NbOx/SiO2 in the gas-phase Beckmann rearrangement of cyclohexanone oxime to ε-caprolactam: Influence of calcination temperature, niobia loading and silylation post-treatment

Maronna, Marius M.; Kruissink, E.C.; Parton, Rudy F.; Tinge, J.T.; Soulimani, Fouad; Weckhuysen, Bert M.; Hoelderich, Wolfgang F.

doi:10.1016/j.apcatb.2015.12.014

Cited by 12 publications

(26 citation statements)

References 43 publications

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“…The surface area of the Al 2 O 3 support reduces slightly after only Pt supported, which should be related to the pores of the Al 2 O 3 support blocked by the Pt metal or its oxides. However, the surface area of catalysts slightly increases when NbO x was added to the catalyst, which may be attributed to the porous structure of NbO x species uniformly dispersed on the Al 2 O 3 support. , …”

Section: Resultsmentioning

confidence: 99%

Understanding the Role of NbO_x on Pt/Al₂O₃ for Effective Catalytic Propane Oxidation

Zhao

Liao

et al. 2019

Ind. Eng. Chem. Res.

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Catalytic combustion is an effective way to eliminate volatile organic compound (VOC) pollution, such as propane. However, it is still a significant challenge to develop effective catalysts. Herein, we report NbO x -doped Pt/Al2O3 catalysts synthesized by a facile impregnation method for effective propane oxidation. New types of acidic sites are generated on the surface of Pt/Al2O3 when NbO x is added, and the acidity is gradually improved. NbO x is beneficial for the formation of Pt0 species, which obviously improves the catalytic performance. Pt-10Nb/Al2O3 gives the highest propane conversion (86.6%) at 250 °C. Furthermore, the prereduced Pt-10Nb/Al2O3-R with more Pt0 content shows higher conversion (90.1%). The specific reaction rate of Pt-Nb/Al2O3 is related to the Pt0/(Pt0 + Pt2+) ratio. Pt-10Nb/Al2O3-R with the Pt0/(Pt0 + Pt2+) value of 0.86 rather than Pt-15Nb/Al2O3 with a higher one gives the highest specific reaction rate of 76.1 μmol gPt –1 s–1, which may be attributed to the synergistic roles of Pt0 and Pt2+ species.

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Section: Resultsmentioning

confidence: 99%

Understanding the Role of NbO_x on Pt/Al₂O₃ for Effective Catalytic Propane Oxidation

Zhao

Liao

et al. 2019

Ind. Eng. Chem. Res.

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“…Cyclohexanone oxime is a key intermediate in the production of ε-caprolactam (a precursor of nylon-6) through the Beckmann rearrangement. 27 Conventional titanosilicate catalysts (Ti-MWW and TS-1) exhibit excellent performances in the liquid-phase ammoximation of cyclohexanone with ammonia and hydrogen peroxide to prepare cyclohexanone oxime. 28 Nevertheless, synthesis of titanosilicate is a complex and tedious procedure, and requires the use of a large amount of expensive organic structure-directing agents (e.g., tetraalkylammonium hydroxides and piperidine).…”

Section: Introductionmentioning

confidence: 99%

“…Cyclohexanone oxime is a key intermediate in the production of ε-caprolactam (a precursor of nylon-6) through the Beckmann rearrangement . Conventional titanosilicate catalysts (Ti-MWW and TS-1) exhibit excellent performances in the liquid-phase ammoximation of cyclohexanone with ammonia and hydrogen peroxide to prepare cyclohexanone oxime .…”

Section: Introductionmentioning

confidence: 99%

Arginine-Assisted Hydrothermal Synthesis of Urchin-like Nb₂O₅ Nanostructures Composed of Nanowires and Their Application in Cyclohexanone Ammoximation

et al. 2018

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Urchin-like Nb2O5 nanostructures have been successfully synthesized by a novel and simple l-arginine-assisted hydrothermal method. They are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), nitrogen adsorption–desorption isotherms, thermogravimetric and differential thermal analysis (TG-DTA), and Fourier transform infrared spectroscopy (FT-IR). The results show that the urchin-like nanostructures are composed of nanowires with diameter less than 15 nm and possess a high specific surface area of 249.9 m2·g–1. Urchin-like Nb2O5 nanostructures have been used for the first time as a novel catalyst instead of conventional titanosilicate in the liquid-phase ammoximation of cyclohexanone. The as-prepared urchin-like Nb2O5 nanostructures exhibit high catalytic activity in cyclohexanone ammoximation. Under the optimal reaction conditions, the conversion of cyclohexanone and selectivity of oxime are as high as 98.0% and 88.9%, respectively. Finally, a possible formation mechanism of urchin-like Nb2O5 nanostructures is proposed.

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“…For example, silylation of NbO x /SiO 2 catalyst was found to improve ε-caprolactam selectivity and catalyst lifetime in the gas-phase Beckmann rearrangement. By passivating the more acidic, isolated-silanol sites with hexamethyldisilazane, the catalyst was more resistant to coking, and oxime hydrolysis, in the presence of water, could be suppressed [ 14 ]. Another common post-synthetic procedure involves the removal of framework atoms by treatment with an acid or base.…”

Section: Introductionmentioning

confidence: 99%

“…Whilst the resulting Nb/SiO 2 system lacks the inherent Brønsted acidity typically sought in Beckmann rearrangement catalysts, such activity can be developed by reacting the Lewis-acidic Nb centres with ethanol, in situ . Raman and FTIR studies have shown that the interaction of Nb=O groups with co-solvent creates active NbO 3 (OEt)OH species that confer Brønsted acidity for the rearrangement [ 14 , 59 ].…”

Section: Introductionmentioning

confidence: 99%

The Molecular Design of Active Sites in Nanoporous Materials for Sustainable Catalysis

2017

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At the forefront of global development, the chemical industry is being confronted by a growing demand for products and services, but also the need to provide these in a manner that is sustainable in the long-term. In facing this challenge, the industry is being revolutionised by advances in catalysis that allow chemical transformations to be performed in a more efficient and economical manner. To this end, molecular design, facilitated by detailed theoretical and empirical studies, has played a pivotal role in creating highly-active and selective heterogeneous catalysts. In this review, the industrially-relevant Beckmann rearrangement is presented as an exemplar of how judicious characterisation and ab initio experiments can be used to understand and optimise nanoporous materials for sustainable catalysis.

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NbOx/SiO2 in the gas-phase Beckmann rearrangement of cyclohexanone oxime to ε-caprolactam: Influence of calcination temperature, niobia loading and silylation post-treatment

Cited by 12 publications

References 43 publications

Understanding the Role of NbO_x on Pt/Al₂O₃ for Effective Catalytic Propane Oxidation

Understanding the Role of NbO_x on Pt/Al₂O₃ for Effective Catalytic Propane Oxidation

Arginine-Assisted Hydrothermal Synthesis of Urchin-like Nb₂O₅ Nanostructures Composed of Nanowires and Their Application in Cyclohexanone Ammoximation

The Molecular Design of Active Sites in Nanoporous Materials for Sustainable Catalysis

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NbOx/SiO2 in the gas-phase Beckmann rearrangement of cyclohexanone oxime to ε-caprolactam: Influence of calcination temperature, niobia loading and silylation post-treatment

Cited by 12 publications

References 43 publications

Understanding the Role of NbOx on Pt/Al2O3 for Effective Catalytic Propane Oxidation

Understanding the Role of NbOx on Pt/Al2O3 for Effective Catalytic Propane Oxidation

Arginine-Assisted Hydrothermal Synthesis of Urchin-like Nb2O5 Nanostructures Composed of Nanowires and Their Application in Cyclohexanone Ammoximation

The Molecular Design of Active Sites in Nanoporous Materials for Sustainable Catalysis

Contact Info

Product

Resources

About

Understanding the Role of NbO_x on Pt/Al₂O₃ for Effective Catalytic Propane Oxidation

Understanding the Role of NbO_x on Pt/Al₂O₃ for Effective Catalytic Propane Oxidation

Arginine-Assisted Hydrothermal Synthesis of Urchin-like Nb₂O₅ Nanostructures Composed of Nanowires and Their Application in Cyclohexanone Ammoximation