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Published December 20, 2021 | Supplemental Material
Journal Article Open

Sulfonic Acid-Functionalized Zeolite Beta: Bronsted Acid Catalysts for Reactions Involving Liquid Water

Abstract

The utility of zeolites in biomass upgrading reactions can be limited in cases where stronger Bronsted acidity and/or hydrophobicity are required for effective catalysis. While sulfonated solids/sulfonic acid catalysts can be used in such cases, they forego the advantageous effects of confinement that are afforded by zeolites. Here, acidity, hydrophobicity, and confinement are integrated into a solid material by functionalizing the intrapore voids of zeolite Beta with phenethyl-sulfonic acid sites (PE-Betas). These PE-Betas, along with conventional H-Betas, mesoporous phenethyl-sulfonic acid-functionalized SiO₂ gel (PE-SiO₂), and commercial sulfonic acid catalysts (para-toluenesulfonic acid, Nafion NR50) are evaluated in the hydroxyalkylation/alkylation reaction of 2-methylfuran with acetone. The PE-Betas show superior turnover numbers (TON) due to the combination of high acid site strength and hydrophobicity that arises from the confined PE groups. Further, the hydrophobicity and TON over PE-Betas are invariant with acid site density, showing that these materials effectively decouple the active site density–hydrophilicity relationship that is a fundamental limitation of conventional zeolites. These sulfonic acid-functionalized zeolites represent a distinct class of water-tolerant, strong Bronsted acid catalysts that may be well suited for a wide range of biomass upgrading reactions that generate stoichiometric amounts of liquid water.

Additional Information

© 2021 American Chemical Society. Received: September 17, 2021; Revised: November 19, 2021; Published: December 6, 2021. We are delighted to contribute to this special issue that honors Professor James A. Dumesic. In addition to being a pioneer in heterogeneous catalysis for sustainability, Jim has been an excellent model of a consummate professor. His scientific contributions coupled with his friendly demeanor (that includes his great sense of humor) inspire us and others to emulate his professionalism. Jim, we thank you for being a leader in our field of research. The authors gratefully acknowledge Dr. Sonjong Hwang for his helpful insight on CPMAS NMR analysis and Dr. Donglong Fu for acquiring TGA profiles for porosity analysis. The authors also thank members of the CCEI for helpful technical discussions. This work was supported as part of the Catalysis Center for Energy Innovation (CCEI), an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under award number DE-SC0001004. The authors declare no competing financial interest.

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Created:
August 22, 2023
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October 23, 2023