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

摘要：

Y型沸石作为FCC催化剂的主要活性组分，其酸性能和孔结构的改性效果直接决定了催化剂的性能优劣。选取酸性能为调变对象，分别采用两种不同的改性介质（CeY焙烧气氛和铵离子交换pH）对NaY沸石进行后改性处理。将所得的改性Y沸石进行了红外（IR）、X光电子能谱（XPS）和低温氮气物理吸附等表征分析。最后，使用真实油品VGO在固定流化床反应评价装置ACE上对改性样品的催化性能进行了评价。研究发现，选取Ce离子作为改性介质时，可通过改变后处理过程中的焙烧气氛来调变沸石不同酸类型的分布（Brønsted/Lewis acid，B/L），实现对应的USY沸石的催化性能的调控；选取铵离子作为改性介质时，适当地调节第1次铵离子交换pH的苛刻程度，能够在调变超稳Y沸石B酸量的同时提高Y型沸石的介孔体积。

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