Synthesis And Application Of A Novel NaY/Kaolin Composite By The In-Situ Process

It is known that the activity and selectivity of the FCC catalyst tend to beimproved greatly with the increase of the Y-faujasite content. However, the increasedzeolite contents usually require sufficient binder to achieve good attrition resistance.The high content of binder usually leads to coating of the zeolite crystal surfaces andocclusion of potentially beneficial external acvtive sites. To avoid this disadvantage,in this paper, we used the in-situ synthesis method by pre-prepared kaolinmicrospheres and succeesfully prepared a Y/Kaolin microsphere composite with Y'srelative crystallinty above 40% and SiO₂/Al₂O₃ ratio of 4.83. XRD, N₂adsorption-desorption, SEM, FT-IR were employed to chacterize this composite.Physicochemical data indicated, compared to the nomal NaY, this microspherecomposite has more hydrothermal stable macro-pore structures, and the externalsurfaces of these Y zeolite crystallites are exposed and accessible to the feedmolecules. After modification and steaming treatment, a novel FCC catalyst wasprepared. The reaction data indicated that, compared to a commercial catalyst atsame operation conditions and similar coke selectivity, the.high zeolite Y contentin-situ catalyst have evident advantages on slurry yield (8.68% lower), conversionrate (10.33% higher) and liquid yield (7.6% higher). From PONA analyses, we canalso clearly see that the olefins content reduced greatly and RON improved markedlywith in-situ catalyst because of its higher zeolite content. Therefore, this novelin-situ catalyst with higher zoelite content has more adaptability for resid cracking.Then a novel FCC catalysts mixture was prepared by adding a semi-syntheticadditive catalyst with 35wt% of HZSM-5 to the above catalysts prepared by in-situ synthesis method. It was evaluated on Advanced Catalyst Evaluation (ACE) reactor. Catalytic cracking test showed, compared with a commercial propylene-improved FCC catalyst, the propylene yield ot our novel FCC catalyst is increased by 1.265% and propylene selectivity by 2.93%. At the same time, coke yield is decreased by 1.994% and total liquid yield is increased by 0.965%.