Keywords

heterogeneous catalysis, hydrogenation, nickel foam, atomic layer deposition, platinum catalyst, palladium catalyst

Abstract

Noble metal catalysts are widely used for their remarkable activity and stability. However, their sustainability is challenged by their scarcity, both in terms of Earth-abundance and production sources. To ensure their sustainable use and long-term availability, it is essential to design new catalytic systems that minimize noble metal usage, maximize reactivity, and allow easy recovery and reuse. One promising approach involves using supported noble metal nanocatalysts (NCs) that enables low loadings of active materials, prevents NCs agglomeration during catalysis, and enhances separability of the catalysts from products. Nickel foams, as NCs support, stand out for their contiguous macroporous 3-D structure that guarantees full coverage of NCs, easy handling, stability, recyclability, cost-effectiveness, and availability. In this dissertation, we present facile approaches to prepare highly reactive, robust, and reusable noble-metal-based NCs encapsulated with an approximately 2 nm overcoat of Al2O3 onto Ni foams. Catalyst design and synthesis, reactivity scope, and selectivity sources in the reaction systems are the main focus of this research. In the first project, Al2O3-coated Pt NCs on Ni foams were prepared and tested for the hydrogenation of various functionalized styrenes at mild reaction conditions in benign solvents. The material showed excellent catalytic activity (TOF > 9 × 106 h−1) and reusability over 10 recycling styrene hydrogenation trials (240 hours of utilization), high tolerance towards F, Cl, and Br substituents, and no hydrogenation of the aromatic ring. Characterizations revealed ALD Al2O3 enhanced the stability of Pt NCs and NiOx nanoplates on the foam surface. In the second project, Al2O3-coated Pd NCs on dopamine treated Ni foams were prepared. The material demonstrated outstanding performance in hydrogenation of functionalized nitrobenzenes and styrenes at low temperatures and H2 pressure. The monolith material with evenly-coated Pd NCs (approximately 16 nm in diameter) proved to be highly robust and reusable. Finally, the membrane-like Pd-based catalyst was exploited to continuous flow hydrogenation of both styrene and nitrobenzene in a packed bed reactor.

Completion Date

2024

Semester

Spring

Committee Chair

Jurca, Titel

Degree

Doctor of Philosophy (Ph.D.)

College

College of Sciences

Department

Chemistry

Degree Program

Chemistry

Format

application/pdf

Language

English

Rights

In copyright

Release Date

November 2024

Length of Campus-only Access

None

Access Status

Doctoral Dissertation (Open Access)

Campus Location

Orlando (Main) Campus

Accessibility Status

Meets minimum standards for ETDs/HUTs

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