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 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.
C. M. Lew and C. Y. Chen and G. J. Long and F. Grandjean and A. S. Ichimura and D. Xie and N. A. Grosso-Giordano and K. Chakarawet and H. S. Lacheen and K. O. Jensen and A. Martinez and A. Katz and B. Z. Zhan and S. I. Zones, "Synthesis, Physicochemical Characterization, and Catalytic Evaluation of Fe³⁺-Containing SSZ-70 Zeolite," ACS Catalysis, vol. 12, no. 11, pp. 6464 - 6477, American Chemical Society, Jun 2022.
The definitive version is available at https://doi.org/10.1021/acscatal.2c01361
Keywords and Phrases
Cracking; Ferrosilicate Zeolite; Hydrocracking; Hydroisomerization; SSZ-70
International Standard Serial Number (ISSN)
Article - Journal
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03 Jun 2022