TY - JOUR
T1 - Comparison of kinetics, activity and stability of Ni/HZSM-5 and Ni/Al 2O3-HZSM-5 for phenol hydrodeoxygenation
AU - Zhao, Chen
AU - Kasakov, Stanislav
AU - He, Jiayue
AU - Lercher, Johannes A.
N1 - Funding Information:
This work was financially supported by the Technische Universität München in the framework of the European Graduate School for Sustainable Energy.
PY - 2012/12
Y1 - 2012/12
N2 - We have investigated the detailed kinetics of phenol hydrodeoxygenation in liquid aqueous medium over Ni supported on HZSM-5 or HZSM-5 with 19.3 wt.% γ-Al2O3 binder. The individual reaction steps on two Ni catalysts followed the rate order r1 (phenol hydrogenation) < r2 (cyclohexanone hydrogenation) < r3 (cyclohexanol dehydration) ≪ r4 (cyclohexene hydrogenation), so that phenol hydrogenation was the rate determining step. As Ni/Al2O 3-HZSM-5 showed up to five times higher catalytic activity for phenol hydrogenation than Ni/HZSM-5, it also delivered higher rates for overall phenol hydrodeoxygenation, verified by both the kinetic study monitored by GC and in situ IR spectroscopy to trace the product concentrations. Under the present conditions, Ni leaching was almost negligible from Ni/Al2O 3-HZSM-5 after 90 h. The HZSM-5 support was stable, but the Al 2O3-HZSM-5 support lost 7 wt.%. The catalytic activity gradually decreased when catalyst was recovered and reused, mainly due to Ni particle sintering tracked by transmission electron microscopy. The change of acid sites on the fresh and used catalysts monitored by IR of adsorbed pyridine demonstrated that Bronsted acid sites of HZSM-5 could be irreversibly transformed to Lewis acid sites during calcination.
AB - We have investigated the detailed kinetics of phenol hydrodeoxygenation in liquid aqueous medium over Ni supported on HZSM-5 or HZSM-5 with 19.3 wt.% γ-Al2O3 binder. The individual reaction steps on two Ni catalysts followed the rate order r1 (phenol hydrogenation) < r2 (cyclohexanone hydrogenation) < r3 (cyclohexanol dehydration) ≪ r4 (cyclohexene hydrogenation), so that phenol hydrogenation was the rate determining step. As Ni/Al2O 3-HZSM-5 showed up to five times higher catalytic activity for phenol hydrogenation than Ni/HZSM-5, it also delivered higher rates for overall phenol hydrodeoxygenation, verified by both the kinetic study monitored by GC and in situ IR spectroscopy to trace the product concentrations. Under the present conditions, Ni leaching was almost negligible from Ni/Al2O 3-HZSM-5 after 90 h. The HZSM-5 support was stable, but the Al 2O3-HZSM-5 support lost 7 wt.%. The catalytic activity gradually decreased when catalyst was recovered and reused, mainly due to Ni particle sintering tracked by transmission electron microscopy. The change of acid sites on the fresh and used catalysts monitored by IR of adsorbed pyridine demonstrated that Bronsted acid sites of HZSM-5 could be irreversibly transformed to Lewis acid sites during calcination.
KW - AlO binder
KW - Dealumination
KW - Phenol hydrodeoxygenation
KW - React IR
UR - http://www.scopus.com/inward/record.url?scp=84868713121&partnerID=8YFLogxK
U2 - 10.1016/j.jcat.2012.08.017
DO - 10.1016/j.jcat.2012.08.017
M3 - Article
AN - SCOPUS:84868713121
SN - 0021-9517
VL - 296
SP - 12
EP - 23
JO - Journal of Catalysis
JF - Journal of Catalysis
ER -