Acid Catalysis over Low-Silica Faujasite Zeolites
- Univ. of Minnesota, Minneapolis, MN (United States)
- Univ. of Minnesota, Minneapolis, MN (United States); Dalian Univ. of Technology (China)
- Argonne National Lab. (ANL), Lemont, IL (United States). Advanced Photon Source (APS)
- California Institute of Technology (CalTech), Pasadena, CA (United States)
- Johns Hopkins Univ., Baltimore, MD (United States)
- Univ. of Minnesota, Minneapolis, MN (United States); Johns Hopkins Univ., Baltimore, MD (United States)
We report low-silica faujasite (FAU) zeolites (with Si/Al ratio of ca. 1.2–1.8) sustain framework integrity and porosity upon moderate ion exchange (0.01 M NH4NO3 solution for 1 h at ambient temperature), which introduces two kinds of protons, distinctive in reactivity and coordination to the zeolite framework, within supercages (HSUP). Moderate ion exchange limited within supercages transpires while maintaining full occupancy of Na+ cations within associated sodalite cages; this in turn helps stabilize the framework of low-silica H-FAU zeolites. Protons located on site II (H3630) and site III (H3650) within supercages on low-silica FAU zeolites can be classified and enumerated by virtue of infrared spectroscopy, providing an opportunity to compare reactivities of these distinct protons for monomolecular protolytic reactions of propane. Protons on site II exhibit prominently higher reactivity for monomolecular propane dehydrogenation and cracking than protons on site III. Low-silica proton-form FAU zeolites (zeolite X) upon moderate ion exchange possess protons on site III that are unavailable on high-silica FAU zeolites (zeolite Y) and limit ion exchange within supercages, providing unprecedented high-temperature structural and chemical stability (>773 K) and enabling their application as solid-acid catalysts.
- Research Organization:
- Argonne National Laboratory (ANL), Argonne, IL (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES). Chemical Sciences, Geosciences & Biosciences Division; National Science Foundation (NSF); USDOE Office of Science (SC), Basic Energy Sciences (BES). Scientific User Facilities Division
- Grant/Contract Number:
- AC02-06CH11357; SC0001004; FG02-12ER16362; SC00019028; DMR-1420013
- OSTI ID:
- 1969740
- Journal Information:
- Journal of the American Chemical Society, Vol. 144, Issue 21; ISSN 0002-7863
- Publisher:
- American Chemical Society (ACS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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