低钠含量LaHY分子筛的制备、表征及催化性能

Preparation,characterization and catalytic performance of LaHY zeolite with low sodium content

以不同的HY沸石分子筛为基质,采用等体积浸渍法将镧离子引入HY分子筛中,得到低钠含量LaHY分子筛,并采用X射线荧光(XRF)、X射线衍射(XRD)、比表面积(BET)、氨程序升温脱附(NH3-TPD)等方法对催化剂进行表征,考察了催化剂对正己烷的催化裂解性能。结果表明,LaHY分子筛中钠含量越低,其相对结晶度和晶胞参数越小,而总酸量和比表面积越大,催化活性及烯烃选择性也越高。当HY焙烧温度为550℃时,经La改性后得到的LaHY分子筛,其相对结晶度、总酸量和比表面积最大,催化活性最高,但温度升高至600℃时,LaHY分子筛的物化性质和催化性能都降低。

The catalysts of La supported on different HY zeolites was prepared by isovolume impregnation method. The catalysts were characterized by X-ray fluorescence （XRF）, X-ray diffraction （XRD）, BET surface area measurements, and NH3-temperature programmed desorption, and evaluated for the catalytic cracking of n-hexane. The results show that the lower Na content, the lower crystallinity and cell parameters of LaHY zeolite obtained, while with the increase in the total acid amount and specific surface areas, the catalytic activity and the selectivity of LaHY zeolite to olefin increased. The LaHY zeolite has higher crystallinity, total acid amount , specific surface areas and the catalytic activity at higher temperature. When the temperature was higher than 550℃, the physichemical and catalytic performance of LaHY zeolite were decreased.