Mechanochemically assisted synthesis of zeolite catalysts for biomass conversion

Abstract

I would like to thank Prof. Sarah Larsen and Prof. Edward Gillan for being the best research advisors and giving me the opportunity to work in their lab. I truly enjoyed being their student, and I learned a lot from their insight and advice how to be a successful research scientist. Thanks to both of them for their patience and direction throughout my graduate education experience. I would like to thank former and current graduate students in Larsen and Gillan research group for their support and advice. I learned a lot from them how to use the instruments and software in the lab and how to be a successful graduate student, and I really appreciate the time we spent together in the lab. Last but not least I would like to thank the department of chemistry and graduate college at The University of Iowa for the financial support and for giving me the opportunity to be one of their Hawkeye graduate students. It is great to be Hawkeye. Thanks iv ABSTRACT Recently, there has been growing interest in the green synthesis of zeolite (aluminosilicate) materials using solvent-free synthesis methods. Solid starting materials are typically ground for a period of time followed by thermal heating to synthesize crystalline ZSM-5 zeolite. These studies generally have focused on products formed after the thermal heating. However, very little is known about the reaction intermediates formed during the mechanochemical pre-reaction grinding step and how the pre-reaction impacts the subsequent synthetic success. In this study, the mechanochemical approach used to synthesize ZSM-5 and mordenite zeolite was investigated. Two types of solvent-free synthesis methods were investigated; templated solvent-free synthesis, and template-free and solvent-free synthesis. The effect of grinding time was investigated first to find the optimal grinding time that initiates pre-reactions between the starting materials. Controlled experiments were used to monitor chemical and physical changes occuring during the grinding step. Subsequently, the effect of different synthesis conditions such as time, temperature, template, SiO2/Al2O3, and Na2O/Al2O3 ratios, and different precursors were studied using the optimal grinding time. Both manual (mortar and pestle) and ball mill (FTS 1000) grinding were used in this study. The synthesized products were characterized using XRD, BET nitrogen adsorption, SEM, and ICP-OES. Finally, selected single-phase synthesized zeolite materials were evaluated for their catalytic performance in biomass conversion process of cellulose and glucose to useful chemicals such as hydroxymethylfurfural (HMF).