水热脱铝法制备超稳Y型沸石的影响因素

STUDIES ON FACTORS AFFECTING HYDROTHERMAL DEALUMINATION DURING ULTRASTABLE ZEOLITE PREPARATION

对以NaY为原料、用水热脱铝法制备超稳Y沸石(USY)过程中钠离子交换深度、超稳化过程的温度和压力对USY性质的影响进行了研究.结果表明,Al—O键在500℃水热条件下可以较快地水解.钠离子可以阻止脱铝反应.当超稳化处理温度升高时,脱铝深度增加,USY的酸量下降.超稳Y沸石的结晶度随超稳化压力的增加而降低.高硅铝比的超稳Y沸石具有好的热稳定性和抗积炭性.通过调节超稳化处理过程中的控制因素而改变USY的硅铝比,可对表面酸性产生有效的调变作用.

The starting material for the preparation of ultrastable Y zeolite (USY) is NaY zeolite. The factors affecting the properties of USY: the extent of sodium ion exchange, the steam temperature and pressure during hydrothermal ultrastable treatment were studied. The result showed that hydrolysis of the Al -O bonds proceeded quickly when heated above 50℃ with steam. Sodium ions inhibited the dealumination reaction. The extent ?of. dealumination increased and the acidity of USY decreased with increasing treatment temperature. The crystallinity of the products decreased with increasing treatment pressure. The USY zeolite with a high ratio of SiO2, to A12O3, has high thermal stability and low coking rate in hydrocarbon cracking. Effective surface acidic accommodation can be realized by changing the SiO2/Al2O2 ratio of USY zeolite during its preparation.