Chlorobenzene hydrodechlorination

Scheme 4.30 Hydrodechlorination of chlorobenzene using active flow cells in a continuous-flow microwave process.

In order to determine the reaction pathway for 1,2-dichlorobenzene, Schiith fitted kinetic data and found that the primary pathway was direct reaction to benzene with a parallel reaction of sequential dechlorination through chlorobenzene to benzene. (Figure 7) These pathways were further supported by independent determination and verification of the reaction rate constant for the second hydrodechlorination step. (Schiith and Reinhard 1998)... 

HYDRODECHLORINATION OF CHLOROBENZENE OVER MgO MODIFIED Pt/ALOa CATALYSTS... 

AI2O3 was modified with MgO and was used as support in the preparation of platinum catalysts. The prepared catalysts were characterised by Scaning electron microscope (SEM), X-ray diffraction (XRD), chemisorption ofH2and BET surface area and were tested for their activity in hydrodechlorination of chlorobenzene. The investigations show that support modification reduces catalyst deactivation remarkably. The catalysts are also found to be active and selective for the hydrodechlorination of chlorobenne reaction. 

This study shows that modification of AI2O3 increases the deactivation resistance of Pt catalysts in hydrodechlorination of chlorobenzene. Besides a near total selectivity to cyclohexane is obtained on modified AI2O3 supported platinum catalysts. 

G Tavoularis, MA Keane. Gas phase catalytic hydrodechlorination of chlorobenzene over nickel/silica. J. Chem. Technol. Biotechnol. 74 60-70,1999. 

MA Keane, DYu Murzin. A kinetic treatment of the gas phase hydrodechlorination of chlorobenzene over nickel/silica beyond conventional kinetics. Chem. Eng. Sci. 56 3185-3195,2001. 

Microwave calcination of magnesia, alumina, and silica-supported Pd and Pd-Fe catalysts resulted in their having enhanced catalytic activity in test reactions -hydrogenation of benzene and hydrodechlorination of chlorobenzene - compared with conventionally prepared catalysts [14-16]. The greater catalytic activity was attributed to prevention of the formation of a Pd-Fe alloy of low activity, which occurs at the high reduction temperature used in conventional heating. 

Hydrodechlorination of chlorobenzene-tetrachloroethylene mixtures over a Pd/AlaOa catalyst... 

Likewise, Pd-[Rh(cod)Cl]2 (as well as some analogous catalysts combined with other metal particles and complexes suchas Rh-Pd(NOs)2, Ni-[Rh(cod)Cl]2 and Pt- [Rh(cod)-(PPh3)2][Pp6] ) were shown to promote hydrodechlorination of a variety of mono- and polychloroarenes. Of particular importance is the conversion of major polychlorinated environmental pollutants and toxins into non-aromatic halogen-free hydrocarbons. The hy-drodehalogenation of l,l -(2,2,2-trichloroethylidene)bis(4-chlorobenzene) (DDT), 2,2 -methylenebis( 3,4,6-trichlorophenol) (Hexachlorophene), 2,4,5-trichlorophenoxyacetic acid (2,4,5-T), polychlorinated biphenyl (PCB), polychlorinated dibenzo[, r]dioxinc... 

Nanocomposites based on Pd and Ni encapsulated ( ) in caibon have been prepared by condensation of nanoparticles in the flow of gas mixture (Ar and hydrocarbons) and characterized by TEM, TGA-MS, XRD spectroscopy and BET adsorption measurements. Ni C, NiPd C nanocomposites consist of metal core 3-10 nm in size covered by a few carbon layers Pd particles are 10-15 nm in size, have no caibon shell and are joined in chains. Catalytic properties were investigated in hydrodechlorination (HDC) of chlorobenzene in gas phase and 1,2,4-trichlorobenzene in liquid phase. Totally carbon covered particles of Ni and Pd-Ni demonstrate high activity and stabiUty in gas-phase hydrodechlorination of chlorobenzene at 100-350°C and in liquid phase HDC of 1,2,4-trichlorobenzene at 130°C under middle pressme. 

Catalytic hydrodechlorination (HDC) of chlorobenzene HDC of chlorobenzene (CB) proceeds according the following scheme... 

The activity of catalysts was tested in gas phase hydrodechlorination (HDC) of chlorobenzene and multiphase HDC of various chlorinated aromatic compounds chlorobenzene 1,3,5-tiichlorobenzene 2,4,8-trichlorodibenzofuran and hexachlorobenzene. 

The hydrodechlorination of chlorobenzene, and conversion 4-chlo-ro-2-nitrQ-aniline to orthophenylenediamine was carried out under different reaction conditions using stirred tank and trickle bed reactors in the pressure range of 1-70 bar. The reductive amination of acetone was studied in a continuous flow gas phase reactor at 20-50 bar and 1B0-2DQ°C. Both in the hydrodehalogenation and reductive amination the reaction products were analysed by gas chromatography. ... 

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