| - Caprolactam, the raw material of nylon-6,is produced industrially by liquid phase Beckmann rearrangement of cyclohexanone oxime using concentrated sulfuric acid catalyst. However, the conventional process has several disadvantages such as the formation of low-value by-products ammonium sulfate, safety hazards, corrosion and environmental problems associated with the use of fuming sulfuric acid. In order to overcome these problems, this paper developed an environmentally friendly green technology to take place of the old one. The present studies have been made to use solid acid catalysts for vapor phase Beckmann rearrangement of cyclohexanone oxime.First, we have designed the solid catalysts for Beckmann rearrangement using H P zeolite. The initial material H P zeolite (Si/Al=14) were treated by three different post-synthesis modification methods. (1) HP zeolite (Si/Al=14) treated with diluted hydrochloric acid (HC1) in various concentrations, the corresponding ratio of Si to Al in P zaeolite is as followed 18,22,32 and 80, respectively. (2) Two types of P zeolite (Si/Al=14 and 80) supported boracic acid was prepared by the incipient wetness method using a known amount of an aqueous solution of boracic acid. (3) Two types of P zeolite (Si/Al=14 and 80) supported SiO2 was prepared by the chemical liquid deposition method using a known amount of tetraethoxysilane (TEOS). At the same time, the physical properties (Si/Al, specific surface area, pore volume) and the acidic property of part of the catalysts obtained are measured.Second, using the catalyst selected, the affect factors such as reaction temperature, the velocity of carrier gas and different solvent on the reaction are studied, the optimal reaction condition were temperature 350 , the velocity of carrier gas 30ml.min"' and solvent alcohol.The catalytic performance of modified and unmodified P zeolite were studied. The activity of H P zeolite is found very high. After 6 hour, the conversion of cyclohexanone oxime still remains 93.67%. During the process, the best selectivity is 44.45%. Using H P zeolite treated by hydrochloric acid of different concentration as catalyst, the conversion declined slightly, however, the selectivity is improved. The larger the value of Si/Al, the higher is the selectivity, and the highest selectivity is 59.51%.After P zeolite is modified by H3BO3 or TEOS, the conversion reduced by using them as catalyst. At the beginning of the reaction, the selectivity is relatively high, but it isn't steady and is declined along with time. Using the P zeolite loaded with boron which has larger value of Si/Al as catalyst, the selectivity and conversion are high. After Using the P zeolite modified by TEOS which has larger value of Si/Al as catalyst, the selectivity is high , but the conversion is a little low. On the P zeolite(Si/Al=80) loaded with 4wt% boracic acid, the reaction is carried out in 2h and the selectivity can reach to 63.99%. In conclusion, applying diluted hydrochloric acid as catalyst can improve the selectivity. On the P zeolite with large Si/Al, the optimal result can be obtained but the stability of the catalyst need to be improved.The change of the P zeolite(0.2MHCL) activity in 24h is also studied. The conversion with time of stream can be expressed as followed: x = 103. 69 xe-0.0218t,the deactivation factor b=0.0218s-1. After 24h, the activity of the deactivated catalyst would return to initial result in air flow for 2h at 500 . The deactivation of catalyst is caused by the deposition of coke on catalyst.
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