Understanding the impact of aluminum oxide binder on Ni/HZSM-5 for phenol hydrodeoxygenation

Authors: Chen Zhao, Yanzhe Yu, Andreas Jentys, Johannes A. Lercher

Abstract:
The properties of supported Ni particles on HZMS-5 and Al₂O₃-HZSM-5 were comparably investigated by diverse characteristic techniques. Ni/Al₂O₃-HZSM-5 had at least three times higher concentrations of accessible Ni atoms (average diameter Ni⁰: 8.8 nm) compared to Ni/HZSM-5 (average diameter Ni0: 35 nm), which are consistently evidenced by TEM and XRD as well as H₂ chemisorption and IR spectra of adsorbed CO. The Ni nanoparticles interacted strongly with the binder through the interaction between NiO and Al₂O₃, explored by the combined extended X-ray absorption fine structure (EXAFS), X-ray absorption near edge structure (XANES), and H₂ temperature-programmed reduction (TPR) techniques. The Brønsted acid sites on two supports probed by IR of adsorbed pyridine were similar, but Lewis acid sites contributed by the γ-Al₂O₃ were more abundant on Al₂O₃-HZSM-5. The acid sites of the two catalysts responded differently to metal incorporation and subsequent treatments, reflecting changes in Al environments illuminated by 27Al MAS NMR. In situ IR spectra of adsorbed species demonstrates that Al₂O₃-HZSM-5 has higher adsorption capacity for phenol, cyclohexanone, and cyclohexanol due to stronger adsorption of these compounds on the γ-Al₂O₃ binder. 

Keywords:
Al₂O₃ binder
²⁷Al and ²⁹Si MAS NMR
EXAFS
XANES

Published in: Applied Catalysis B: Environmental (Volumes 132–133, Pages 1-552, 27 March 2013)

Publisher: Elsevier  

ISSN Information: 0926-3373

Understanding the impact of aluminum oxide binder on Ni/HZSM-5 for phenol hydrodeoxygenation

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