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Design, Development, Characterization, and Catalytic Activity Exploration of Single-Site Carbon-Supported Molybdenum Dioxo Catalysts.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Design, Development, Characterization, and Catalytic Activity Exploration of Single-Site Carbon-Supported Molybdenum Dioxo Catalysts.
Author:	Liu, Yiqi.
Published:	Ann Arbor : ProQuest Dissertations & Theses, 2023
Description:	132 p.
Notes:	Source: Dissertations Abstracts International, Volume: 85-06, Section: B.
Notes:	Advisor: Marks, Tobin.
Contained By:	Dissertations Abstracts International85-06B.
Subject:	Chemistry.
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=30689964
ISBN:	9798381174656

Design, Development, Characterization, and Catalytic Activity Exploration of Single-Site Carbon-Supported Molybdenum Dioxo Catalysts.
Liu, Yiqi.

Design, Development, Characterization, and Catalytic Activity Exploration of Single-Site Carbon-Supported Molybdenum Dioxo Catalysts. - Ann Arbor : ProQuest Dissertations & Theses, 2023 - 132 p.

Source: Dissertations Abstracts International, Volume: 85-06, Section: B.

Thesis (Ph.D.)--Northwestern University, 2023.

This item must not be sold to any third party vendors.

Single-site heterogeneous catalysts (SSHC) are at the interface between homogeneous and heterogeneous catalysis, providing well-defined catalytically active sites with enhanced atom efficiency, catalytic selectivity, and simplified mechanistic studies. Here, single-site MoO2 catalysts are grafted onto various carbon supports, such as activated carbon (AC), carbon nanohorns (CNH), and reduced graphene oxide (rGO). The molecular architectures and electronic structures of these catalysts have been definitively characterized by state-of-the-art techniques. Mo 3d5/2 XPS assigns the oxidation state as Mo(VI), while NH3-TPD reveals that anchored MoO2 sites do not have strong acidity. DRIFTS assigns features at 959 cm-1 and 927 cm-1 to the symmetric and anti-symmetric Mo=O stretching modes of a cis-(O=Mo=O) moiety, in good agreement with DFT computation. Moreover, EXAFS fittings are consistent with isolated (C-O)2-Mo(=O)2 species with two Mo=O bonds and two Mo-O bonds. SMART-EM images suggest that single Mo atoms bind to the graphitic surface in an out-of-plane binding mode. Efficient hydroboration of aldehydes and ketones mediated by AC/MoO2 has also been studied. The reaction exhibits chemoselectivity towards carbonyl reduction over alkene, alkyne, nitrile, and ester functionalities. An in-depth understanding of the catalytic cycle and catalyst deactivation pathway is achieved with a combined experimental and computational analysis. The presence of excess benzaldehyde can mitigate HBpin poisoning effect, providing higher catalyst recyclability. Overall, this dissertation showcases a well-defined and versatile single-site carbon-supported MoO2 heterogeneous catalytic system.

ISBN: 9798381174656Subjects--Topical Terms:

188628
Chemistry.
Subjects--Index Terms:

Single-site heterogeneous catalysts

Design, Development, Characterization, and Catalytic Activity Exploration of Single-Site Carbon-Supported Molybdenum Dioxo Catalysts.
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245 1 0 $a Design, Development, Characterization, and Catalytic Activity Exploration of Single-Site Carbon-Supported Molybdenum Dioxo Catalysts.
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502 $a Thesis (Ph.D.)--Northwestern University, 2023.
506 $a This item must not be sold to any third party vendors.
520 $a Single-site heterogeneous catalysts (SSHC) are at the interface between homogeneous and heterogeneous catalysis, providing well-defined catalytically active sites with enhanced atom efficiency, catalytic selectivity, and simplified mechanistic studies. Here, single-site MoO2 catalysts are grafted onto various carbon supports, such as activated carbon (AC), carbon nanohorns (CNH), and reduced graphene oxide (rGO). The molecular architectures and electronic structures of these catalysts have been definitively characterized by state-of-the-art techniques. Mo 3d5/2 XPS assigns the oxidation state as Mo(VI), while NH3-TPD reveals that anchored MoO2 sites do not have strong acidity. DRIFTS assigns features at 959 cm-1 and 927 cm-1 to the symmetric and anti-symmetric Mo=O stretching modes of a cis-(O=Mo=O) moiety, in good agreement with DFT computation. Moreover, EXAFS fittings are consistent with isolated (C-O)2-Mo(=O)2 species with two Mo=O bonds and two Mo-O bonds. SMART-EM images suggest that single Mo atoms bind to the graphitic surface in an out-of-plane binding mode. Efficient hydroboration of aldehydes and ketones mediated by AC/MoO2 has also been studied. The reaction exhibits chemoselectivity towards carbonyl reduction over alkene, alkyne, nitrile, and ester functionalities. An in-depth understanding of the catalytic cycle and catalyst deactivation pathway is achieved with a combined experimental and computational analysis. The presence of excess benzaldehyde can mitigate HBpin poisoning effect, providing higher catalyst recyclability. Overall, this dissertation showcases a well-defined and versatile single-site carbon-supported MoO2 heterogeneous catalytic system.
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