Active Pd/Fe(OH)  catalyst preparation for nitrobenzene hydrogenation by tracing aqueous phase chlorine concentrations in the washing step of catalyst precursors

Zhang, Chengming; Cui, Xinjiang; Deng, Yuanfu; Shi, Feng

doi:10.1016/j.tet.2014.02.057

Cited by 8 publications

(5 citation statements)

References 29 publications

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“…In order to stimulate the maximum catalytic potential of the catalyst, the following methods are usually adopted: (1) preparation of catalysts with specific morphology for increasing the specific surface area and exposing more active sites of the catalysts; (2) loading the catalysts on the support to improve its stability, avoid the agglomeration, and extend the service life of the catalysts; − and (3) adding the transition metal M (Ni, Co, Fe, Cu, Ag, etc.) to form the bimetal or multiple metal catalysts with Pd, thus reducing the consumption of noble metals, and some synergies will be achieved among the different metals that will substantially benefit the efficiency of the noble catalyst. − At present, most of the catalysts used for hydrogenation of NB to AN are supported catalysts, and the impregnation and precipitation are the commonly used methods. Mark et al used Al 2 O 3 as a carrier to synthesize supported mono-(Pd or Ni) and bimetallic (Pd/Ni = 1:3, 1:1, and 3:1) catalysts by an equal volume impregnation method.…”

Section: Introductionmentioning

confidence: 99%

Three-Dimensional Network Pd-Ni/γ-Al₂O₃ Catalysts for Highly Active Catalytic Hydrogenation of Nitrobenzene to Aniline under Mild Conditions

Yang

et al. 2021

ACS Omega

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In view of the current situation of high cost and low catalytic efficiency of the commercial Pd-based catalysts, adding transition metals (Ni, Co, etc.) to form the Pd-M bimetallic catalyst not only reduces the consumption of Pd but also greatly improves the catalytic activity and stability, which has attracted increasing attention. In this work, the three-dimensional network Pd–Ni bimetallic catalysts were prepared successfully by a liquid-phase in situ reduction method with the hydroxylated γ-Al 2 O 3 as the support. Through investigating the effects of the precursor salt amount, reducing agent concentration, stabilizer concentration, and reducing stirring time on the synthesis of the Pd–Ni nanocatalyst, the three-dimensional network Pd–Ni bimetallic nanostructures with four different atomic ratios were prepared under an optimal condition. The obtained wire-like Pd–Ni catalysts have a uniform diameter size of about 5 nm and length up to several microns. After closely combining with the hydroxylated γ-Al 2 O 3 , the supported Pd–Ni/γ-Al 2 O 3 catalysts exhibit nearly 100% conversion rate and selectivity for the hydrogenation of nitrobenzene to aniline at low temperature and normal pressure. The stability testing of the supported Pd–Ni/γ-Al 2 O 3 catalysts shows that the conversion rate still remained above 99% after 10 cycles. There is no doubt that the supported catalysts show significant catalytic efficiency and recyclability, which provides important theoretical basis and technical support for the preparation of low-cost, highly efficient catalysts for the hydrogenation of nitrobenzene to aniline.

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Section: Introductionmentioning

confidence: 99%

Three-Dimensional Network Pd-Ni/γ-Al₂O₃ Catalysts for Highly Active Catalytic Hydrogenation of Nitrobenzene to Aniline under Mild Conditions

Yang

et al. 2021

ACS Omega

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“…However, reduced selectivity, over-reduction, and various side reactions were constantly observed with these highly active catalysts when reducible, labile, and strong leaving groups are typically involved in the nitroaromatics molecules. Therefore, Cu-, Ag-, and Au-based transition-metal catalysts were advanced for the selective transformation of nitroaromatics into aromatic amine at the expense of low hydrogenation activity and harsh reaction conditions. , In addition to metal catalysis, carbonaceous material-promoted metal-free reduction of nitroaromatics is of great interest in academic research.…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, Cu-, 9 Ag-, 10 and Au- 11 based transition-metal catalysts were advanced for the selective transformation of nitroaromatics into aromatic amine at the expense of low hydrogenation activity and harsh reaction conditions. 12,13 In addition to metal catalysis, carbonaceous material-promoted metal-free reduction of nitroaromatics is of great interest in academic research.…”

Section: Introductionmentioning

confidence: 99%

Metal-Free H₂ Activation for Highly Selective Hydrogenation of Nitroaromatics Using Phosphorus-Doped Carbon Nanotubes

Chen

Shen

et al. 2019

ACS Appl. Mater. Interfaces

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We reported that phosphorus-doped carbon nanotubes (P-CNTs), showing metal-like properties, can efficiently promote metal-free hydrogenation of nitrobenzene (1a) to aniline (2a) using molecular hydrogen (H2) as a reducing reagent under very mild conditions with a reaction temperature of only 50 °C. The kinetics of 1a hydrogenation over P-CNT reveals that the hydrogenation rate of 1a is a first-order dependence on the H2 pressure and the P-CNT loading level, and a zero-order dependence on 1a concentration, demonstrating the rate-determining step of H2 adsorption and activation over P-CNT. The activation energy of P-CNT-catalyzed 1a hydrogenation is 43 ± 3 kJ mol–1 with the turnover frequency around 3.60 ± 0.12 h–1 at 50 °C. In addition to 1a, the general applicability of the P-CNT-promoted metal-free hydrogenation process is further demonstrated by applying various functionalized nitroaromatics with wide industrial interest. The P-CNT shows both excellent yields and selectivities to hydrogenation with respect to reducible, labile, and strong leaving groups on the nitroaromatics molecules. The stability and reusability of the P-CNT demonstrate up to eight-time recycling without evident loss of activity and selectivity. In addition to hydrogenation, metal-free catalytic transfer hydrogenation of 1a is achieved with P-CNT using diverse hydrogen sources, including hydrazine hydrate (N2H4·H2O), carbon monoxide/water (CO/H2O), and formic acid/triethylamine (HCOOH/Et3N).

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“…Palladium supported on Fe(OH)x has also been used for hydrogenation of nitroaromatics under atmospheric pressure. However, at slightly higher temperatures of ∼60 °C very high catalyst loading (∼41%) with respect to the substrate has been used (TOF ∼141 h −1 ) . Palladium supported on SiO 2 core shell catalyst and ligand capped Pt nano particles supported on carbon have shown hydrogenation at atmospheric pressure but at higher temperature with almost 100% and upto 80% nitrobenzene conversion respectively ,.…”

Section: Resultsmentioning

confidence: 99%

Palladium Supported on Fluorinated Magnesium Hydroxide: An Efficient Catalyst for Hydrogenation under Ambient Conditions

et al. 2017

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In this study palladium supported on fluorinated magnesium hydroxide (Pd‐MgF2‐x(OH)x) was synthesized by fluorination of magnesium hydroxide using aqueous HF as fluorinating agent. The Mg(OH)2 dissolves in HF and precipitates as magnesium hydroxide fluoride. The Pd precursor was added in the same pot during precipitation of MgF2‐x(OH)x. The final catalyst after drying at 250 °C has shown very high efficiency for hydrogenation of styrene and range of nitro aromatics at room temperature and atmospheric pressure. Hydrogenation of styrene has led to 37% conversion with 100% selectivity for hydrogenation of double bond after 3 h. The catalyst was successfully recycled for styrene hydrogenation without appreciable loss in the activity. Further hydrogenation of nitro‐aromatics was achieved with 99% conversion and 100% aniline selectivity at room temperature and atmospheric pressure. The turnover number of ∼21774 was obtained for nitrobenzene hydrogenation. The catalyst has shown mesoporous nature (pore volume 0.25 cc/g, pore diameter 4.8 nm) with very high surface area of 106 m2/g. The palladium particle size was found to be in the range of 10–11 nm. Acidity measurements by FTIR of adsorbed pyridine revealed presence of Lewis acidic sites with moderate acidity. Mechanistic studies using in‐situ FTIR analysis for nitrobenzene hydrogenation revealed activation of nitrobenzene on the Lewis acid sites of the support whereas activation of hydrogen by heterolytic cleavage on Pd center.

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Active Pd/Fe(OH) catalyst preparation for nitrobenzene hydrogenation by tracing aqueous phase chlorine concentrations in the washing step of catalyst precursors

Cited by 8 publications

References 29 publications

Three-Dimensional Network Pd-Ni/γ-Al₂O₃ Catalysts for Highly Active Catalytic Hydrogenation of Nitrobenzene to Aniline under Mild Conditions

Three-Dimensional Network Pd-Ni/γ-Al₂O₃ Catalysts for Highly Active Catalytic Hydrogenation of Nitrobenzene to Aniline under Mild Conditions

Metal-Free H₂ Activation for Highly Selective Hydrogenation of Nitroaromatics Using Phosphorus-Doped Carbon Nanotubes

Palladium Supported on Fluorinated Magnesium Hydroxide: An Efficient Catalyst for Hydrogenation under Ambient Conditions

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Active Pd/Fe(OH) catalyst preparation for nitrobenzene hydrogenation by tracing aqueous phase chlorine concentrations in the washing step of catalyst precursors

Cited by 8 publications

References 29 publications

Three-Dimensional Network Pd-Ni/γ-Al2O3 Catalysts for Highly Active Catalytic Hydrogenation of Nitrobenzene to Aniline under Mild Conditions

Three-Dimensional Network Pd-Ni/γ-Al2O3 Catalysts for Highly Active Catalytic Hydrogenation of Nitrobenzene to Aniline under Mild Conditions

Metal-Free H2 Activation for Highly Selective Hydrogenation of Nitroaromatics Using Phosphorus-Doped Carbon Nanotubes

Palladium Supported on Fluorinated Magnesium Hydroxide: An Efficient Catalyst for Hydrogenation under Ambient Conditions

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Three-Dimensional Network Pd-Ni/γ-Al₂O₃ Catalysts for Highly Active Catalytic Hydrogenation of Nitrobenzene to Aniline under Mild Conditions

Three-Dimensional Network Pd-Ni/γ-Al₂O₃ Catalysts for Highly Active Catalytic Hydrogenation of Nitrobenzene to Aniline under Mild Conditions

Metal-Free H₂ Activation for Highly Selective Hydrogenation of Nitroaromatics Using Phosphorus-Doped Carbon Nanotubes