Pd/C Catalyzed selective hydrogenation of nitrobenzene to cyclohexanone oxime in the presence of NH2OH·HCl: Influence of the operative variables and insights on the reaction mechanism

Pietrobon, Luca; Ronchin, Lucio; Sadraoui, C.; Pontello, R.; Tosetto, C.; Vavasori, Andrea

doi:10.1016/j.apcata.2020.117570

Cited by 11 publications

(21 citation statements)

References 36 publications

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“…37 They proposed that CHOX was derived from the hydrolysis of ANIL to CHO and ANL, with the reaction between CHO and hydroxylamine hydrochloride producing CHOX. CHOX formation from the liquid-phase reaction between CHO and hydroxylamine is reported throughout the literature, 37,39,40 with hydroxylamine consistently added as a reagent. For this investigation hydroxylamine is absent from the feedstock; thus, this route is not applicable to the work presented here.…”

Section: Discussionmentioning

confidence: 98%

Mechanistic Insight Into the Application of Alumina-Supported Pd Catalysts for the Hydrogenation of Nitrobenzene to Aniline

Morisse

McCullagh

Campbell

et al. 2022

Ind. Eng. Chem. Res.

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Two Pd/γ-Al2O3 catalysts are examined for the vapor phase hydrogenation of nitrobenzene over the temperature range of 60–200 °C. A 1 wt % catalyst is selected as a reference material that is diluted with γ-alumina to produce a 0.3 wt % sample, which is representative of a metal loading linked to a candidate industrial specification aniline synthesis catalyst. Cyclohexanone oxime is identified as a by-product that is associated with reagent transformation. Temperature-programed infrared spectroscopy and temperature-programed desorption measurements of chemisorbed CO provide information on the morphology of the crystallites of the higher Pd loading catalyst. The lower Pd loading sample exhibits a higher aniline selectivity by virtue of minimization of product overhydrogenation. Reaction testing measurements that were undertaken employing elevated hydrogen flow rates lead to the proposition of separate reagent and product-derived by-product formation pathways, each of which occurs in a consecutive manner. A global reaction scheme is proposed that defines the by-product distribution accessible by the grades of catalyst examined. This information is helpful in defining product purification procedures that would be required in certain heat recovery scenarios connected with large-scale aniline production.

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Section: Discussionmentioning

confidence: 98%

Mechanistic Insight Into the Application of Alumina-Supported Pd Catalysts for the Hydrogenation of Nitrobenzene to Aniline

Morisse

McCullagh

Campbell

et al. 2022

Ind. Eng. Chem. Res.

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“…The gas-phase selective hydrogenation of 1,2-dichloro-4-nitrobenzene (DCNB) to 3,4-dichloroaniline (DCAni) was selected as a model reaction to assess the benefit of the carbon protective layer. We noted that although many different solid catalysts have been reported for the selective hydrogenation of different functionalized nitrobenzenes in the literature [1,2,5,11], there are no widely recognized benchmark systems. In particular, studies on the continuous-flow hydrogenation of DCNB were scarce, though there exists a very recent paper by Duan and co-workers [33].…”

Section: Catalytic Performance In 12-dichloro-4-nitrobenzene Hydrogen...mentioning

confidence: 99%

“…For this reason, the development of replacing heterogeneous catalysts is necessary to overcome this drawback. In this context, different catalytic systems have been reported, including precious metals (Pt [5][6][7][8][9][10], Pd [11][12][13], Ru [14,15], Ir [16], Au [17]), nonprecious metals (Co [18][19][20], Ni [21,22], Fe [22][23][24]), and metal-free catalysts [25,26]. Among these, Pt-based precious metal catalysts have been widely studied, mainly owing to their superb hydrogenating ability and extremely high chemoselectivity, the latter representing one of the main challenges in this field [1].…”

Section: Introductionmentioning

confidence: 99%

Pre-Coking Strategy Strengthening Stability Performance of Supported Nickel Catalysts in Chloronitrobenzene Hydrogenation

Wang

Lin

et al. 2021

Catalysts

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Supported nickel catalysts represent a class of important catalytic materials in selective hydrogenations, but applications are frequently limited by metal agglomeration or active-site blocking induced by the presence of hydrogen halides. Herein, we report a novel pre-coking strategy, exposing the nickel nanoparticles under methane dry reforming conditions to manipulate performance in the continuous-flow hydrogenation of 1,2-dichloro-4-nitrobenzene. Compared with the pristine nickel catalyst, the nanotube-like coke-modified nickel catalyst showed weakened hydrogenating ability, but much improved stability and slightly better selectivity to the target product, 3,4-dichloroaniline. Characterization results revealed that the strengthened stability performance can be mainly linked to the reduced propensity to retain chlorine species, which seems to block the access of the substrate molecules to the active sites, and thus is a major cause of catalyst deactivation on the pristine nickel catalyst. Coke deposition can occur on the pre-coked nickel catalyst but not on the pristine analog; however, the impact on the stability performance is much milder compared with that on chlorine uptake. In addition, the presence of coke is also beneficial in restraining the growth of the nickel nanoparticles. Generally, the developed method might provide an alternative perspective on the design of novel transition-metal-based catalytic materials for other hydrogenation applications under harsh conditions.

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“…Starting from these considerations, it is clear that the main concern of the whole one-pot process is strictly related to the hydroxylamine in the reaction environment, in fact, hydroxylammonium salt are sparingly soluble. For this reason the oximation process are slow, thus needs quite high temperature in order to achieve partial dissolution, for increasing formation of free oxime, and finally to speed up reaction rate [25]. Furthermore, it is necessary to take into account that the use of liquid hydroxylamine is not industrially desirable due to the intrinsic instability of the compound, which may cause devastating explosion in plants as already occurred in the CSI plant of Allentown Pennsylvania on February 1999 [26].…”

Section: Introductionmentioning

confidence: 99%

Trifluoroacetic Acid Hydroxylamine System as Organocatalyst Reagent in a One-Pot Salt Free Process for the Synthesis of Caprolactam and Amides of Industrial Interest

et al. 2021

Self Cite

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In this work we studied the reactivity of the Trifluoroacetic acid hydroxylamine system in the one step salt free synthesis of amides from ketones. A particular regards was paid to the caprolactam synthesis because of its industrial relevance. Synthesis, reactivity and characterization of the hydroxylamine trifluoroacetate is given. Fast oximation reaction of several ketones was gained at room temperature (1 h of reaction quantitative conversion for several ketones). In the same reactor, by raising the temperature at 383 K, the Beckmann rearrangement of the so obtained oximes is easily accomplished in the presence of three equivalent of TFA. The possibility of obtaining the trifluoroacetate of the hydroxylamine with a modified nitric acid hydrogenation reactions was verified, too. Reuse of solvent and trifluoroacetic acid is easily achieved by distillation. Graphical abstract Salt free one-pot caprolactam and amides process catalyzed by CF3COOH, in the presence of NH2OH TFA as the oximation agent.

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Pd/C Catalyzed selective hydrogenation of nitrobenzene to cyclohexanone oxime in the presence of NH2OH·HCl: Influence of the operative variables and insights on the reaction mechanism

Cited by 11 publications

References 36 publications

Mechanistic Insight Into the Application of Alumina-Supported Pd Catalysts for the Hydrogenation of Nitrobenzene to Aniline

Mechanistic Insight Into the Application of Alumina-Supported Pd Catalysts for the Hydrogenation of Nitrobenzene to Aniline

Pre-Coking Strategy Strengthening Stability Performance of Supported Nickel Catalysts in Chloronitrobenzene Hydrogenation

Trifluoroacetic Acid Hydroxylamine System as Organocatalyst Reagent in a One-Pot Salt Free Process for the Synthesis of Caprolactam and Amides of Industrial Interest

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