Palladium (Pd0) Loading-Controlled Catalytic Activity and Selectivity for Chlorophenol Hydrodechlorination and Hydrosaturation

Reductive catalysis by zero-valent palladium nanoparticles (Pd0NPs) has emerged as an efficient strategy for promoting the detoxification of chlorophenols (CPs) via hydrogenation. Most studies achieved hydrodechlorination of CP to phenol for detoxification, but it requires considerably high energy i...

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Bibliographic Details
Published in:Environmental science & technology 2022-04, Vol.56 (7), p.4447-4456
Main Authors: Luo, Yi-Hao, Cai, Yuhang, Long, Xiangxing, Zhou, Dandan, Zhou, Chen, Rittmann, Bruce E
Format: Article
Language:English
Subjects:
Catalysis
Catalysts
Catalytic activity
Chlorophenol
Chlorophenols - chemistry
Cyclohexanone
Detoxification
Hydrodechlorination
Hydrogenation
Membranes
Metal Nanoparticles
Nanoparticles
Palladium
Palladium - chemistry
Phenol - chemistry
Phenols
Resource recovery
Selectivity
Treatment and Resource Recovery
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Summary:Reductive catalysis by zero-valent palladium nanoparticles (Pd0NPs) has emerged as an efficient strategy for promoting the detoxification of chlorophenols (CPs) via hydrogenation. Most studies achieved hydrodechlorination of CP to phenol for detoxification, but it requires considerably high energy input and harsh conditions to further hydrosaturate phenol to cyclohexanone (CHN) as the most desired product for resource recovery. This study documented 4-CP hydrodechlorination and hydrosaturation catalyzed by Pd0NPs deposited on H2-transfer membranes in the H2-based membrane catalyst-film reactor, which yielded up to 99% CHN selectivity under ambient conditions. It was further discovered that the Pd0 morphology and size, both determined by Pd0 loading, were the key factors controlling the catalytic activity and selectivity: while sub-nano Pd particles catalyzed only 4-CP hydrodechlorination, Pd0NPs were able to catalyze the subsequent hydrosaturation that requires more Pd0 reactive sites than hydrodechlorination. In addition, better dispersion of Pd0, caused by lower Pd0 loading, yielded higher activity for hydrodechlorination but lower activity for hydrosaturation. During the 15 day continuous tests, the substantial product from 4-CP hydrogenation was constantly phenol (>98%) for 0.2 g-Pd/m2 and CHN (>92%) for 1.0 g-Pd/m2. This study opens the door for selectively manipulating desired products from Pd0-catalyzed CP hydrogenation under ambient conditions.
ISSN:0013-936X
1520-5851
DOI:10.1021/acs.est.1c08347