PROCESS FOR PREPARING CAPROLACTAM BY BECKMANN REARRANGEMENT

Catalytically active sites for the beckmann rearrangement of cyclohexanone oxime to ?-caprolactam.
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applications of the Beckmann rearrangement, as caprolactam is the ..

Silicalite-1 was hydrothermally synthesized in the presence of different concentrations of Na+ using tetrapropylammonium hydroxide (TPAOH) as a template. The synthesis was followed by a base treatment. The silicalite-1samples were characterized using X-ray diffraction, scanning electron microscopy, N2 adsorption, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy and NH3 temperature-programmed desorption. The samples were used as catalysts for the vapor phase Beckmann rearrangement of cyclohexanone oxime. During the synthesis, the sodium ions were incorporated onto the silicalite-1 crystals, but were then removed by the base treatment. All the catalysts exhibited nearly complete conversion of cyclohexanone oxime to ?-caprolactam with selectivities grater than 95%. Addition of less than 2.5 mol-% Na+ (relative to TPAOH) did not influence the catalytic properties. However, for Na+ concentrations≥5 mol-%, the particle sizes of silicalite-1 increased and the catalytic activities decreased, which can be attributed to carbon deposition. The results in this work are of great importance for the polymer industry.

Active sites of a [B]-ZSM-5 zeolite catalyst for the beckmann rearrangement of cyclohexanone oxime to caprolactam.
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acid induces the Beckmann rearrangement to give caprolactam ..

Influence of Br and Na+ in synthesis of Silicalite-1 on catalytic performance in vapor phase Beckmann rearrangement of cyclohexanone oxime.

This is followed by a Beckmann rearrangement using oleum to yield caprolactam
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Beckmann rearrangement has been using reaction to synthesize N-substituted amides from keto-oxime. Industrially, the reaction is widely used in the synthesis of caprolactam as monomers for nylon. Strong acid such as sulfuric acid as well as high-temperature are required to proceed the reaction with a large amount of by-products. Ishihara reported the reaction using cyanuric chloride as catalyst. In this case, Beckmann rearrangement progresses under mild conditions. However, a detailed reaction mechanism is not clear. In the present study, the catalytic behavior of cyanuric chloride was investigated for Beckmann rearrangement of cyclohexanone oxime as well as cyclododecanone oxime. It was confirmed that HCl yielded during the reaction play a very important role in decreasing the activation energy of the rearrangement reaction.

Treatment of this oxime with acid induces the Beckmann rearrangement to give caprolactam ..
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