Hydrodechlorination of polychlorinated molecules using transition metal phosphide catalysts.
Ni2P and CoP catalysts (5 wt.% of metal) supported on a commercial SiO2 were tested in the gas phase catalytic hydrodechlorination (HDCl) of mono (chlorobenzene-ClB) and polychlorobenzenes (PCBs) (1,2- dichlorobenzene (1,2-DClB), 1,3-dichlorobenzene (1,3-DClB), 1,4-dichlorobenzene (1,4-DClB), and 1,2,4-trichlorobenzene (1,2,4-TClB)) at atmospheric pressure. It was investigated how the number and position of chlorine atoms in the molecule influence the HDCl activity. The prepared catalysts were characterized by X-ray diffraction (XRD), CO chemisorption, N2 adsorption-desorption at -196°C, and X-ray photoelectron spectroscopy (XPS). Characterization results indicated better active phase dispersion and greater amount of P on the Ni2P catalyst surface. Catalytic results showed that the Ni2P was more active and stable in this type of reactions. The hydrodechlorination activity decreased by increasing the number of chlorine atoms in the molecule and chlorine substituents in close proximity. The observed trend in the HDCl activity was: ClB>1,4-DClB>1,3-DClB>1,2-DClB>1,2,4-TClB. The exception was the catalytic response after 24h on stream observed for the Ni2P in the HDCl reaction of 1,2,4-TClB, which was equal to that observed for the 1,4-DClB molecule, and also yielding benzene as the main reaction product.
Departamento de Química Inorgánica, Cristalografía y Mineralogía, Facultad de Ciencias, Universidad de Málaga, Campus de Teatinos, 29071 Málaga, Spain.
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Cecilia
Departamento de Química Inorgánica, Cristalografía y Mineralogía, Facultad de Ciencias, Universidad de Málaga, Campus de Teatinos, 29071 Málaga, Spain. Electronic address: ainfantes@uma.es.
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Infantes-Molina
Departamento de Química Inorgánica, Cristalografía y Mineralogía, Facultad de Ciencias, Universidad de Málaga, Campus de Teatinos, 29071 Málaga, Spain.
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Rodríguez-Castellón
D002384:Catalysis; D002722:Chlorobenzenes / Q000737:chemistry*; D003035:Cobalt / Q000737:chemistry*; D004785:Environmental Pollutants / Q000737:chemistry*; D054879:Halogenation; D009532:Nickel / Q000737:chemistry*; D044367:Phase Transition; D017553:Phosphorus Compounds / Q000737:chemistry*; D012037:Refuse Disposal; D012822:Silicon Dioxide / Q000737:chemistry; D013329:Structure-Activity Relationship; D014961:X-Ray Diffraction
D002722:Chlorobenzenes; D004785:Environmental Pollutants; D017553:Phosphorus Compounds; D003035:Cobalt; D012822:Silicon Dioxide; D009532:Nickel
CoP; Hydrodechlorination; Ni(2)P; Polychlorobenzenes; Silica; Transition metal phosphides