Conversion of Bioethanol to 1,3-Butadiene for the Manufacture of Green Tires
Department: Chemical and Biomolecular Engineering
Advisor: Israel Wachs
Abundant and low-cost shale gas has replaced naphtha as the feedstock of choice for ethylene production and has led to a shortage of 1,3-butadiene (1,3-BD), a critical intermediate for the manufacture of synthetic rubber.1-3 The constrained 1,3-BD supply has triggered significant price fluctuations as well as interest in on-purpose 1,3-BD production.1-3 Cellulosic ethanol is a sustainable feedstock quickly becoming mainstream and its conversion into 1,3-BD significantly reduces lifecycle greenhouse gas emissions when compared to petroleum-derived 1,3-BD.4 Basic and acidic supported metal oxides show promise for the conversion of ethanol to 1,3-BD in a single reactor.5,6 However, relatively few detailed mechanistic studies have been reported and the reaction over SiO2-supported ZnO-ZrO2 catalysts remains poorly understood.
To determine the reaction network for the conversion of ethanol to 1,3-BD over ZnO-ZrO2/SiO2 and the functions of the catalytic components, ethanol temperature-programmed surface reaction spectroscopy (TPSR) was applied to ZrO2/SiO2, ZnO/SiO2, and ZnO-ZrO2/SiO2 catalysts. Ethanol-TPSR over ZrO2/SiO2 showed that ZrO2 both dehydrogenates ethanol to acetaldehyde and couples C2 molecules to form C4 products, with diethyl ether (DEE) formation reflecting the presence of weak surface acid sites. Ethanol-TPSR over ZnO/SiO2 showed dehydrogenation to acetaldehyde as the predominant reaction pathway with faster dehydrogenation kinetics than ZrO2/SiO2. Ethanol-TPSR over ZnO-ZrO2/SiO2 indicated a synergistic ZnO-ZrO2 interaction that dramatically increases the catalytic activity and selectivity for 1,3-BD and suppresses formation of DEE from acid sites. The delayed desorption of crotonaldehyde relative to 1,3-BD suggested that the commonly accepted reaction mechanism5 with crotonaldehyde as a reaction intermediate does not operate for this catalyst system.
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About Brianna Ruggiero:
Brianna Ruggiero is a junior at Lehigh University pursuing a B.S. in Chemical Engineering. Brianna has worked with Dr. Israel E. Wachs since May 2016 and was named a Clare Boothe Luce Research Scholar, an award that highlights the participation of women in the sciences and engineering, and it recognizes high achieving scholars who possess a scientific curiosity carried out through research. At the annual 2016 conference of the American Institute of Chemical Engineers in San Francisco, California, Brianna placed 3rd in the student poster competition. With a strong interest in catalysis and reaction engineering, Brianna plans to pursue her PhD in Chemical Engineering following graduation. Aside from her studies, Brianna is a member of the Society of Women Engineers, a Lehigh Mountaintop Project Participant, a manager at Lehigh’s Taylor Gym Athletics, and a volunteer at the local animal shelter AWSOM.