Gas phase hydrodechlorination of chlorinated aromatic compounds on nickel catalysts

Complete hydrodechlorination of chlorobenzene and its derivatives over supported nickel catalysts under liquid phase conditions

“…In the gas phase reaction of substituted chlorobenzenes over a supported Ni/g-Al 2 O 3 catalyst [17], Suzdorf et al [19] observed a correlation between reaction rates and the donor-properties of the substituents. Konuma and Kameda [11] hydrogenolyzed chlorobenzenes para-substituted such groups as amino, methoxy, methyl, chloro, acetoxy and nitrile over Pd/AC catalyst in liquid phase, and found that the reactivities are accelerated by the presence of both electron-donating groups and electronwithdrawing groups.…”

“…Chlorobenzene and its derivatives were hydrodechlorinated on Pd/C catalyst in a flow system [10], and Pd/AlPO 4 -SiO 2 [3] and Pd/C catalysts [11] in liquid phase, but few of these catalysts are introduced to large-scale applications because of high cost of these catalysts [12,13]. Transition metal catalysts, such as Ni, NiMo on g-alumina, silica or carbon composite [14][15][16][17][18][19][20][21] required high temperature (>473 K) or high hydrogen pressure (2 MPa) [14,15] to reach significant activity in the gas phase dechlorination process. For example, parasubstituted chlorobenzenes with amino-, hydroxyl-, chloro-, methyl-and trifluoromethyl were dechlorinated over Ni/g-Al 2 O 3 [19] in the gas phase at 523 K. Little literature is reported for liquid phase hydrodechlorination of chlorinated aromatics on Ni based catalysts so far, unless Pd is added into Ni catalysts [22,23].…”

Gas phase catalytic hydroprocessing of trichlorophenols

“…Dechlorination of mono-chlorinated phenols (CPs) has been reported in the liquid phase over Pd/C 11 and in the gas phase over Ni±Mo/Al 2 O 3 12,13 and Ni/Al 2 O 3 . 14 The study by Hoke et al 11 also included dechlorination rates for di-and tri-chlorophenols (DCPs and TCPs) while Suzdorf et al 15 have concluded that the gas phase hydrogen treatment of dichlorophenol over Pd/Al 2 O 3 proceeds stepwise with cyclohexanol as the ultimate product. It is fair to state that there is still a dearth of kinetic data for catalytic hydrodechlorination of aromatic systems and the authors could ®nd no published data for the conversion of trichlorophenols in the gas phase.…”

Liquid-phase hydrodechlorination of chlorinated benzenes over active carbon supported nickel catalysts under mild conditions

“…Transition metal catalysts, such as Ni, Ni-Mo on calumina, silica or carbon composite [12][13][14][15][16][17][18][19] required high temperature (>473 K) or high hydrogen pressure (20 bar) [12,13] to reach significant activity in the gas phase dechlorination process. Little literature is reported for liquid phase HDC of chlorinated aromatics on Ni based catalysts under mild conditions so far, unless Pd is added into Ni catalysts [20,21].…”