Luận văn thạc sĩ nghiên cứu quá trình oxy hóa hiếu khí của rượu trên cấu trúc nano kim loại Được hỗ trợ bằng oxit vai trò của hạt nano so với các nguyên tử Đơn lẻ cô lập

Conversion and selectivity of benzaldehyde over RWTiO2-4 Figure 4, 10, Selectivity of benzaldehyde and tumn-over frequency TOK of RTA and leaching Ru/TiOz-4 catalysts.. Effect of reactio

DAI HOC BACH KHOA HA NOI

LUAN VAN THAC Si

Nghiên cứu quá trình oxy hoá hiếu khí của rượu

trên cầu trúc nano kim loại được hỗ trợ bằng oxit

— Vai trò của hạt nano so với các nguyễn tử đơn lẻ

CONG HOA XA HOT CHU NGHIA VIRT NAM

Độc lập — Ty do— Hanh phic

BAN XAC NHAN CHINH SUA LUAN VAN THAC SI

Hg va tén tac gid lua ăn: Mạc Văn Hưng

Tử tài luận văn: Nghiên cứu quá trinh oxy hoá hiểu khí của rượu trên câu

trúc nano kim loại được hề trợ bằng oxit — Vai trò của hạt nano so với cáo nguyễn

tử đơn lẻ cô lập

Chuyên ngành: Hoá học

Mã số học viên: 20211200ML

Tác giả, Người hướng dẫn khoa học và Hội đẳng cham hain văn xác nhận

ta chữa, bỗ sung luận văn theo biên bản hop Hội đồng ngày 26/10/2023

với oác nội dung sau:

~_ Chính sửa lỗi chỉnh tả, trình bảy,

~ Đã bổ sung một sỏ chỉ tiết thực nghiệm

~_ Đã bổ sung, chỉnh sửa một số giải thích

Ngày tháng năm

Giảng viên hướng dẫn Tác giá luận văn

CHỦ TỊCH HỘI ĐỒNG

HANOI UNIVERSITY OF SCLENCE AND TECHOLOGY

MASTER THESIS

Aerobic oxidation of alcohols on the oxide-

supported metal nanostructures - role of

nanoparticle versus to the single atoms

MAC VAN HUNG

Hung MV211200M@sis.hust.edu.vn

Master of Scicence in Chemistry

Supervisor: Assoc Prof Dr Vu Anh Tuan

Signature

Institute: Chemical Engineering Institute

Tanoi, 10/2023

LIST OF FIGURES

Figure 2 1 Crystal bulk structure of (a) anatase, (b) rutile, and (c) brookite

11

Figure 2 2 ‘the SMSI effect occwzing during the reduction treatment by

‘Hh The gray circles represent metallic nanoparticles, while the blue parts represent

Vigure 2 3 Biomimetic aerobie oxidation of aloohols 7

Figure 2 4 Schematic illustrate the changes of surface itve energy and specific activily per mela! alom with metal particle size and the support el

13 OM

Figure 2 5, Methods for preparmg ISAS catalyst: mass-selected soft-

landing (A) and wet chemistry (B) ào cac — ˆ

Figure 2 6 Two-dimensional representation for the derivation of the Bragg

Figure 2 7 Clasaificntin o[physisorption isotherms 23 Figure 2 8 Schematic of image formation in a STEM, showing the on-axis small brighi-field detector and the larger annular dark-field detector, pink 26

Figure 2 9, Dehydrogenation mechanism of alcchol oxidation over Pt

Figure 2 10 Evolution of geometric and electronic structures of single

atom, metal clusters, and nanoparticles -csss2tsseerseersersee.e.- 28

Figure 2 11, Reaction scheme for the benzyl alechol oxidalion 29 Figue 3 1 Schematic illustration of the preparation of RwTiO2z

igure 4 2 (@) No adsorption-desorption isotherms and (b) pore size

distribution curves 3 of different loading, Ru/li0: catalysts —-

Tipure 4 3 HAAD-STEM/RDX elememal mapping of (ai-a4) Ru/TiOs-l,

Cy -ba) RuTiOa-2, (cr-ca) Rev TiO23, and (died) Ru/TIO2-4 36

Figure 4 4 HAAD-STEM images of (a-b) RwTi0:-1, (c-d) RWTi02-2, (c- f) Ru/liOe-3, and (g-h) Ru/TiO2-4, and (i) the Ru particle size distribution of

Figure 4 5 XPS spectra of Ru 3d/C Is region of the Ru catalysts 38 Figure 4 6 XPS spectra of O Is and Ti 2p of the RWTiO2 catalysts 39

Figure 4 7 H2-TPR profiles of the four Ru/TiO2 catalysis 40

Figure 4 8 Conversion and selectivity of benzaldehyde over RWTiO2-4

Figure 4, 10, Selectivity of benzaldehyde and tumn-over frequency (TOK) of

RTA and leaching Ru/TiOz-4 catalysts - - 43

Figure 4 11, XRD spectrum of Ru/TiOz-4 anđ Ru/TiO-4 leaching catalyst

aM Figure 4 12 Effect of reaction temporature on the conversion and seleptivily [or aerobic oxidation of benzyl alechol 44

Figure 4 13 Effect of solvent on conversion and selectivity for aerobic oxidation of benzy] alcolioL -: sàn 211102 1e AS

Figure 4 14 XRD spectrum of four spent Ru/TiQ) catalysis 46

LIST OF FIGURES

Figure 2 1 Crystal bulk structure of (a) anatase, (b) rutile, and (c) brookite

11

Figure 2 2 ‘the SMSI effect occwzing during the reduction treatment by

‘Hh The gray circles represent metallic nanoparticles, while the blue parts represent

Vigure 2 3 Biomimetic aerobie oxidation of aloohols 7

Figure 2 4 Schematic illustrate the changes of surface itve energy and specific activily per mela! alom with metal particle size and the support el

13 OM

Figure 2 5, Methods for preparmg ISAS catalyst: mass-selected soft-

landing (A) and wet chemistry (B) ào cac — ˆ

Figure 2 6 Two-dimensional representation for the derivation of the Bragg

Figure 2 7 Clasaificntin o[physisorption isotherms 23 Figure 2 8 Schematic of image formation in a STEM, showing the on-axis small brighi-field detector and the larger annular dark-field detector, pink 26

Figure 2 9, Dehydrogenation mechanism of alcchol oxidation over Pt

Figure 2 10 Evolution of geometric and electronic structures of single

atom, metal clusters, and nanoparticles -csss2tsseerseersersee.e.- 28

Figure 2 11, Reaction scheme for the benzyl alechol oxidalion 29 Figue 3 1 Schematic illustration of the preparation of RwTiO2z

igure 4 2 (@) No adsorption-desorption isotherms and (b) pore size

distribution curves 3 of different loading, Ru/li0: catalysts —-

Tipure 4 3 HAAD-STEM/RDX elememal mapping of (ai-a4) Ru/TiOs-l,

Cy -ba) RuTiOa-2, (cr-ca) Rev TiO23, and (died) Ru/TIO2-4 36

Figure 4 4 HAAD-STEM images of (a-b) RwTi0:-1, (c-d) RWTi02-2, (c- f) Ru/liOe-3, and (g-h) Ru/TiO2-4, and (i) the Ru particle size distribution of

Figure 4 5 XPS spectra of Ru 3d/C Is region of the Ru catalysts 38 Figure 4 6 XPS spectra of O Is and Ti 2p of the RWTiO2 catalysts 39

LIST OF FIGURES

Figure 2 1 Crystal bulk structure of (a) anatase, (b) rutile, and (c) brookite

11

Figure 2 2 ‘the SMSI effect occwzing during the reduction treatment by

‘Hh The gray circles represent metallic nanoparticles, while the blue parts represent

Vigure 2 3 Biomimetic aerobie oxidation of aloohols 7

Figure 2 4 Schematic illustrate the changes of surface itve energy and specific activily per mela! alom with metal particle size and the support el

13 OM

Figure 2 5, Methods for preparmg ISAS catalyst: mass-selected soft-

landing (A) and wet chemistry (B) ào cac — ˆ

Figure 2 6 Two-dimensional representation for the derivation of the Bragg

Figure 2 7 Clasaificntin o[physisorption isotherms 23 Figure 2 8 Schematic of image formation in a STEM, showing the on-axis small brighi-field detector and the larger annular dark-field detector, pink 26

Figure 2 9, Dehydrogenation mechanism of alcchol oxidation over Pt

Figure 2 10 Evolution of geometric and electronic structures of single

atom, metal clusters, and nanoparticles -csss2tsseerseersersee.e.- 28

Figure 2 11, Reaction scheme for the benzyl alechol oxidalion 29 Figue 3 1 Schematic illustration of the preparation of RwTiO2z

igure 4 2 (@) No adsorption-desorption isotherms and (b) pore size

distribution curves 3 of different loading, Ru/li0: catalysts —-

Tipure 4 3 HAAD-STEM/RDX elememal mapping of (ai-a4) Ru/TiOs-l,

Cy -ba) RuTiOa-2, (cr-ca) Rev TiO23, and (died) Ru/TIO2-4 36

Figure 4 4 HAAD-STEM images of (a-b) RwTi0:-1, (c-d) RWTi02-2, (c- f) Ru/liOe-3, and (g-h) Ru/TiO2-4, and (i) the Ru particle size distribution of

Figure 4 5 XPS spectra of Ru 3d/C Is region of the Ru catalysts 38 Figure 4 6 XPS spectra of O Is and Ti 2p of the RWTiO2 catalysts 39

LIST OF TABLES Table 1 Properties of anatase, rutile, and brookite 12

‘fable 2 Ru loading and textural properties of the prepared catalysts 36

Table 3 The TiO, crystallite and H, uptake and FHWM value of four

Tablc 4 Conveision and selectivity of fowr Ru/TIO¿ catalysts 42

Table $ Conversion and selectivity of RWTiO2-4 catalyst with different

temperatures and solvents - - 45

ACKNOWLEDGMENTS

First of all, I would like to like to give my gratitude to my co-supervisors

Dr Ali Mohamed Abdel-Mageed (Surface Chemistry in Applied Catalysis, LIKAT) and Assoc Prof Dr Vu Anh Tuan (Department of Analytical Chemis HUST), for their help and support throughout imy thesis work ‘there are no words that can express my appreciation for everything that they have done for me

Tam also extremely grateful lo my colleagues in the group, Dr Jawaher Mosrati, Dr Katja Neubauer, M.Sc Evaristo Salaya, M.Sc Sebastian Lobner, Dr Mohammed Al-yusufi, Mrs Julia Schroeder They have tanght me many things in

a year

I would like to thank to Mrs Anja Simmula for ICP measurements, Mr Reinhard Rekell for nibegen adsorplion, and Dr Hanan Ata for Hz-TPR micasuroments Thank should also go to Service Depariment Analyties for XRD, and XPS analysis

1 would like to thank the RoHan project for giving me the excellent opportunity to study in Germany with full financial support

Lastly, it is impossible not to mention my family and friends, especially my parents, my brother, who gave me encouragement and emotional support along the research path

ABTRACT

‘the oxidation of alcohols to the corresponding carbonyl compounds, such

as aldehydes, ketones, and carboxylic acids, has received the most attention These

compounds are versatile and valuable intermediates in manufacturing pharmaccuticals, perfumes, and flavorings [1] The catalytic performance of metal nanoparticles in the oxidation of alcohol reactions can be influcnced by many factors, including the size and shape of melal clusters and nanoparticles,

promoters, and interactions between supports and active sites Ru has attracted considerable interest in catalysis not only because of its relatively low cost

compared to commonly studied and industrially applied noble metals such as Au,

Tt, Pd, but also due to its tunability by different support effects, especially in

combination with T1O: Here, we aim to at identification of the role of Ru

janoparticle versus to the single atoms for catalytic activity and product selectrvity

in the aerobic oxidation of benzyl alechol

Ru/TiOy catalysis were prepared using a wetness impregnation method The

Ru particle size was controled by varing the Ru loading from 0.2 to 3.0 wi% The materials were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (MPS), high-angle annular dark field scanning transmission electron

amieroscopy (HAADF-STHM) and energy dispersive spectroscopy (EDS), Hạ-

temperature-programmed-reduction (IPR) The state oxidation of Ru on ‘TiO: support is metallic Ru and Ru* for the fresh catalyst and Ru‘* for the spent catalysl The HAAD-STEM resulls show the highly disparsed Ru on the supporl,

1

ACKNOWLEDGMENTS

First of all, I would like to like to give my gratitude to my co-supervisors

Dr Ali Mohamed Abdel-Mageed (Surface Chemistry in Applied Catalysis, LIKAT) and Assoc Prof Dr Vu Anh Tuan (Department of Analytical Chemis HUST), for their help and support throughout imy thesis work ‘there are no words that can express my appreciation for everything that they have done for me

Tam also extremely grateful lo my colleagues in the group, Dr Jawaher Mosrati, Dr Katja Neubauer, M.Sc Evaristo Salaya, M.Sc Sebastian Lobner, Dr Mohammed Al-yusufi, Mrs Julia Schroeder They have tanght me many things in

a year

I would like to thank to Mrs Anja Simmula for ICP measurements, Mr Reinhard Rekell for nibegen adsorplion, and Dr Hanan Ata for Hz-TPR micasuroments Thank should also go to Service Depariment Analyties for XRD, and XPS analysis

1 would like to thank the RoHan project for giving me the excellent opportunity to study in Germany with full financial support

Lastly, it is impossible not to mention my family and friends, especially my parents, my brother, who gave me encouragement and emotional support along the research path

ABTRACT

‘the oxidation of alcohols to the corresponding carbonyl compounds, such

as aldehydes, ketones, and carboxylic acids, has received the most attention These

compounds are versatile and valuable intermediates in manufacturing pharmaccuticals, perfumes, and flavorings [1] The catalytic performance of metal nanoparticles in the oxidation of alcohol reactions can be influcnced by many factors, including the size and shape of melal clusters and nanoparticles,

promoters, and interactions between supports and active sites Ru has attracted considerable interest in catalysis not only because of its relatively low cost

compared to commonly studied and industrially applied noble metals such as Au,

Tt, Pd, but also due to its tunability by different support effects, especially in

combination with T1O: Here, we aim to at identification of the role of Ru

janoparticle versus to the single atoms for catalytic activity and product selectrvity

in the aerobic oxidation of benzyl alechol

Ru/TiOy catalysis were prepared using a wetness impregnation method The

Ru particle size was controled by varing the Ru loading from 0.2 to 3.0 wi% The materials were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (MPS), high-angle annular dark field scanning transmission electron

amieroscopy (HAADF-STHM) and energy dispersive spectroscopy (EDS), Hạ-

temperature-programmed-reduction (IPR) The state oxidation of Ru on ‘TiO: support is metallic Ru and Ru* for the fresh catalyst and Ru‘* for the spent catalysl The HAAD-STEM resulls show the highly disparsed Ru on the supporl,

1

Figure 4 7 H2-TPR profiles of the four Ru/TiO2 catalysis 40

Figure 4 8 Conversion and selectivity of benzaldehyde over RWTiO2-4

Figure 4, 10, Selectivity of benzaldehyde and tumn-over frequency (TOK) of

RTA and leaching Ru/TiOz-4 catalysts - - 43

Figure 4 11, XRD spectrum of Ru/TiOz-4 anđ Ru/TiO-4 leaching catalyst

aM Figure 4 12 Effect of reaction temporature on the conversion and seleptivily [or aerobic oxidation of benzyl alechol 44

Figure 4 13 Effect of solvent on conversion and selectivity for aerobic oxidation of benzy] alcolioL -: sàn 211102 1e AS

Figure 4 14 XRD spectrum of four spent Ru/TiQ) catalysis 46

COTENTS

COTENTS

LIST OF FIGURES

LIST OF TABLES LIST OF ABBREVIATIONS CHAPTER 1 INTRODUCTIO® 1.1 Background - - 9

1.2 The objectives of the thesis ca TÔ CHAPTER 2 THEORTCAT BASTS

2.1 Titantim đioxide wll 2.1.1 Proper and siructure of titanium dioxide - 11

2.1.2, TiOa as catalyst guppOIf, co " 2 2.1.3 Synthesis of TiO, - 14 2.2 Ruflienruim cà ciinereteerrirerirerrirree ¬ )

3.2.1 Physicochemical properties and application of ruthenium 15

2.2.2 Ru-based catalysts for oxidation of alcohol LÕ 2.3 Isolated single-alom-site calalysLs 18 2.3.1 Concept and properties of isolated single-atom-site catalysts 18 2.3.2, Preparation of isolated single-alom-sile calalysls 19

2.4, Analytical methods .cccscssctsoisnnvtnsenessenseee ¬

3.4.1 X-ray điữaction (XRD) - - 21

2.3.2 Niưogen adsorption at 77 K

23.2 Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES) 24 3.3.3 X-ray photoelectron spegtrOsGOpy suasa.24 2.3.4, High-angle annular dark field scanning transmission electron microscopy (HAADF-STEM) and energy dispersive spectroscopy (EDS) 25 2.5 Aerobic oxidation of aleohol CHAPTER 3 EXPERIMENT SECTION

3.1 Preparation of catalyst

3.2 Catalyst characterization - 30

LIST OF TABLES Table 1 Properties of anatase, rutile, and brookite 12

‘fable 2 Ru loading and textural properties of the prepared catalysts 36

Table 3 The TiO, crystallite and H, uptake and FHWM value of four

Tablc 4 Conveision and selectivity of fowr Ru/TIO¿ catalysts 42

Table $ Conversion and selectivity of RWTiO2-4 catalyst with different

temperatures and solvents - - 45

LIST OF TABLES Table 1 Properties of anatase, rutile, and brookite 12

‘fable 2 Ru loading and textural properties of the prepared catalysts 36

Table 3 The TiO, crystallite and H, uptake and FHWM value of four

Tablc 4 Conveision and selectivity of fowr Ru/TIO¿ catalysts 42

Table $ Conversion and selectivity of RWTiO2-4 catalyst with different

temperatures and solvents - - 45

LIST OF TABLES Table 1 Properties of anatase, rutile, and brookite 12

‘fable 2 Ru loading and textural properties of the prepared catalysts 36

Table 3 The TiO, crystallite and H, uptake and FHWM value of four

Tablc 4 Conveision and selectivity of fowr Ru/TIO¿ catalysts 42

Table $ Conversion and selectivity of RWTiO2-4 catalyst with different

temperatures and solvents - - 45

COTENTS

COTENTS

LIST OF FIGURES

LIST OF TABLES LIST OF ABBREVIATIONS CHAPTER 1 INTRODUCTIO® 1.1 Background - - 9

1.2 The objectives of the thesis ca TÔ CHAPTER 2 THEORTCAT BASTS

2.1 Titantim đioxide wll 2.1.1 Proper and siructure of titanium dioxide - 11

2.1.2, TiOa as catalyst guppOIf, co " 2 2.1.3 Synthesis of TiO, - 14 2.2 Ruflienruim cà ciinereteerrirerirerrirree ¬ )

3.2.1 Physicochemical properties and application of ruthenium 15

2.2.2 Ru-based catalysts for oxidation of alcohol LÕ 2.3 Isolated single-alom-site calalysLs 18 2.3.1 Concept and properties of isolated single-atom-site catalysts 18 2.3.2, Preparation of isolated single-alom-sile calalysls 19

2.4, Analytical methods .cccscssctsoisnnvtnsenessenseee ¬

3.4.1 X-ray điữaction (XRD) - - 21

2.3.2 Niưogen adsorption at 77 K

23.2 Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES) 24 3.3.3 X-ray photoelectron spegtrOsGOpy suasa.24 2.3.4, High-angle annular dark field scanning transmission electron microscopy (HAADF-STEM) and energy dispersive spectroscopy (EDS) 25 2.5 Aerobic oxidation of aleohol CHAPTER 3 EXPERIMENT SECTION

3.1 Preparation of catalyst

3.2 Catalyst characterization - 30

LIST OF TABLES Table 1 Properties of anatase, rutile, and brookite 12

‘fable 2 Ru loading and textural properties of the prepared catalysts 36

Table 3 The TiO, crystallite and H, uptake and FHWM value of four

Tablc 4 Conveision and selectivity of fowr Ru/TIO¿ catalysts 42

Table $ Conversion and selectivity of RWTiO2-4 catalyst with different

temperatures and solvents - - 45

COTENTS

COTENTS

LIST OF FIGURES

LIST OF TABLES LIST OF ABBREVIATIONS CHAPTER 1 INTRODUCTIO® 1.1 Background - - 9

1.2 The objectives of the thesis ca TÔ CHAPTER 2 THEORTCAT BASTS

2.1 Titantim đioxide wll 2.1.1 Proper and siructure of titanium dioxide - 11

2.1.2, TiOa as catalyst guppOIf, co " 2 2.1.3 Synthesis of TiO, - 14 2.2 Ruflienruim cà ciinereteerrirerirerrirree ¬ )

3.2.1 Physicochemical properties and application of ruthenium 15

2.2.2 Ru-based catalysts for oxidation of alcohol LÕ 2.3 Isolated single-alom-site calalysLs 18 2.3.1 Concept and properties of isolated single-atom-site catalysts 18 2.3.2, Preparation of isolated single-alom-sile calalysls 19

2.4, Analytical methods .cccscssctsoisnnvtnsenessenseee ¬

3.4.1 X-ray điữaction (XRD) - - 21

2.3.2 Niưogen adsorption at 77 K

23.2 Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES) 24 3.3.3 X-ray photoelectron spegtrOsGOpy suasa.24 2.3.4, High-angle annular dark field scanning transmission electron microscopy (HAADF-STEM) and energy dispersive spectroscopy (EDS) 25 2.5 Aerobic oxidation of aleohol CHAPTER 3 EXPERIMENT SECTION

3.1 Preparation of catalyst

3.2 Catalyst characterization - 30

and [his is preserved aller 20h oxidalion reaction al 150 °C Furlhermore, the meal- support interaction between Ru and TiO, support becomes stronger with a decrease

in particle sive We demonstrated thal the conversion af beruzyl alcohol and product

selectivity significantly depended on the particle size Single atoms Ru on TiOz show the highest 83.62% selectivity of benzaldehyde, and it decreased when the

Ru size increased

tạ

LIST OF FIGURES

Figure 2 1 Crystal bulk structure of (a) anatase, (b) rutile, and (c) brookite

11

Figure 2 2 ‘the SMSI effect occwzing during the reduction treatment by

‘Hh The gray circles represent metallic nanoparticles, while the blue parts represent

Vigure 2 3 Biomimetic aerobie oxidation of aloohols 7

Figure 2 4 Schematic illustrate the changes of surface itve energy and specific activily per mela! alom with metal particle size and the support el

13 OM

Figure 2 5, Methods for preparmg ISAS catalyst: mass-selected soft-

landing (A) and wet chemistry (B) ào cac — ˆ

Figure 2 6 Two-dimensional representation for the derivation of the Bragg

Figure 2 7 Clasaificntin o[physisorption isotherms 23 Figure 2 8 Schematic of image formation in a STEM, showing the on-axis small brighi-field detector and the larger annular dark-field detector, pink 26

Figure 2 9, Dehydrogenation mechanism of alcchol oxidation over Pt

Figure 2 10 Evolution of geometric and electronic structures of single

atom, metal clusters, and nanoparticles -csss2tsseerseersersee.e.- 28

Figure 2 11, Reaction scheme for the benzyl alechol oxidalion 29 Figue 3 1 Schematic illustration of the preparation of RwTiO2z

igure 4 2 (@) No adsorption-desorption isotherms and (b) pore size

distribution curves 3 of different loading, Ru/li0: catalysts —-

Tipure 4 3 HAAD-STEM/RDX elememal mapping of (ai-a4) Ru/TiOs-l,

Cy -ba) RuTiOa-2, (cr-ca) Rev TiO23, and (died) Ru/TIO2-4 36

Figure 4 4 HAAD-STEM images of (a-b) RwTi0:-1, (c-d) RWTi02-2, (c- f) Ru/liOe-3, and (g-h) Ru/TiO2-4, and (i) the Ru particle size distribution of

Figure 4 5 XPS spectra of Ru 3d/C Is region of the Ru catalysts 38 Figure 4 6 XPS spectra of O Is and Ti 2p of the RWTiO2 catalysts 39

Figure 4 7 H2-TPR profiles of the four Ru/TiO2 catalysis 40

Figure 4 8 Conversion and selectivity of benzaldehyde over RWTiO2-4

Figure 4, 10, Selectivity of benzaldehyde and tumn-over frequency (TOK) of

RTA and leaching Ru/TiOz-4 catalysts - - 43

Figure 4 11, XRD spectrum of Ru/TiOz-4 anđ Ru/TiO-4 leaching catalyst

aM Figure 4 12 Effect of reaction temporature on the conversion and seleptivily [or aerobic oxidation of benzyl alechol 44

Figure 4 13 Effect of solvent on conversion and selectivity for aerobic oxidation of benzy] alcolioL -: sàn 211102 1e AS

Figure 4 14 XRD spectrum of four spent Ru/TiQ) catalysis 46

LIST OF FIGURES

Figure 2 1 Crystal bulk structure of (a) anatase, (b) rutile, and (c) brookite

11

Figure 2 2 ‘the SMSI effect occwzing during the reduction treatment by

‘Hh The gray circles represent metallic nanoparticles, while the blue parts represent

Vigure 2 3 Biomimetic aerobie oxidation of aloohols 7

Figure 2 4 Schematic illustrate the changes of surface itve energy and specific activily per mela! alom with metal particle size and the support el

13 OM

Figure 2 5, Methods for preparmg ISAS catalyst: mass-selected soft-

landing (A) and wet chemistry (B) ào cac — ˆ

Figure 2 6 Two-dimensional representation for the derivation of the Bragg

Figure 2 7 Clasaificntin o[physisorption isotherms 23 Figure 2 8 Schematic of image formation in a STEM, showing the on-axis small brighi-field detector and the larger annular dark-field detector, pink 26

Figure 2 9, Dehydrogenation mechanism of alcchol oxidation over Pt

Figure 2 10 Evolution of geometric and electronic structures of single

atom, metal clusters, and nanoparticles -csss2tsseerseersersee.e.- 28

Figure 2 11, Reaction scheme for the benzyl alechol oxidalion 29 Figue 3 1 Schematic illustration of the preparation of RwTiO2z

igure 4 2 (@) No adsorption-desorption isotherms and (b) pore size

distribution curves 3 of different loading, Ru/li0: catalysts —-

Tipure 4 3 HAAD-STEM/RDX elememal mapping of (ai-a4) Ru/TiOs-l,

Cy -ba) RuTiOa-2, (cr-ca) Rev TiO23, and (died) Ru/TIO2-4 36

Figure 4 4 HAAD-STEM images of (a-b) RwTi0:-1, (c-d) RWTi02-2, (c- f) Ru/liOe-3, and (g-h) Ru/TiO2-4, and (i) the Ru particle size distribution of

Figure 4 5 XPS spectra of Ru 3d/C Is region of the Ru catalysts 38 Figure 4 6 XPS spectra of O Is and Ti 2p of the RWTiO2 catalysts 39

CHAPTER 2 THEORTCAT BASTS

2.1 Titantim đioxide wll 2.1.1 Proper and siructure of titanium dioxide - 11

2.1.2, TiOa as catalyst guppOIf, co " 2

2.2 Ruflienruim cà ciinereteerrirerirerrirree ¬ )

3.2.1 Physicochemical properties and application of ruthenium 15

2.2.2 Ru-based catalysts for oxidation of alcohol LÕ

2.3 Isolated single-alom-site calalysLs 18

2.3.1 Concept and properties of isolated single-atom-site catalysts 18

2.3.2, Preparation of isolated single-alom-sile calalysls 19 2.4, Analytical methods .cccscssctsoisnnvtnsenessenseee ¬ 3.4.1 X-ray điữaction (XRD) - - 21 2.3.2 Niưogen adsorption at 77 K

23.2 Inductively Coupled Plasma Optical Emission Spectroscopy

3.3.3 X-ray photoelectron spegtrOsGOpy suasa.24

2.3.4, High-angle annular dark field scanning transmission electron microscopy (HAADF-STEM) and energy dispersive spectroscopy (EDS) 25

2.5 Aerobic oxidation of aleohol

3.1 Preparation of catalyst

Figure 4 7 H2-TPR profiles of the four Ru/TiO2 catalysis 40

Figure 4 8 Conversion and selectivity of benzaldehyde over RWTiO2-4

Figure 4, 10, Selectivity of benzaldehyde and tumn-over frequency (TOK) of

RTA and leaching Ru/TiOz-4 catalysts - - 43

Figure 4 11, XRD spectrum of Ru/TiOz-4 anđ Ru/TiO-4 leaching catalyst

aM Figure 4 12 Effect of reaction temporature on the conversion and seleptivily [or aerobic oxidation of benzyl alechol 44

Figure 4 13 Effect of solvent on conversion and selectivity for aerobic oxidation of benzy] alcolioL -: sàn 211102 1e AS

Figure 4 14 XRD spectrum of four spent Ru/TiQ) catalysis 46

43 Structure and morphology of catalyst aller reaction 46

CILAPTER § GENERAL CONCLUSIONS AND OUTLOOK

REFERENCES

43 Structure and morphology of catalyst aller reaction 46

CILAPTER § GENERAL CONCLUSIONS AND OUTLOOK

REFERENCES

ACKNOWLEDGMENTS

First of all, I would like to like to give my gratitude to my co-supervisors

Dr Ali Mohamed Abdel-Mageed (Surface Chemistry in Applied Catalysis, LIKAT) and Assoc Prof Dr Vu Anh Tuan (Department of Analytical Chemis HUST), for their help and support throughout imy thesis work ‘there are no words that can express my appreciation for everything that they have done for me

Tam also extremely grateful lo my colleagues in the group, Dr Jawaher Mosrati, Dr Katja Neubauer, M.Sc Evaristo Salaya, M.Sc Sebastian Lobner, Dr Mohammed Al-yusufi, Mrs Julia Schroeder They have tanght me many things in

a year

I would like to thank to Mrs Anja Simmula for ICP measurements, Mr Reinhard Rekell for nibegen adsorplion, and Dr Hanan Ata for Hz-TPR micasuroments Thank should also go to Service Depariment Analyties for XRD, and XPS analysis

1 would like to thank the RoHan project for giving me the excellent opportunity to study in Germany with full financial support

Lastly, it is impossible not to mention my family and friends, especially my parents, my brother, who gave me encouragement and emotional support along the research path

ABTRACT

‘the oxidation of alcohols to the corresponding carbonyl compounds, such

as aldehydes, ketones, and carboxylic acids, has received the most attention These

compounds are versatile and valuable intermediates in manufacturing pharmaccuticals, perfumes, and flavorings [1] The catalytic performance of metal nanoparticles in the oxidation of alcohol reactions can be influcnced by many factors, including the size and shape of melal clusters and nanoparticles,

promoters, and interactions between supports and active sites Ru has attracted considerable interest in catalysis not only because of its relatively low cost

compared to commonly studied and industrially applied noble metals such as Au,

Tt, Pd, but also due to its tunability by different support effects, especially in

combination with T1O: Here, we aim to at identification of the role of Ru

janoparticle versus to the single atoms for catalytic activity and product selectrvity

in the aerobic oxidation of benzyl alechol

Ru/TiOy catalysis were prepared using a wetness impregnation method The

Ru particle size was controled by varing the Ru loading from 0.2 to 3.0 wi% The materials were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (MPS), high-angle annular dark field scanning transmission electron

amieroscopy (HAADF-STHM) and energy dispersive spectroscopy (EDS), Hạ-

temperature-programmed-reduction (IPR) The state oxidation of Ru on ‘TiO: support is metallic Ru and Ru* for the fresh catalyst and Ru‘* for the spent catalysl The HAAD-STEM resulls show the highly disparsed Ru on the supporl,

1

43 Structure and morphology of catalyst aller reaction 46

CILAPTER § GENERAL CONCLUSIONS AND OUTLOOK

REFERENCES

and [his is preserved aller 20h oxidalion reaction al 150 °C Furlhermore, the meal- support interaction between Ru and TiO, support becomes stronger with a decrease

in particle sive We demonstrated thal the conversion af beruzyl alcohol and product

selectivity significantly depended on the particle size Single atoms Ru on TiOz show the highest 83.62% selectivity of benzaldehyde, and it decreased when the

Ru size increased

tạ

43 Structure and morphology of catalyst aller reaction 46

CILAPTER § GENERAL CONCLUSIONS AND OUTLOOK

REFERENCES

CHAPTER 2 THEORTCAT BASTS

2.1 Titantim đioxide wll 2.1.1 Proper and siructure of titanium dioxide - 11

2.1.2, TiOa as catalyst guppOIf, co " 2

2.2 Ruflienruim cà ciinereteerrirerirerrirree ¬ )

3.2.1 Physicochemical properties and application of ruthenium 15

2.2.2 Ru-based catalysts for oxidation of alcohol LÕ

2.3 Isolated single-alom-site calalysLs 18

2.3.1 Concept and properties of isolated single-atom-site catalysts 18

2.3.2, Preparation of isolated single-alom-sile calalysls 19 2.4, Analytical methods .cccscssctsoisnnvtnsenessenseee ¬ 3.4.1 X-ray điữaction (XRD) - - 21 2.3.2 Niưogen adsorption at 77 K

23.2 Inductively Coupled Plasma Optical Emission Spectroscopy

3.3.3 X-ray photoelectron spegtrOsGOpy suasa.24

2.3.4, High-angle annular dark field scanning transmission electron microscopy (HAADF-STEM) and energy dispersive spectroscopy (EDS) 25

2.5 Aerobic oxidation of aleohol

3.1 Preparation of catalyst

43 Structure and morphology of catalyst aller reaction 46

CILAPTER § GENERAL CONCLUSIONS AND OUTLOOK

REFERENCES

and [his is preserved aller 20h oxidalion reaction al 150 °C Furlhermore, the meal- support interaction between Ru and TiO, support becomes stronger with a decrease

in particle sive We demonstrated thal the conversion af beruzyl alcohol and product

selectivity significantly depended on the particle size Single atoms Ru on TiOz show the highest 83.62% selectivity of benzaldehyde, and it decreased when the

Ru size increased

tạ

and [his is preserved aller 20h oxidalion reaction al 150 °C Furlhermore, the meal- support interaction between Ru and TiO, support becomes stronger with a decrease

in particle sive We demonstrated thal the conversion af beruzyl alcohol and product

selectivity significantly depended on the particle size Single atoms Ru on TiOz show the highest 83.62% selectivity of benzaldehyde, and it decreased when the

Ru size increased

tạ

LIST OF FIGURES

Figure 2 1 Crystal bulk structure of (a) anatase, (b) rutile, and (c) brookite

11

Figure 2 2 ‘the SMSI effect occwzing during the reduction treatment by

‘Hh The gray circles represent metallic nanoparticles, while the blue parts represent

Vigure 2 3 Biomimetic aerobie oxidation of aloohols 7

Figure 2 4 Schematic illustrate the changes of surface itve energy and specific activily per mela! alom with metal particle size and the support el

13 OM

Figure 2 5, Methods for preparmg ISAS catalyst: mass-selected soft-

landing (A) and wet chemistry (B) ào cac — ˆ

Figure 2 6 Two-dimensional representation for the derivation of the Bragg

Figure 2 7 Clasaificntin o[physisorption isotherms 23 Figure 2 8 Schematic of image formation in a STEM, showing the on-axis small brighi-field detector and the larger annular dark-field detector, pink 26

Figure 2 9, Dehydrogenation mechanism of alcchol oxidation over Pt

Figure 2 10 Evolution of geometric and electronic structures of single

atom, metal clusters, and nanoparticles -csss2tsseerseersersee.e.- 28

Figure 2 11, Reaction scheme for the benzyl alechol oxidalion 29 Figue 3 1 Schematic illustration of the preparation of RwTiO2z

igure 4 2 (@) No adsorption-desorption isotherms and (b) pore size

distribution curves 3 of different loading, Ru/li0: catalysts —-

Tipure 4 3 HAAD-STEM/RDX elememal mapping of (ai-a4) Ru/TiOs-l,

Cy -ba) RuTiOa-2, (cr-ca) Rev TiO23, and (died) Ru/TIO2-4 36

Figure 4 4 HAAD-STEM images of (a-b) RwTi0:-1, (c-d) RWTi02-2, (c- f) Ru/liOe-3, and (g-h) Ru/TiO2-4, and (i) the Ru particle size distribution of

Figure 4 5 XPS spectra of Ru 3d/C Is region of the Ru catalysts 38 Figure 4 6 XPS spectra of O Is and Ti 2p of the RWTiO2 catalysts 39

and [his is preserved aller 20h oxidalion reaction al 150 °C Furlhermore, the meal- support interaction between Ru and TiO, support becomes stronger with a decrease

in particle sive We demonstrated thal the conversion af beruzyl alcohol and product

selectivity significantly depended on the particle size Single atoms Ru on TiOz show the highest 83.62% selectivity of benzaldehyde, and it decreased when the

Ru size increased

tạ

Figure 4 7 H2-TPR profiles of the four Ru/TiO2 catalysis 40

Figure 4 8 Conversion and selectivity of benzaldehyde over RWTiO2-4

Figure 4, 10, Selectivity of benzaldehyde and tumn-over frequency (TOK) of

RTA and leaching Ru/TiOz-4 catalysts - - 43

Figure 4 11, XRD spectrum of Ru/TiOz-4 anđ Ru/TiO-4 leaching catalyst

aM Figure 4 12 Effect of reaction temporature on the conversion and seleptivily [or aerobic oxidation of benzyl alechol 44

Figure 4 13 Effect of solvent on conversion and selectivity for aerobic oxidation of benzy] alcolioL -: sàn 211102 1e AS

Figure 4 14 XRD spectrum of four spent Ru/TiQ) catalysis 46