Optimum Conditions for Oxychlorination Redispersion of Supported Pt catalysts

• Main Authors: Chia Chyi Chang, 張家棋
• Other Authors: Jen Ray Chang
• Format: Others
• Language: zh-TW
• Published: 2004
• Online Access: http://ndltd.ncl.edu.tw/handle/76839471021851516073

碩士 === 國立中正大學 === 化學工程研究所 === 92 === Supported platinum catalysts have long been used to in refinery and petro-chemical industry. However, because noble metal catalysts are very expensive. They have to be regenerated when the catalysts were deactivated. The regeneration of the catalyst involves two steps : elimination of cake, and metal redispersion. Up to now, the mechanism of redispersion is still in debate. Therefore, the main purpose of this project is to prepare a full redispersed pt catalysts and by which to investigate redispersion mechanism thereby to explore optimum redispersion condition and to increase the benefit of refining and petro-chemical industry. Extended-X ray absorption fine structure (EXAFS) spectroscopy, which has been shown to be the only tool being able to characterize the microstructure of the species formed during the redispersion process and the experimental results indicate that by oxychlorination, aggregated Pt clusters can be disrupted to smaller clusters and the surface intermediate can be formulated as Pt(OCl)3Cl3/Al2O3. By EXAFS、FTIR and TPR, the reduction kinetics of the intermediate and optimum reduction temperature has been obtained. Moreover, XANES、EXAFS and CO chemisorption have also been used to characterize sintered catalyst with different redispersion conditions like oxychlorination reaction time,Air/EDC ratio,WHSV, and the results indicate that the best redispersion conditions are redispersed the sample at mole ratio of Air to EDC of 30, WHSV(weight hourly space velocity) of 0.05hr-1, temperature of 530℃ for 18hr.