Carbon–Chlorine and Carbon–Bromine Bond Cleavage in the Catalytic Hydrodehalogenation of Halogenated Aromatics

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

“…On the other hand, other ortho-chlorobenzenes bearing an electron-donating group were similarly active or less active than meta-and para-counterparts. Similar activity trends have been observed on Ni/SiO 2 catalyst in gas phase hydrodechlorination of chlorotoluenes [32] and chlorobromobenzenes [17]. Chlorobenzene bearing higher electron-withdrawing group, NO 2 , as compared with CF 3 or Cl group, did not hydrodechlorinate but hydrogenate at NO 2 position, and produced chloroaniline.…”

“…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].…”

Alumina‐Supported Ni–Au: Surface Synergistic Effects in Catalytic Hydrodechlorination

“…In previous studies, we have examined the action of supported Ni [1][2][3][4][5][6][7] and Pd [7][8][9][10][11][12] in promoting gas- [1][2][3][4][5][6][7][8] and liquid-phase [9][10][11][12] hydrodehalogenation reactions. This work has been directed at a low-energy detoxification/recycling of haloarenes.…”

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].…”