Characterization of active sites working on FSM-16 during the vapor-phase Beckmann rearrangement of cyclohexanone oxime

Kinetic Study on Gas-Phase Beckmann Rearrangement of Cyclohexanone Oxime to ε-Caprolactam over a Silica-Supported Niobia Catalyst

“…It can be seen that selectivities to cyclohexanone, hexanenitile, and unidentified byproducts decrease with increasing alcohol chain length, whereas the other byproducts remain on an almost constant level. Cyclohexanone and hexanenitrile are typical byproducts originating from the cyclohexanone oxime decomposition catalyzed by residual (after the silylation posttreatment) isolated silanol groups on the catalyst surface. − Since both byproducts are decreasing with increasing alcohol C-chain length the above-mentioned hypothesis of a stronger adsorption of an alcohol with a high molecular weight on unselective sites is supported.…”

Vapor phase Beckmann rearrangement of cyclohexanone oxime over MCM-22

“…Accordingly, the selectivity of ε-caprolactam is dictated by the relative rates of rearrangement reaction of CHO oxime versus ring opening reaction of ε-caprolactam and hydrolysis reaction of CHO oxime. Shouro et al [41] reported that the desorption temperatures of ε-caprolactam, cyclohexanone and nitriles in mesoporous FSM-16 molecular sieve are 650, 550, and 550-650 K, respectively. Among them, ε-caprolactam has the greatest adsorption strength; such material can be further converted to undesired products before desorbing from the surface of the adsorbent.…”

Beckmann Rearrangement of 15N-Cyclohexanone Oxime on Zeolites Silicalite-1, H-ZSM-5, and H-[B]ZSM-5 Studied by Solid-State NMR Spectroscopy

“…The assignments of the signals at -199 and -275 ppm to the dehydration and hydrolysis products of cyclohexanone oxime is supported by the simultaneous increase of both signals upon heating the reaction mixture at 498 and 523 K (Figure 2h,i). As suggested by Shouro et al 11 for the Beckmann rearrangement of oximes on FSM-16-type materials, the preferred conversion of cyclohexanone oxime to 5-cyano-1-pentene on H-[B]ZSM-5 may originate from a reversible cleavage of the unstable -Si-OH-Bbridges in this catalyst.…”