Deactivation and regeneration of titanium silicalite catalyst for epoxidation of propylene
Deactivation and regeneration of titanium silicalite catalyst for epoxidation of propylene
复制标题
DOI：
10.1016/j.molcata.2007.03.068
复制
发表时间：
2007-08-01
影响因子：
--
通讯作者：
Mi, Zhentao
中科院分区：
文献类型：
--
作者：
Wang, Qingfa;Wang, Li;Mi, Zhentao
用30 wt%的双氧水在异丙醇溶剂中在钛硅石（TS-1）沸石上连续环氧化丙烯，获得了对环氧丙烷良好的选择性和TS-1的稳定性。反应263h后，TS- I催化剂发生失活。采用550℃煅烧5 h、异丙醇溶剂洗涤或稀双氧水洗涤等方法对废催化剂进行再生，并对再生催化剂的活性进行了评价。采用扫描电镜、x射线衍射、傅里叶变换红外光谱、Si-29魔角自旋核磁共振、热重分析和Brunauer-Emmett-Teller方法对失活催化剂和再生催化剂进行了表征。采用溶剂萃取法对沉积在催化剂表面的成分进行收集，并采用气相色谱-质谱联用（GC-MS）对其进行分析。结果表明，焙烧和稀双氧水洗涤是一种高效的再生方法，经过这两种处理后，TS- I催化剂的催化活性基本恢复。异丙醇洗涤对TS- I催化剂的催化活性有微弱的恢复作用。TS-I型环氧化催化剂失活的主要原因是靶反应连续反应形成的大块有机副产物堵塞微孔，如环氧丙烷的二聚或低聚、环氧丙烷与异丙醇的醚化反应。此外，框架钛的浸出也导致催化剂失活。(C) 2007 Elsevier B.V.版权所有
Continuous epoxidation of propylene with 30-wt% hydrogen peroxide in isopropyl alcohol solvent over titanium silicalite (TS-1) zeolite was carried out and the good selectivity to propylene oxide and stability of TS- I were obtained. After the reaction of 263 h, the deactivation of the TS- I catalyst occurred. The spent catalysts were regenerated by calcinations at 550 degrees C for 5 h, washing with isopropyl alcohol solvent or washing with dilute hydrogen peroxide, and the activity evaluation of the regenerated catalysts were studied. The deactivated and regenerated catalysts were characterized by scanning electron microscopy, X-ray diffraction, Fourier-transform infrared spectroscopy, Si-29 magic angle spinning nuclear magnetic resonance, thermogravimetric analysis and Brunauer-Emmett-Teller method. The compositions deposited on the surface of the catalysts were collected by solvent extraction and were analyzed by gas chromatography-mass spectrometry (GC-MS). The results showed that calcination and washing with dilute hydrogen peroxide were highly effective regeneration methods and the catalytic activity of TS- I catalysts can be mostly recovered after these treatments. Washing with isopropyl alcohol had a subtle effect in recovering the catalytic activity of the TS- I catalyst. The major cause of the deactivation of the TS-I catalyst for epoxidation is blocking micropores induced by bulky organic by-products formed by consecutive reactions of target reaction, such as dimerization or oligomerization of propylene oxide, etherification of propylene oxide with isopropyl alcohol. In addition, leaching of framework titanium also contributes to the deactivation of the catalyst. (C) 2007 Elsevier B.V. All rights reserved.