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Title: Characterization and reactivity of Pd supported on ZnAl2O4 catalysts for direct coupling of ethylbenzene dehydrogenation with nitrobenzene hydrogenation
Authors: Harikrishna, Yengaldas
Kumar, Vanama Pavan
Chary, Komandur V R
Rao, Vattikonda Venkat
Keywords: Catalysts;Palladium catalysts;Coupling reactions;Supported catalysts;Dehydrogenation;Hydrogenation;Spinel oxides;Zinc aluminate;Ethylbenzene;Nitrobenzene
Issue Date: Apr-2014
Publisher: NISCAIR-CSIR, India
Abstract: The ZnAl2O4 supported palladium catalysts have been described for the first time in the direct coupling of dehydrogenation of ethylbenzene with hydrogenation of nitrobenzene, in a fixed bed catalytic reactor at atmospheric pressure in the temperature range of 673−823 K. The former reaction is reversible, endothermic, thermodynamically limited and also supplies hydrogen to produce styrene. However, the latter is irreversible, exothermic and consumes in situ hydrogen to produce aniline, thereby making the coupling reaction slightly exothermic and additionally overcoming thermodynamic constraints. A series of palladium (0.25−4.0 wt%) catalysts supported on crystalline ZnAl2O4 have been prepared and their catalytic activities studied in the coupling reaction. The catalyst samples are characterized by X-ray diffraction, H2-temperature programmed reduction, CO chemisorption and BET surface area data. The metal dispersion and particle size are obtained by CO chemisorption method. The reaction profile shows that 0.5 wt% palladium is an optimum loading to obtain maximum conversions of ethylbenzene (52.3%) and nitrobenzene (43.9%) to give 88.3% and 100% selectivity of styrene and aniline products respectively.
Page(s): 459-466
ISSN: 0975-0975(Online); 0376-4710(Print)
Appears in Collections:IJC-A Vol.53A(04-05) [April-May 2014]

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