CVD prepared mesoporous chromium catalysts for the synthesis of polyethylene

• Main Authors: Weng Weiting, 翁偉庭
• Other Authors: Li Kuo-Tseng
• Format: Others
• Language: zh-TW
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/50795629749006178491

碩士 === 東海大學 === 化學工程學系 === 93 === Abstract The purpose of this thesis is to prepare Cr-containting meosoporus catalysts ( Cr-MCM-41 and Cr-MCM-48) and Cr-SiO2 by chemical vapor deposition method, and to use the CVD prepared catalysts for ethylene polymerization. The polymerization was carried out in a slurry reactor. The supported catalysts were prepared with different CVD time and different dosage of CrO2Cl2. The effect of drying temperature and supports on the polymer yield where studied. We characterized the catalysts and polymers with a variety of techniques including BET, ICP-AES, TPR, SEM, TEM, DMA, DSC, DMA, XRD, FTIR and OM. We found that the catalysts with the CVD time of 3 hour had the best catalytic performances for ethylene polymerization, and the catalysts with Cr content of 5 ~ 6 wt % had the best polymer yield. We also found that MCM-41 was the best support with the best polymer yield occurred and the optimum drying temperature was 400℃.DSC results indicated that the change of supports had little effect on Tm and Tc of polymers. Optical microscope analysis indicated that the size of HDPE crystal decreased in the following order：Cr-SiO2＞Cr-MCM-48＞Cr-MCM-41. TPR results indicated the supported Cr catalysts can be reduced from Cr6+ to Cr3+ with a single reduction peak at 480~505℃.