用正电子研究水热处理对稀土Y型沸石结构的影响

Effect of hydrothermal modification on the structure of REY zeolite studied by PAS

本文用正电子湮没谱学研究了水热处理温度等对稀土Y型沸石(REY)结构的影响。测量了REY沸石分子筛先经150℃预脱水、再经不同温度(300-800℃)下水热处理1 h后的正电子寿命谱,所有谱中都出现了5个寿命分量,其第5寿命值及其相对强度与生成二次孔的大小和数量相关。实验表明在一定温度范围内REY经水热处理后都能产生二次孔,其中水热处理温度为500℃,处理时间为1 h,所产生的二次孔不仅数量多而且孔径大。并讨论了不经预脱水处理的水热处理对REY结构的影响。

The effect of temperature of the hydrothermal modification on the structure of Rare-earth Y zeolite (REY) was studied by positron annihilation spectroscopy. We measured the positron lifetime spectrum as a function of the temperature (300-800℃) of one hour hydrothermal modification for the REY zeolite after through pre-heated dehy-dration at 150℃. All lifetime spectra could be resolved into five components. The fifth lifetime component and its in-tensity were found to be related to the size and number of the secondary pores. The experimental results showed that the secondary pore in REY zeolite was produced by hydrothermal modification in some temperature range, and the largest size and the greatest quantity of the secondary pores were observed in the sample treated at 500℃ for 1 hour. The effect of hydrothermal modification on REY zeolite without pre-heated dehydration was also discussed.