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Title: Hydrodechlorination of dichlorobiphenyls over Ni-Mo/Al2O3 catalysts prepared by spray-drying method
Authors: GRYGLEWICZ, Grazyna
Stolarski, M
Gryglewicz, S
Klijanienko, A
Piechocki, W
Hoste, S
CARLEER, Robert 
Issue Date: 2006
Source: CHEMOSPHERE, 62(1). p. 135-141
Abstract: The hydrodechlorination (HDCl) process of 2,3-, 2,4- and 2,5-dichlorobiphenyls was studied over a sulphided Ni-Mo/Al2O3 catalyst in a stirred autoclave at a hydrogen pressure of 3 MPa. The catalysts were prepared by spray-drying. They were characterized by N-2 adsorption, thermogravimetry and scanning electron microscopy with X-ray microanalysis. The reaction temperature of the catalytic HDCl process was varied in the range of 230-290 degrees C. Polychlorinated biphenyls (PCBs) free transformer oil was used as reaction medium. The HDCl degree of dichlorobiphenyl isomers was in the range of 82-93%. The efficiency in the chlorine removal was found to be related to the position of the substituted chlorine atom and decreased as follows 2,4-dichlorobiphenyl approximate to 2,5-dichlorobiphenyl > 2,3-dichlorobiphenyl. For comparison, the HDCl process of 2,3-dichlorobiphenyl (2,3-PCB) without catalyst was also studied. The chlorine removal was 85% for the catalytic HDCl of 2,3-PCB whereas non-catalytic process led only to 16% of dechlorination in the same operating conditions, i.e. at 290 degrees C after 120 min. Monodichlorobiphenyls were not detected in the reaction products. The data for both catalytic and non-catalytic conversion of 2,3-PCB fit to a first-order model. Kinetic constants and the activation energy of the overall HDCl reaction of 2,3-PCB to biphenyl were evaluated. Compared to non-catalytic process, a nearly threefold decrease in the activation energy was observed in the presence of Ni-Mo/Al2O3 catalyst prepared by spray-drying (48 kJ mol(-1) vs. 124 kJ mol(-1)). (c) 2005 Elsevier Ltd. All rights reserved.
Notes: Wroclaw Univ Technol, Dept Chem, Inst Chem & Technol Petr & Coal, PL-50344 Wroclaw, Poland. State Univ Ghent, Dept Inorgan & Phys Chem, Lab Solid State Chem & Ceram Superconductors, B-9000 Ghent, Belgium. Limburgs Univ Ctr, CMK, B-3590 Diepenbeek, Belgium.Gryglewicz, G, Wroclaw Univ Technol, Dept Chem, Inst Chem & Technol Petr & Coal, Ul Gdanska 7-9, PL-50344 Wroclaw,
Keywords: hydrodechlorination; dichlorobiphenyls; Ni-Mo catalyst; kinetics
Document URI:
ISSN: 0045-6535
e-ISSN: 1879-1298
DOI: 10.1016/j.chemosphere.2005.03.097
ISI #: 000234279300017
Category: A1
Type: Journal Contribution
Validations: ecoom 2007
Appears in Collections:Research publications

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