The Optimization Of The Synthesis Conditions For Preparing Zeolite Y Microspheres And The Study Of The Performance Of The Catalytic Cracking Catalysts

Semi-synthesis and in-situ crystallization have been widely used to prepare the fluid cracking catalysts. In the semi-synthesis, zeolite is prepared first, and then mixed with kaolin and binder for molding by spraying. The semi-synthetic catalyst microsphere has a diameter size of 60μm, followed by calcination and crystallization. Optimization of the crystallization conditions is extremely important to obtain high zeolite content and competitive catalytic performance.The thesis studied the relationship between the chemical composition and the zeolite content in the in situ microspheres using the uniform design method, aiming to get optimizing crystallization conditions. Compared to the domestic FCC catalyst, the NaY content was enhanced by 13%. The as made FCC catalyst was evaluated in the reaction.The mathematical model of the crystallinity of zeolite Y as function of the ratio of the reactive Na2O and SiO2(X) was established using the curve-fitting method. The obtained curves were Y= 17.0203 X-30.4817 (X= 3.5-4.2), Y=-24.8765 X+152.9557 (X 4.2-5.5), Y=-8.20107 X+82.5337 (X= 5.2-6.1). When the X was in the range of 4.2 to 5.5, it can be seen that it has a high influence on the crystallinity.The REHY FCC catalyst was prepared after ion exchange and calcination of the NaY microspheres. The acidity of the prepared catalyst and the commercial catalyst were measured. The results showed that the acidic strength of the catalyst prepared by TPD method was indicated at 200℃(L acid) and 400℃(B acid), closed to those of the commercial one(QD-C). The total acid amount of the prepared catalyst was 2.17 mmol/g, compared to 0.50 mmol/g for JK-B,1.98 mmol/g for QD-C and 0.84 mmol/g for ZH-D.The total pore volume of HD-A is 17.3%(Drop Method) and 6.7%(BET Method) higher than those of the commercial catalyst QD-C. In addition, the total surface area, the surface area of mesopore, the surface area of microporous, the MAT activity, the vanadium pollution activity, the total liquid yield and the gasoline increased,40%,79%,21%(12 units absolute), activity by 64%(17 units absolute activity) of 5000μg·g-1,3 units, and 1.7 units, respectively. The overall performance of HD-A was better than commercial catalyst QD-C.