The Beckmann rearrangement of cyclohexanone-oxime to ε-caprolactam over SBA-15 and MCM-48 mesoporous molecular sieves
| Autor: | Jung-Che Chang, 張榮哲 |
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| Rok vydání: | 2003 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 91 The Beckmann rearrangement of gaseous cyclohexanone -oxime(CHO) to produce ε-caprolactam(ε-C) has been studied using a fixed bed, integral flow reactor. Two types of solid acid catalysts were chosen viz. AlSBA-15(X) and AlMCM-48(X) where X denotes the SiO2/Al2O3 molar ratio. The catalytic properties, i.e., the structure、the morphology、 the pore structure、the surface area、 the SiO2/Al2O3 molar ratio and the acid amount were characterized by various methods of powder X-ray diffraction、scanning electron microscopy、transmission electron microscopy、surface analyzer、inductively coupled plasma-atomic emission spectrometer、temperature programmed desorption of ammonia and Fourier-transformed infrared spectroscopy. As the SiO2/Al2O3 molar ratio of these two types of catalysts decreases, the surface area diminishes but the acid amount increases. However, the hexagonal pore structure remains unchanged. In the reaction of CHO, the MCM-48 catalysts exhibit better catalytic activity than SBA-15 catalysts due to the three dimensional pore structure and larger surface area. The CHO conversion enhances with the reaction temperature and the contact time, where the ε-C selectivity exhibits the opposite trend. Both the catalyst stability and the ε-C selectivity greatly enhance by using ethanol and n-hexanol as the solvents due to the production of water vapor via dehydration. In the reaction of CHO under the conditions, viz. 350℃、the solvent of n-hexanol、W/FCHO = 74.6 g.h/mol and time on stream 130 h, both AlSBA-15(20) and AlMCM-48(20) attain ＞92 mol% CHO conversion and ＞91 mol% ε-C selectivity. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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