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Synthesis, Characterization, and Catalytic Performance of Metal-Organic Frameworks (MOFs) and MOF-Templated Materials

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posted on 2015-11-03, 00:00 authored by Nicholas Dennis McNamara

New technology is needed for desulfurization of petroleum streams due to the increasing sulfur content of petroleum input to refineries in the U.S. coupled with the increasingly stringent regulations on sulfur content levied by the EPA. Hydrodesulfurization is the current method of desulfurization in industry, but this method struggles to remove refractory thiophenic compounds. Oxidative desulfurization (ODS) offers the promise of easier removal of these compounds as a complementary process. However, the petroleum industry has yet to adopt this technology as common practice. A major challenge in implementing the ODS process commercially is the need for highly active, selective, and stable catalysts. Metal-organic frameworks (MOFs) and MOF-templated materials have shown promise as heterogeneous catalysts for a number of different chemical transformations including the oxidation of sulfur compounds, however, this research area is relatively new and therefore, underdeveloped.

To that end, this dissertation documents the synthesis, characterization, and utilization of MOFs and MOF-templated materials specifically designed and synthesized to perform as active and stable catalysts for the oxidation of thiophenic compounds. Initially, two existing MOFs, (V) MIL-47 and (Ti) MIL-125, were evaluated for catalytic activity and stability in the oxidation of thiophenic compounds. It was determined that while (V) MIL-47 was more active, it was less stable than (Ti) MIL-125. MIL-125 had a lower activity due, in part, to its small pore size, which limited access to active sites. Therefore, a method to incorporate mesoporosity in the typically microporous MIL-125 structure was developed. This hierarchically porous MIL-125 material was found to be a more active catalyst than its microporous analogue due to increased accessibility of reactant molecules to active sites. MOFs, while active for a number of chemical transformations, tend to have limited thermal and chemical stability. Therefore, multiple methods of thermal transformation of MOFs were employed to synthesize materials composed of Ti nanoparticles supported on porous carbons. These newly synthesized materials exhibited high activities and stabilities in the oxidation of dibenzothiophene. Furthermore, the final materials’ properties could be tuned by altering the precursor materials and pyrolysis conditions.

History

Date Created

2015-11-03

Date Modified

2022-10-06

Defense Date

2015-08-05

Research Director(s)

Jason C. Hicks

Committee Members

Joan Brennecke William Phillip William Schneider

Degree

  • Doctor of Philosophy

Degree Level

  • Doctoral Dissertation

Language

  • English

Alternate Identifier

962921605

Library Record

4491831

OCLC Number

962921605

Additional Groups

  • Chemical and Biomolecular Engineering

Program Name

  • Chemical and Biomolecular Engineering

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