Oxidation is an important process in synthesizing a broad range of useful products such as polymers, pharmaceuticals, and fine chemicals. While H2O2 is a highly attractive oxidant for oxidative chemistry due to its high percentage of oxygen and environmentally friendly water byproduct, it is often used in excess due to its intrinsic instability. At large scales, the transportation of the highly concentrated H2O2 also poses high operational costs and safety concerns. Thus, the one-pot [H2O2 generation + oxidation] tandem reaction has become an important strategy to utilize this green oxidant more efficiently and economically. To implement this approach, this thesis focuses on the development of tandem catalysts that can generate H2O2 directly from H2 and O2 and consume this oxidant immediately in the subsequent oxidation. Two metal species, noble-metal nanoparticles (NPs) and MoVI complexes, were employed to catalyze each reaction step in the [H2O2 generation + alkene oxidation] tandem reaction. Specifically, a UiO-66-NH2 metal-organic framework (MOF) crystal with encapsulated NPs in its core and anchored MoVI species on its surface, has been developed for this purpose. The use of this dually functionalized core-shell catalyst in the [H2O2 generation + alkene oxidation] tandem reaction resulted in a significant enhancement of the epoxide productivity as opposed to a physical mixture of two singly functionalized catalysts. In addition, the encapsulation of the NPs inside the MOF crystal can suppress an alkene-hydrogenation side reaction, leading to a higher selectivity for the epoxide product. To demonstrate how matched reaction rates can improve the efficiency of H2O2 consumption, the alkene-oxidation step was then replaced by a faster sulfide-oxidation reaction. The bare MOF with open-coordination sites on its nodes was found to be catalytically active for sulfide oxidation, and the incorporation of VIV species on those sites further enhances the consumption of H2O2. A new reactor configuration was developed to measure the reaction rates of sulfide oxidation and H2O2 generation, enabling for both rates to be further tuned for efficient consumption of H2O2 in our tandem reaction.

Creator

• Limvorapitux, Rungmai

DOI

• https://doi.org/10.21985/n2-2011-kb85

Subject

• Chemistry

Language

• en

Alternate Identifier

• http://dissertations.umi.com/northwestern:14696
• etdadmin_upload_666644

Keyword

• Catalysis
• hydrogen peroxide generation
• oxidation
• MOFs
• tandem reaction

Date created

• 2019-01-01

Resource type

• Dissertation

Rights statement

• In Copyright