The Study On Si-Al Gel And Kaolin As Raw Material Hydrothermal Crystallization Synthesis Of Multi-level Channel Catalytic Materials

FCC catalyst is the core technology of the modern catalytic cracking oil refining,NaY zeolite is still the main active component in all components of the FCC catalyst.FCC catalyst technology around the in situ crystallization technology expanded, thecatalyst synthesized kaolin in situ crystallization technology is the most commonlyused in catalytic cracking catalyst synthesis. How to synthesize contain welldeveloped pore structure, moderate acidic activity center is the direction ofdevelopment of the FCC catalyst technology. This text takes Si-Al gel as a template,add to the kaolin slurry, after spray-dried form microspheres, the microspherescalcined at different temperatures, respectively, containing the active silicon andactive alumina, Microspheres containing the active silicon as a silicon source,Microspheres containing the active alumina as aluminum source, and then add sodiumsilicate, directing agent and lye, according to a certain proportion in situ crystallized,get the catalyst containing NaY molecular sieve, and then modified by rare earth in afixed fluidized bed device （FFB） on feedstock oil for catalytic cracking reactions, andinvestigate its catalytic cracking performance. The main work is as follows:Firstly, Based on the literature to study the conditions of formation of the Si-Algel, Through the experimental investigation Si-Al gel in addition amount of kaolinslurry, experimental results show that Si-Al gel addition amount up to20%. Kaolinslurry exceeds this value can not be too thick to spray forming.Secondly，Study synthetic system of the H₂O/Na₂O, Na₂O/SiO₂and SiO₂/Al₂O₃to synthesis of NaY zeolite in situ crystallization influence to determine the bestproportion of the crystallization. The results show that when H₂O/Na₂O for50,Na₂O/SiO₂for0.6, SiO₂/Al₂O₃were the14or so, the synthesized product ofcrystallization have a good relative degree of crystallinity.Thirdly, Different crystallization products by N2adsorption and desorptioninstrument on the characterization of pore size distribution, results confirm that afterjoining the gel, the product of crystallization in the mesoporous range of pore volumeand surface area are more substantial rise in referral, the pore size distribution moreconcentrated; when added gel ratio of10%, the crystallization products ofmesoporous pore volume and surface area of the largest, declined at20%.Fourthly, By tracking the concentration of the active component in the systemliquid of in-situ crystallization process under different crystallization time, we find that: one hour after the start of the crystallization reaction, SiO₂concentrationsincreased in the liquid phase, to two hours, the concentration of SiO₂remainedwithout a significant decrease or increase in the fluctuations, maintained at about190g/L, began to decline after the crystallization of20hours; Al₂O₃concentrationhas been hovering in the low concentration range; and Na₂O concentration decreasedgradually. This is consistent with the formulation of the active component in theliquid phase transition mechanism.Fifthly. For detect in kaolin microspheres in situ crystallization process, theexperimental results indicate that: When to join the Si-Al gel ratio of10%, Kaolinmicrospheres began to occur in situ crystallization of the short est, When to join theSi-Al gel ratio of5%and20%, Kaolin Microspheres in situ crystallization started tooccur the same time, and not a member of the Si-Al gel microspheres began to occurin situ crystallization of the longest. Because synthetic conditions are exactly thesame as this system, and with different Si-Al gel kaolin microspheres by lyeextraction, the surface area in the mesoporous range respectively for47.7m2/g,67.5m2/g,81.7m2/g and59.2m2/g. This description of the nucleation of zeolite adsorptionand reorganization of the components in the liquid phase by the kaolin microspheres,within the microsphere surface and the liquid interface.Sixthly, For the synthesis of the four catalysts in raw material of oil crackingreaction, its catalytic cracking performance results showed that: When to join theSi-Al gel ratio of10%, synthesized catalysts than not a member of gel catalyst in theconversion rate of the atmospheric residue of2.26percentage points higher，3percentage points higher on the yield of gasoline. and heavy oil yield decreased by1.58percentage points, show that the catalyst has a fine tower base oil crackingcapacity and good selectivity. This is precisely because that join the Si-Al gel to amodulation of the pore structure of the catalyst, make the catalyst has the idealdistribution of the pore at all levels.