稀土含量对超稳Y沸石的酸性及裂化活性的影响

EFFECT OF RARE EARTH CONTENT ON THE ACIDITY AND ACTIVITY OF ULTRASTABLE Y ZEOLITE

本文研究了不同稀土含量的超稳Y沸石的酸性、正己烷裂化活性、水热稳定性和氢转移反应。发现强酸中心、弱酸中心和正己烷裂化活性都随着沸石中稀土含量的增加而增加,沸石的酸性与正己烷裂化活性呈很好的对应关系。沸石中稀土含量越多,它们的水热稳定性越高。同时沸石的酸性随水热处理温度的提高而减小;而且氢转移反应随着沸石的酸性降低而变慢,但烯烃选择性却增加。

The acidity, activity of n-hexne cracking, hydrothermal stability and hydrogen transfer reaction of the ultrastable Y zeolites with different RE contents have been studied by pulse microreactor-chromatographic technique and temperature program desorption. It is found that both the strong acid sites, the weak acid sites and the activity of n-hexane cracking increase with increasing RE content in HUSY. The acidity of zeolite correlates well with the activity of n-hexane cracking. It is also observed that the higher the RE content of zeolite, the higher the hydrothermal stability, Furthermore, the acidity of zeolite decreases with increasing steam treatmenr temperature. As the acidity of zeolite is lowered, the hydrogen transfer reaction becomes slow and the olefine selectivity increases.