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Taghavi F.,Azerbaijan State Oil Academy | Taghavi F.,Chlor Pars Co. | Falamaki C.,Amirkabir University of Technology | Shabanov A.,Azerbaijan State Oil Academy | And 2 more authors.
Reaction Kinetics, Mechanisms and Catalysis | Year: 2013

The morphology of supported nickel boride nanoparticles depends strongly on the exposed surface cation exchange property of the support. Despite having a substantially higher loading of nickel boride, the α-Al2O 3 supported catalyst exhibits a significantly lower catalytic activity for the hydrogenation of p-nitrophenol. Use of a supporting material like clinoptilolite allows the re-use of the catalyst up to three times. However, the catalytic activity decreases after each hydrogenation process. Unsupported nickel boride and α-Al2O3 supported nickel boride result in unwanted trace impurities in the final p-aminophenol crystalline product. Such impurities are absent using clinoptilolite and kieselguhr supports. © 2013 Akadémiai Kiadó, Budapest, Hungary. Source


Taghavi F.,Azerbaijan State Oil Academy | Taghavi F.,Chlor Pars Co. | Falamaki C.,Amirkabir University of Technology | Shabanov A.,Azerbaijan State Oil Academy | And 2 more authors.
Applied Catalysis A: General | Year: 2011

The present work concerns a thorough investigation of the performance of a nano-nickel boride catalyst for the direct hydrogenation of p-nitrophenol (PNP) to p-aminophenol (PAP) in a batch slurry reactor using ethanol as solvent. The effect of pH during the synthesis procedure on the properties of the as-synthesized catalyst has been investigated using FTIR, XRD, ICP and FESEM analysis. The synthesized catalyst shows a better activity with respect to Raney nickel. The effect of catalyst preparatory method on its activity has been investigated. The effect of reaction temperature (40-80 °C), PNP initial concentration (0.07-0.28 g mL-1) and initial pressure (25-40 bar) on the reaction kinetics has been investigated. It has been shown that the kinetic behavior throughout the whole time domain could be reasonably predicted considering a single site mechanism with atomically adsorbed hydrogen and PNP adsorption as the controlling step. © 2011 Elsevier B.V. All rights reserved. Source


Taghavi F.,Azerbaijan State Oil Academy | Taghavi F.,Chlor Pars Co. | Falamaki C.,Amirkabir University of Technology | Shabanov A.,Azerbaijan State Oil Academy | And 2 more authors.
Applied Catalysis A: General | Year: 2013

It is shown that low temperature (<100 °C) hydrogen treatment of nano nickel boride catalysts is an efficient process for the enhancement of their activity in the p-nitrophenol (PNP) to p-aminophenol (PAP) hydrogenation reaction. It has been shown that such a process excludes initial borate species present on the surface and within the catalyst nano-particles by promoting their dissolution in the liquid phase. The latter phenomenon is enhanced by increasing the temperature. Treatment in the absence of hydrogen results in no reaction rate enhancement. Instead, the activity falls significantly below that of the as-synthesized catalyst. The effect of hydrogen treatment on the catalyst physical properties was investigated using FTIR, XRD, nitrogen adsorption and FESEM analysis. Mathematical simulation of the PNP hydrogenation reaction rate supports the hypothesis that the rate enhancement is mainly due to the increase of the catalyst specific surface area and partial reduction of surface nickel oxide species. The mechanism by which hydrogen increases the specific surface is discussed. © 2013 Elsevier B.V. Source

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