Beckmann rearrangement vapour-phase

Fe3+, La3+ and Ce3+ ion-exchanged MAPO-36 was prepared by wet ion-exchange method. The materials were characterized by XRD, TGA and TPD (ammonia). Lewis acid metal ions are suggested to remain as charge compensating MO+ species after calcination in ion-exchanged MAPO-36. Beckmann rearrangement of cyclohexanone oxime was studied over these catalysts in the vapour phase. 

Rare-earth exchanged [Ce ", La ", Sm"" and RE (RE = La/Ce/Pr/Nd)] Na-Y zeolites, K-10 montmorillonite clay and amorphous silica-alumina have also been employed as solid acid catalysts for the vapour-phase Beckmann rearrangement of salicylaldoxime 245 to benzoxazole 248 (equation 74) and of cinnamaldoxime to isoquinoline . Under appropriate reaction conditions on zeolites, salicyl aldoxime 245 undergoes E-Z isomerization followed by Beckmann rearrangement and leads to the formation of benzoxazole 248 as the major product. Fragmentation product 247 and primary amide 246 are formed as minor compounds. When catalysts with both Br0nsted and Lewis acidity were used, a correlation between the amount of Br0nsted acid sites and benzoxazole 248 yields was observed. 

As the Beckmann rearrangement is believed to be a typical acid-catalysed reaction, many researchers have reported the relationship between the vapour phase reaction catalysis and the acidity of the catalysts tested on non-zeolitic catalysts - i2s- i3i. 318-334 and on zeolitic catalysts Another interesting point for the heterogeneous gas-phase Beckmann rearrangement is the location of the reaction on the catalyst and different studies have been published ° . The outer surface of the catalyst particle seems to be the most probable place for the Beckmann rearrangement supported by the traces of reagents, and notable amounts of by-products found only in the outer layers of the zeolite crystal. Development of new and more efficient catalysts have also been reported " . ... 

Recently, the Sumitomo Chemical Co., Ltd. developed the vapour-phase Beckmann rearrangement process for the production of 8-caprolactam. In the process, cyclohexanone oxime is rearranged to e-caprolactam by using a zeolite as a catalyst instead of sulfuric acid. EniChem in Italy developed the ammoximation process that involves the direct production of cyclohexanone oxime without producing any ammonium sulfate. The Sumitomo Chemical Co., Ltd. commercialized the combined process of vapour-phase Beckmann rearrangement and ammoximation in 2003 ". 

The vapour phase Beckmann rearrangement reaction was carried out using a continuous flow system operated at ambient pressure. Helium was used to entrain the oximes into the vapour phase from a saturator (2.2 torr). The rearrangement of the oxime took place in the u-tube pyrex reactor loaded with 100 mg of catalyst. In normal operation the total gas flow rate was 30 ml min. On leaving the reactor the gas stream was cooled, the products were trapped and analysed by off-line gas chromatography. 

The stepwise conversion of N-cyclohexanone oxime into 6-caprolactam via the vapour-phase Beckmann rearrangement on a number of modified zeolite systems was studied by a variety of different solid-state NMR techniques, including N and CP MAS NMR spectroscopy. The zeolite materials are characterized by H, Si, and N MAS NMR... 

Sato H, Hirose K, Kitamura M, Nakamura Y (1989) A vapour phase Beckmann rearrangement over high-silicious ZSM-5, zeolites facts, figures, future. Elsevier, Amsterdam, pp 1213-1266... 

An integrated process, which combines catalytic EniChem TS-1, catalyzed direct ammoximation of cyclohexanone and Sumitomo Chemical vapour-phase Beckmann rearrangement, both exploiting MFI based zeolite-like materials, is now industrially used for greener caprolactam production from cyclohexanone without co-producing any ammonium sulfate (Fig. 15.2). ... 

The second step, the Beckmann rearrangement in the vapour phase, is based on the transposition of cyclohexanone oxime to the corresponding lactam, without the... 

Cesana, A., Palmery,S., Buzzoni, R.,ef a/. (2010).Silicalite-l Deactivation in Vapour Phase Beckmann Rearrangement of Cyclohexanone Oxime to Caprolactam, Catal. Today, 154, pp. 264—270. 

Fomi, L., Fomasari, G., Tosi, C., Trifirb, F., Vaccari, A., Dumeignil F., and Grimblot, J. Non-conventional sol-gel synthesis for the production of boron-alumina catalyst applied to the vapour phase Beckmann rearrangement. Appl. Catal. A Gen. 2003, 248, 47-57. 

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