Date of Award

Fall 2023

Document Type

Open Access Dissertation

Department

Chemical Engineering

First Advisor

John R. Regalbuto

Second Advisor

John Monnier

Abstract

Typical heterogeneous catalysts consist of transition metal nanoparticles anchored against sintering on an inert, porous, high temperature stable support. The synthesis of supported catalyst involves pretreatment (drying, reduction) of deposited, ionic metal precursor complexes to form metal nanoparticles. In the first part of this work, we aim to understand the influence of pretreatment (reduction temperature, heating rate, moisture content) on final particle size. Supported nanoparticles of Pt and Pd were synthesized by strong electrostatic adsorption (SEA) and dry impregnation (DI). Reduced samples were characterized by in-situ and ex-situ XRD and STEM. The DI-derived samples generally showed an expected increase of particle size with increased reduction temperature, and severe particle coalescence in humid hydrogen, while the SEA-derived samples did not sinter at the elevated reduction temperatures (up to 500°C) and were remarkably stable in the humid reducing environment.

In the second part of the study, simultaneous strong electrostatic adsorption is pushed to the limit of metal dilution to prepare single-atom sites on a supported nanoparticle of another relatively inert metal. Supported nickel prepared by SEA shows very low activity in aqueous-phase furfural hydrogenation reaction (T=150°C, P=430 psig). Adding a small amount of palladium to form Pd1Ni dilute limit alloy (DLA) shows about two orders of magnitude increase in activity at 10% furfural conversion. This study investigates the effect of reaction conditions such as temperature and hydrogen pressure on aqueous phase furfural hydrogenation using palladium-nickel DLA on a 100 mL autoclave reactor in batch operation.

Heavy oils are difficult and costly to transport and refine. Therefore, reducing the viscosity of heavy oil at the wellhead to make it easily and cheaply transferable via pipeline has always been an important task. Heavy crude oil has poor response to microwave energy and cannot be heated directly to the required high temperatures to carry out cleavage reaction and reduce its viscosity. In this part of the study, we developed low-cost microwave absorbing nano-catalysts using the SEA method. When tested for crude oil upgradation by microwave heating, addition of less than 1wt% of the catalyst induced more than 90% viscosity reduction at temperature below 100°C.

Rights

© 2024, Md Fakhruddin Patwary

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