456728 A Liquid Phase Spectroscopic Study of the Effect of Liquid Water on Acid Sites of NaY

Wednesday, November 16, 2016: 5:15 PM
Imperial B (Hilton San Francisco Union Square)
Bingjun Xu, Center for Catalytic Science and Technology, Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, DE and Nicholas Gould, Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, DE

Liquid phase heterogeneously catalyzed reactions are ubiquitous, especially in biomass upgrade processes. However, establishing structure-activity relations for liquid phase reactions is challenging because the effect of solvent is poorly understood. Spectroscopy of adsorbed probe molecules like pyridine have been widely used to characterize catalyst acidity, and these experiments have almost exclusively been conducted in vacuum. This motivates a need for liquid phase probe molecule characterization, both to more accurately reflect reaction conditions, and to study the effect of solvent. Attenuated Total Reflection Fourier Transform Infrared spectroscopy (ATR-FTIR) was used to detect pyridine adsorbed on sodium faujasite (NaY) in water. The slow accumulation of pyridinium on NaY in water was observed in the ATR cell, suggesting water promotes Brønsted acidity on NaY. The accumulation of protonated pyridine in NaY pores led to the question of whether NaY can support Brønsted acid catalyzed pathways in protic solvent. The Brønsted catalyzed ring opening of 2,5-dimethylfuran (DMF) to 2,5-hexanedione is not active on NaY in water, which is attributed to the lack of basicity of DMF. A weaker base than pyridine, deuterated acetonitrile, adsorbed on NaY in water demonstrated no Brønsted character.

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