SYNTHESIS AND CHARACTERIZATION OF NEW METAL-CARBON CATALYSTS FOR HYDROGENATION OF D-GLUCOSE LIU JIAJIA NATIONAL UNIVERSITY OF SINGAPORE 2010 SYNTHESIS AND CHARACTERIZATION OF NEW METAL-CARBON CATALYSTS FOR HYDROGENATION OF D-GLUCOSE LIU JIAJIA (M.Eng, Tianjin University) A THESIS SUBMITTED FOR THE DEGREE OF DOCTOR OF PHILOSOPHY DEPARTMENT OF CHEMICAL AND BIOMOLECULAR ENGINEERING NATIONAL UNIVERSITY OF SINGAPORE 2010 Acknowledgement Acknowledgement I am heartily thankful to my supervisor, Assoc. Prof. Zhao X. S., George, whose constant encouragement, invaluable guidance, patience and support throughout the whole period of my PhD candidature. I would also like to thank Assoc. Prof. Zhao for his guidance on writing scientific papers including this PhD thesis. In addition, I want to express my sincerest appreciation to the Department of Chemical and Biomolecular Engineering for offering me the chance to study at NUS with a scholarship. It’s my pleasure to work with a group of brilliant, warmhearted and lovely people. Wish all my lab mates go well with their work. Particular acknowledgement goes to Dr. Liu Tao, Mr. Chia Phai Ann, Mr. Shang Zhenhua, Dr. Yuan Zeliang, Mr. Mao Ning, Mr. Liu Zhicheng, Dr. Rajarathnam D., Madam Chow Pek Jaslyn, Mdm Fam Hwee Koong Samantha, Ms Lee Chai Keng, Ms Tay Choon Yen, Mr. Toh Keng Chee, Mr. Chun See Chong, Ms. Ng Ai Mei, Ms. Lum Mei Peng Sharon, and Ms. How Yoke Leng Doris for their kind supports. I thank my parents and my husband. It is no exaggeration to say that I could not complete the PhD work without their generous help, boundless love, encouragement and support. Lastly, I offer my regards and blessing to all of those who supported me in any respect during the completion of the project. i Table of Contents Table of Contents Acknowledgement .......................................................................................................... i Table of Contents .......................................................................................................... ii Summary ..................................................................................................................... v Nomenclature ............................................................................................................. viii List of Tables ................................................................................................................ ix List of Figures ............................................................................................................... x Chapter 1. Introduction .................................................................................................. 1 1.1 Hydrogenation reactions ......................................................................... 1 1.2 Importance of hydrogenation of D-glucose ............................................ 3 1.3 Catalysts for hydrogenation reactions ..................................................... 3 1.4 Carbon-supprted catalysts for hydrogenation reactions .......................... 6 1.5 Recent advance on template approach to preparing novel porous carbons and catalysts ..................................................................................... 7 1.6 Objective of project ................................................................................. 8 1.7 Structure of thesis ................................................................................... 9 Chapter 2. Literature review ........................................................................................ 11 2.1 Hydrogenation reactions ....................................................................... 11 2.2 Catalysts in hydrogenation reactions .................................................... 13 2.3 Hydrogenation of D-glucose ................................................................. 37 2.4 Porous carbon as a catalyst support ...................................................... 43 Chapter 3. Experimental section .................................................................................. 59 3.1 Chemicals .............................................................................................. 59 3.2 Synthesis methods ................................................................................. 60 ii Table of Contents 3.3 Characterization techniques .................................................................. 63 3.4 Evaluation of catalytic properties ......................................................... 75 Chapter 4. Ru nanoparticles embedded in templated porous carbon and catalytic performance in D-glucose hydrogenation ................................................... 77 4.1 Introduction ........................................................................................... 77 4.2 Characterization of Ru nanoparticles catalysts ..................................... 77 4.3 Catalytic properties ............................................................................... 84 4.4 Summary ............................................................................................... 91 Chapter 5. Bimetallic Ru-Cu nanoparticles sandwiched in porous carbon ................. 92 5.1 Introduction ........................................................................................... 92 5.2 Characterization of bimetallic Ru-Cu catalysts .................................... 94 5.3 Catalytic properties ............................................................................. 106 5.4 Summary ............................................................................................. 108 Chapter 6. Ruthenium nanoparticles embedded in mesoporous carbon fibers ......... 109 6.1 Introduction ......................................................................................... 109 6.2 Characterization of Ru nanoparticles catalysts ................................... 111 6.3 Catalytic properties ............................................................................. 122 6.4 Summary ............................................................................................. 126 Chapter 7. Kinetics of the catalytic hydrogenation of D-glucose over bimetallic Ru- Cu carbon catalyst ..................................................................................... 127 7.1 Introduction ......................................................................................... 127 7.2 Kinetics of the hydrogenation of D-glucose ....................................... 128 7.3 Modeling results of kinetics and mechanism ...................................... 132 7.4 Summary ............................................................................................. 135 Chapter 8. Conclusions and recommendations ......................................................... 137 iii Table of Contents 8.1 Conclusions ......................................................................................... 137 8.2 Recommendations ............................................................................... 139 References ................................................................................................................... 140 Appendix ..................................................................................................................... 162 iv Summary Summary Catalytic hydrogenation is a process for the reduction of chemical substances, and has found numerous applications in the chemical and petrochemical industries. The hydrogenation reaction can be carried out heterogeneously or homogeneously. The heterogeneous catalysts are in generally a metal supported on a solid that are prepared by using conventional methods, such as impregnation followed by hydrogen reduction. Such supported catalysts suffer from a number of problems, such as aggregation and leaching of the metal particles. Thus, new methods that afford the preparation of catalytically highly active, chemically and thermally stable, technically reusable, and cost-effective are highly desirable. In this thesis work, the template strategy was employed to prepare new heterogeneous catalysts. The catalysts were characterized using a number of techniques, such as extended X-ray absorption spectroscopy (XAS) and chemisorption of hydrogen and carbon monoxide. The catalytic properties of the catalysts were evaluated using the hydrogenation of D-glucose in a batch reactor. First, ruthenium nanoparticles embedded in the pore walls of templated carbon (denoted RuC) were prepared by using H-form zeolite Y and mesoporous silica SBA- 15 as templates. Compared with other ruthenium catalysts prepared using conventional methods, the RuC catalysts prepared using the template method exhibited a significantly improved catalytic performance because of the unique structure of the RuC catalysts. Second, bimetallic ruthenium-copper (Ru-Cu) nanoparticles embedded in the pore walls of mesoporous carbon were prepared. The presence of bimetallic entities was supported by the characterization data of both Ru LIII-edge and Cu K-edge X-ray v Summary absorption. It was observed that additional active sites were created because of the spillover of H from Ru to Cu at low Cu contents while three-dimensional islands of segregated metallic Cu phase covering the surface of Ru nanoparticles appeared at high Cu contents. Third, alumina microfibers were also used as templates to prepare Ru nanoparticles embedded in mesoporous carbon fibers. In comparison with Ru nanoparticles supported on other carbon materials (e.g., multi-walled