Novel synthesis of -caprolactam from cyclohexanone-oxime via Beckmann rearrangement over mesoporous molecular sieves MCM-48 |
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Authors: | J-C Chang A-N Ko |
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Affiliation: | Department of Chemistry, Tunghai University, Taichung, Taiwan |
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Abstract: | Vapor-phase synthesis of -caprolactam ( -C) from cyclohexanone-oxime (CHO) has been studied at 1 atm and 300–400 °C using SiMCM-48 and AlMCM-48(X) with Si/Al molar ratios X in a fixed-bed, continuous flow reactor. The catalysts were characterized with ICP-AES, XRD, TEM, FT-IR, N2-adsorption, 27Al and 29Si MAS NMR and TPD of ammonia. An increase of X value in AlMCM-48(X) enhances both the BET surface area and the unit cell parameter but diminishes the acid amount. In the reaction of CHO, benzene, toluene, ethanol and 1-hexanol were utilized as solvents. The CHO conversion increases with the reaction temperature, whereas the -C selectivity exhibits the opposite trend due to side reactions. The catalyst stability is greatly enhanced by using ethanol and 1-hexanol as the solvents due to their production of water vapor via dehydration. Excellent catalytic performance of AlMCM-48(10) is attained at 1 atm, 350 °C and W/Fc 74.6 g h/mol by using 1-hexanol in the feed; the CHO conversion and the -C selectivity exhibit higher than 99% and 90%, respectively, during at least 130 h process time. |
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Keywords: | sciencedirect com/scidirimg/entities/25b -Caprolactam" target="_blank">gif" alt="var epsilon" title="var epsilon" border="0">-Caprolactam Cyclohexanone-oxime MCM-48 Beckmann rearrangement |
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