ and WCl₆) and the premade support did not result in the preparation of the targeted ensembles however the resulting ensembles were thoroughly characterized.

Recommended Citation

Peretich, Michael Edward, "Targeted Synthesis and Characterization of Nanostructured Silicate Building Block Supports and Heterogeneous Catalysts with Tungsten(VI) or Zirconium(IV) Centers. " PhD diss., University of Tennessee, 2011.
https://trace.tennessee.edu/utk_graddiss/1215