Promotion of protolytic pentane conversion on H-MFI zeolite by proximity of extra-framework aluminum oxide and Brønsted acid sites

Journal Article · Fri Feb 01 04:00:00 EST 2019 · Journal of Catalysis

DOI:https://doi.org/10.1016/j.jcat.2019.01.006· OSTI ID:1643789

Zhang, Yang ^[1]; Zhao, Ruixue ^[1]; Sanchez-Sanchez, Maricruz ^[1]; Haller, Gary L. ^[1]; Hu, Jian Z. ^[2]; Bermejo-Deval, Ricardo ^[3]; Liu, Yue ^[1]; Lercher, Johannes A. ^[2]

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1. Technische Universitat Munchen
2. BATTELLE (PACIFIC NW LAB)
3. Technische Universitat Munich

The activity of strong Brønsted acid sites in H-MFI zeolites for pentane cracking and dehydrogenation is enhanced by the presence of extra-framework aluminum in spatial proximity. The steric proximity of these two sites is deduced from the perturbation of OH groups on extra-framework aluminum oxide by pyridine or pentane adsorbed on Brønsted acid sites manifested in the IR spectra. The turnover frequencies of overall cracking and dehydrogenation on such sites are about 50 and 80 times higher than on isolated strong Brønsted acid sites. While pentane does not adsorb stronger, the site pair stabilizes cracking and dehydrogenation transition states mainly via increasing the activation entropy. This is interpreted as a later transition state for the cracking and dehydrogenation. The results suggest that controlled steaming can be used to enhance catalytic activity of zeolite Brønsted acid sites.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 1643789
• Report Number(s): PNNL-SA-154782
• Journal Information: Journal of Catalysis, Journal Name: Journal of Catalysis Vol. 370
• Country of Publication: United States
• Language: English