Synthesis, Physicochemical Characterization, and Catalytic Evaluation of Fe3+-Containing SSZ-70 Zeolite

Whereas one-dimensional, 10-membered ring zeolites are typically used for hydroisomerization, Fe3+-containing SSZ-70 (Fe-SSZ-70) shows remarkable isomerization selectivity for a zeolite containing 12- and partially blocked 14-membered rings, in addition to 10-membered rings. Fe-SSZ-70 was compared t...

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Published inACS catalysis Vol. 12; no. 11; pp. 6464 - 6477
Main Authors Lew, Christopher M., Chen, Cong-Yan, Long, Gary J., Grandjean, Fernande, Ichimura, Andrew S., Xie, Dan, Grosso-Giordano, Nicolás A., Chakarawet, Khetpakorn, Lacheen, Howard S., Jensen, Kurt O., Martinez, Abraham, Katz, Alexander, Zhan, Bi-Zeng, Zones, Stacey I.
Format Journal Article
LanguageEnglish
Published American Chemical Society 03.06.2022
Subjects
ferrosilicate zeolite
SSZ-70
hydrocracking
hydroisomerization
cracking
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Summary:Whereas one-dimensional, 10-membered ring zeolites are typically used for hydroisomerization, Fe3+-containing SSZ-70 (Fe-SSZ-70) shows remarkable isomerization selectivity for a zeolite containing 12- and partially blocked 14-membered rings, in addition to 10-membered rings. Fe-SSZ-70 was compared to Al3+-containing SSZ-70 (Al-SSZ-70) in constraint index and n-decane hydrocracking tests. Fe-SSZ-70 exhibited a 74% total isomer yield (64% yield of monobranched isomers and 10% cracking yield) at 85% conversion compared to 49% total isomer yield (41% yield of monobranched isomers and 36% cracking yield) for Al-SSZ-70 at the same conversion. The selectivity to isomerization is attributed to the weaker acid strength of Fe-SSZ-70 over Al-SSZ-70. Fe-SSZ-70 was directly synthesized with Fe3+ isomorphously substituted in tetrahedral positions. The coordination environment of the Fe3+ was characterized using Mössbauer, electron paramagnetic resonance, and diffuse reflectance UV–vis spectroscopies. The physicochemical properties were further probed with inductively coupled plasma atomic emission spectroscopy, temperature-programmed desorption of isopropylamine, and nitrogen adsorption–desorption. The Fe3+ was tetrahedrally coordinated in the as-made materials and became partially octahedrally coordinated upon calcination; enough Fe3+ remained in the framework after calcination for Fe-SSZ-70 to remain catalytically active.
ISSN:2155-5435
2155-5435
DOI:10.1021/acscatal.2c01361