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Studer, Martin; Neto, Sidney Aquino; Blaser, Hans‐Ulrich

doi:10.1023/a:1009050804228

Cited by 43 publications

(25 citation statements)

References 5 publications

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“…It was reported that the addition of catalytic amounts of vanadium promoters could reduce the accumulation of PHA during the hydrogenation of aromatic nitro compounds over Pd or Pt catalysts [11]. For Ni catalysts used for the hydrogenation in organic solvents, however, the selection of effective promoters is difficult because modifiers that reduce the accumulation usually lower the reaction rate [34]. In this context, the present results of hydrogenation in scCO 2 over Ni/Al 2 O 3 ( Fig.…”

Section: Properties Of Ni Catalystsmentioning

confidence: 67%

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Selective hydrogenation of nitrobenzene to aniline in dense phase carbon dioxide over Ni/γ-Al2O3: Significance of molecular interactions

Meng

Cheng

Akiyama

et al. 2009

Journal of Catalysis

142

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The selective hydrogenation of nitrobenzene (NB) over Ni/γ-Al 2 O 3 catalysts was investigated using different media of dense phase CO 2 , ethanol, and n-hexane. In dense phase CO 2 , the total rate of NB hydrogenation was larger than that in organic solvents under similar reaction conditions; the selectivity to the desired product, aniline, was almost 100% over the whole conversion range of 0-100%. The phase behavior of the reactant mixture in/under dense phase CO 2 was examined at reaction conditions. In situ high-pressure Fourier transform infrared measurements were made to study the molecular interactions of CO 2 with the following reactant and reaction intermediates: NB, nitrosobenzene (NSB), and N-phenylhydroxylamine (PHA). Dense phase CO 2 strongly interacts with NB, NSB, and PHA, modifying the reactivity of each species and contributing to positive effects on the reaction rate and the selectivity to aniline. A possible reaction pathway for the hydrogenation of NB in/under dense phase CO 2 over Ni/γ-Al 2 O 3 is also proposed.

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Section: Properties Of Ni Catalystsmentioning

confidence: 67%

“…The path IV in Scheme 1 occurs on Au/TiO 2 , and the step V becomes significant over Pd/Pt/Ni catalysts in the presence of vanadium promoters [9,11,34]. Herein, we discuss the different reaction pathways in dense phase CO 2 and in ethanol without the consideration of pathways IV and V.…”

Section: Reaction Pathway For the Hydrogenation Of Nb In Dense Phase mentioning

confidence: 99%

Selective hydrogenation of nitrobenzene to aniline in dense phase carbon dioxide over Ni/γ-Al2O3: Significance of molecular interactions

Meng

Cheng

Akiyama

et al. 2009

Journal of Catalysis

142

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“…The suppression of formation of hydroxylamine is a topic of industrial importance because aryl hydroxylamines are generally accumulated in large amounts during the hydrogenation of nitroaromatics with electron-withdrawing substituents (e.g., halogen or sulfonamide) [3,7]. Studer et al found that the accumulation of hydroxylamine in methanol at 30-35°C could be reduced from 70-80% over unmodified Raney Ni to 11% by careful selection of vanadium promoters; simultaneously, the reaction rate was down by a factor of 0.1 [7].…”

Section: Features Of Ni Catalysts For Selective Hydrogenation Of Cnbmentioning

confidence: 99%

“…Studer et al found that the accumulation of hydroxylamine in methanol at 30-35°C could be reduced from 70-80% over unmodified Raney Ni to 11% by careful selection of vanadium promoters; simultaneously, the reaction rate was down by a factor of 0.1 [7]. Mahata [37].…”

Section: Features Of Ni Catalysts For Selective Hydrogenation Of Cnbmentioning

confidence: 99%

“…The path IV in Scheme 1 occurs on Au/TiO 2 , and the step V becomes significant over Pd/Pt/Ni catalysts in the presence of vanadium promoters [2,3,7]. Herein, we discuss the reaction pathways over Ni/TiO 2 in dense phase CO 2 without the consideration of pathways IV and V. The total yield of all byproducts was <3.5% over the whole conversion range of 9-100% ( Fig.…”

Section: Reaction Pathways For the Hydrogenation Of Cnb In Scco 2 Ovementioning

confidence: 99%

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Selective hydrogenation of chloronitrobenzene to chloroaniline in supercritical carbon dioxide over Ni/TiO2: Significance of molecular interactions

Meng

Cheng

Fujita

et al. 2010

Journal of Catalysis

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The hydrogenation of chloronitrobenzene to chloroaniline was investigated over Ni/TiO 2 at 35°C in supercritical CO 2 (scCO 2 ), ethanol, and n-hexane. The reaction rate followed the order of scCO 2 > n-hexane > ethanol. In scCO 2 , the selectivity to chloroaniline and to aniline over Ni/TiO 2 were 97-99.5% and <1%, respectively, in the conversion range of 9-100%. The high chemoselectivity to chloroaniline cannot be achieved over Ni/TiO 2 in ethanol and n-hexane. In situ high-pressure Fourier transform infrared measurements were made to study the molecular interactions of CO 2 with the following reactant and reaction intermediates: chloronitrobenzene, chloronitrosobenzene, and N-chlorophenylhydroxylamine. The molecular interaction modifies the reactivity of each species and accordingly the reaction rate and the selectivity. The influence of Cl substituent on the interaction modes of CO 2 with these reacting species is discussed. Possible reaction pathways for the hydrogenation of chloronitrobenzene in scCO 2 over Ni/TiO 2 are also proposed.

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