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Presenter: Veronika Dubovis

Faculty Sponsor: Friederike C. Jentoft

School: UMass Amherst

Research Area: Chemical and Biomolecular Engineering

Session: Poster Session 4, 2:15 PM - 3:00 PM, Auditorium, A44

ABSTRACT

Olefins serve as fundamental building blocks in the chemical industry and are synthesized by various methods, each with its own drawbacks and limitations. Therefore, aldol fission chemistry offers an alternative catalytic pathway by converting oxygen-rich carbonyl compounds directly into olefins without requiring reduction steps. This project aims at studying how catalyst pore structure and substrate size influence aldol fission selectivity using zeolite catalysts. Batch aldol reactions between aldehydes and 3-pentanone were conducted utilizing Brønsted-acidic zeolites with different frameworks, including BEA, FAU, and MWW. Benzaldehyde, acetophenone, and propiophenone were chosen as substrates to study increasing molecular size. Reaction products were analyzed using gas chromatography with flame ionization and mass spectrometric detection to determine substrate conversion, fission yield, and selectivity. Benzaldehyde showed high fission selectivity and yield in combination with BEA catalysts, consistent with prior literature. For acetophenone, the HY zeolite showed significantly higher fission selectivity and yield than MCM-22, indicating that larger pore systems better stabilize reaction intermediates required for carbon–carbon bond cleavage. In contrast, MCM-22 primarily produced self-condensation products, likely due to its pocket-like external active sites which are more accessible for bulkier substrates. Propiophenone produced only condensation products with all catalysts tested, suggesting that its size restricts access to internal catalytic sites of the chosen catalysts. Ongoing work includes investigating SBA-15, a mesoporous catalyst with large channels and few micropores, which improves molecular diffusion and access to active sites. The catalyst’s structure may be ideal for accommodating large substrates like acetophenone and propiophenone to enable fission production.