In-situ Synthesis Of Small Size NaY Zeolites With High Framework SiO₂/Al₂O₃ Ratio Using Kaolin

Fluid catalytic cracking?FCC?process is a core technology of crude oil cracking,while FCC catalyst is the most depletion among all kinds of catalyst.However,the crude oil quality is becoming more and more serious.It if urgent to prepare new FCC catalyst with higher ability of heavy oil cracking.The small size Y zeolites with high framework SiO₂/Al₂O₃ ratio can fulfil the rigour condition of the catalytic cracking because of the fact that small size Y zeolites have very huge surface areas,high catalytic activity.The in-situ synthesized NaY zeolites using Kaolin have the advantages of small particle size,high stability of catalysis activity,rich meso/macro porous structure,excellent mechanic properties of martrix and good performance of resistance to heavy metal pollution.In the preliminary work,we have prepared small size NaY zeolites with high framework SiO₂/Al₂O₃ ratio by directive synthesis proccess.The main goal of this paper is to prepare small size NaY zeolites with high framework SiO₂/Al₂O₃ ratio by in-situ synthesis using Kaolin as raw materials,aimming to provide reseach basis of synthesizing new FCC catalyst.The main research results of this paper are as followed:?1?The investigation of the optimal calcining condition of Kaolin show that,the availability of Al₂O₃ is about 96% in Suzhou Kaolin calcined among 700? to 850?,and the availability of SiO2 is about 70% at 950?.The availability of SiO2 and Al₂O₃ is about 50%⁶0% and 8%¹2% respectively in Pucheng Kaolin lower than Suzhou Kaolin.?2?Small size?300⁶00 nm?NaY zeolites with high framework SiO₂/Al₂O₃ ratio?5.7⁶.0?were synthesized by a one-step hydrothermal method using calcined Suzhou Kaolin.The results show that,with the raising of the addition of SDA,the synthesis induction period was shortened.The content of NaY zeolites in product can be changed by different Kaolin/meta-Kaolin ratio in raw materials.The framework SiO₂/Al₂O₃ ratio of NaY samples is increased to 6.2⁶.3 with the optimal synthesis proccess.?3?Small size NaY zeolites with high framework SiO₂/Al₂O₃ ratio on Suzhou Kaolin spheres were prepared by an in-situ synthesis proccess.The framework SiO₂/Al₂O₃ ratio of samples was 5.7⁵.9,the relative crystallinity was about 70%,the particle size was smaller than 200 nm.The influence of ageing time was investigated.The results show that,with the raising of ageing time from 6 h to 12 h,the synthesis speed is accelerated and the relative crystallinity is increased,but the stable period was shortened.The best ageing time is 8 h¹0 h.