TY - JOUR
T1 - Clean production of chloroanilines by selective gas phase hydrogenation over supported Ni catalysts
AU - Cardenas-Lizana, Fernando
AU - Gómez-Quero, Santiago
AU - Keane, Mark A.
PY - 2008/1/1
Y1 - 2008/1/1
N2 - We have established for the first time 100% selectivity in the continuous gas phase hydrogenation of p-chloronitrobenzene (p-CNB) to p-chloroaniline for reaction over a series of oxide and carbon supported Ni catalysts (6 ± 2%, w/w) under mild reaction conditions (T = 393 K, P = 1 atm). Catalyst activation by temperature programmed reduction (TPR) is addressed, BET area and H2 uptake measurements provided and mean metal particle sizes evaluated by transmission electron micrographic (TEM) analysis. The following activity sequence has been determined: Ni/Al2O3 > Ni/SiO2 > Ni/Activated Carbon > Ni/graphite. Pd/Al2O3, as an alternative catalyst, delivered an appreciably higher activity but with the production of nitrobenzene (principal product) and aniline (secondary product), i.e. hydrodechlorination with subsequent -NO2 reduction prevailed. Exclusive formation of the corresponding haloaniline is also demonstrated for the hydrogenation of o-chloronitrobenzene, m-chloronitrobenzene and p-bromonitrobenzene over Ni/Al2O3. A lower hydrogenation rate is established for p-CNB relative to nitrobenzene, consistent with a halogen substituent deactivation effect. While the Ni catalysts suffered a loss of activity with time-on-stream, exclusive selectivity to the haloamine product was maintained. These preliminary results can serve as a basis for the development of a cleaner, high throughput production of commercially important haloamines. © 2007 Elsevier B.V. All rights reserved.
AB - We have established for the first time 100% selectivity in the continuous gas phase hydrogenation of p-chloronitrobenzene (p-CNB) to p-chloroaniline for reaction over a series of oxide and carbon supported Ni catalysts (6 ± 2%, w/w) under mild reaction conditions (T = 393 K, P = 1 atm). Catalyst activation by temperature programmed reduction (TPR) is addressed, BET area and H2 uptake measurements provided and mean metal particle sizes evaluated by transmission electron micrographic (TEM) analysis. The following activity sequence has been determined: Ni/Al2O3 > Ni/SiO2 > Ni/Activated Carbon > Ni/graphite. Pd/Al2O3, as an alternative catalyst, delivered an appreciably higher activity but with the production of nitrobenzene (principal product) and aniline (secondary product), i.e. hydrodechlorination with subsequent -NO2 reduction prevailed. Exclusive formation of the corresponding haloaniline is also demonstrated for the hydrogenation of o-chloronitrobenzene, m-chloronitrobenzene and p-bromonitrobenzene over Ni/Al2O3. A lower hydrogenation rate is established for p-CNB relative to nitrobenzene, consistent with a halogen substituent deactivation effect. While the Ni catalysts suffered a loss of activity with time-on-stream, exclusive selectivity to the haloamine product was maintained. These preliminary results can serve as a basis for the development of a cleaner, high throughput production of commercially important haloamines. © 2007 Elsevier B.V. All rights reserved.
KW - Carbon and oxide supported Ni
KW - p-Chloroaniline
KW - p-Chloronitrobenzene
KW - Selective hydrogenation
UR - http://www.scopus.com/inward/record.url?scp=37249026646&partnerID=8YFLogxK
U2 - 10.1016/j.apcata.2007.10.007
DO - 10.1016/j.apcata.2007.10.007
M3 - Article
SN - 0926-860X
VL - 334
SP - 199
EP - 206
JO - Applied Catalysis A: General
JF - Applied Catalysis A: General
IS - 1-2
ER -