关键词: Y沸石改性, 稀土, 处理气氛, 水热处理, 变价, 分子筛, 催化剂, 氧化

Abstract:

Y zeolite, the main component responsible for the catalytic activity, selectivity, and stability of catalysts in fluid catalytic cracking (FCC), has long been used extensively in oil refining. The acidity and pore structure of Y zeolite determine its catalytic performance. To tune acidic property, post-synthesis treatment of NaY was carried out with two different modifying media, i.e., the calcination atmosphere of CeY and the ammonium ion exchange with different pH value. The structures and physical properties of the modified Y zeolites were characterized by IR spectroscopy, X-ray photoelectron spectroscopy (XPS) and low temperature N₂ physical adsorption; while their catalytic performance was evaluated on VGO oil in a fluidized bed reaction ACE unit. When Ce ion was chosen as the modifying medium, the distribution of various types of acids (Brønsted/Lewis acid) and the catalytic performance of USY zeolites could be controlled by changing calcination atmosphere. When cationic ammonium was used, the amount of Brønsted acid could be regulated and pore volume could be increased in the ultra stable Y zeolites by precisely adjusting pH value of the first ammonium ion exchange medium.

Key words: Y zeolite modification, rare earth, treatment atmosphere, steam treatment, valence transformation, molecular sieves, catalyst, oxidation