| Fluid catalytic cracking (FCC) process is a core technology of crude oil cracking. However, the crude oil quality is becoming more and more serious. It is urgent to develop novel FCC catalysts for catalytic cracking of heavy oil. This requires that the FCC catalyst active component-Y zeolites not only possess the characteristics of small cryatal size, but also possess higher skeleton silica alumina ratio. Small crystal size NaY with high silica alumina ratio (HSY) had been synthesized by using cheap industrial raw materials without the presence of chemical additive via non-template method. Under the same reaction conditions, the catalytic cracking activity of HSY is higher than the industry USY. Therefore, there is a good application prospects of HSY. The main goal of this paper is to complete the scale up synthesis (2L and10L scale) of HSY and explore the methods and conditions of the mother liquor recycling and reuse technology. Moreover, to provide the basis for the development of a new generation of FCC catalyst, hydrothermal treatment conditions and methods of HSY was studied. In this paper, the main research results are as followed:(1) Under a laboratory scale, different raw materials were studied. The results indicate that HSY can be successfully synthesized by sodium silicate B, C and D. On this basis, under a2L and a10L scale up synthesis, the results show that the synthesis process of2L scale does not appear significant amplification effect; And a certain degree of amplification effect appears in the synthesis of10L scale. The silica alumina ratio of HSY-3samples synthesized under different scales are around5.5, and that of HSY-4are around6.3. The relative crystallinity of both of them is more than90%. The particle size is about300nm.(2) Neutralization precipitation method was applied to recover the unavailable silicon source in the mother liquor of HSY-4. The pH value, concentration of aluminium sulphate and the gel temperature were studied. The results show that under pH of6at60℃, with an aluminum sulfate concentration higher than5.8%, the recovery rate of the silica source in crystallization mother liquor (including secondary water lotion) is about100%. HSY-4is synthesized with part of recycling aluminum silicon glue. The skeleton silica alumina ratio of the products is6.4, and relative crystallinity is more than100%, the particle size is about300nm. Full recycle of silicon source was realized basically.(3) The regular patterns of the hydrothermal treatment of HSY-4was studied. The ammonium exchange numbers (content of Na2O), hydrothermal treatment temperature and time were inveatigated. The results show that Na2O can inhibit the action of the dealumination. The dealumination reaction mainly occurs within the initial2h in the hydrothermal treatment. With prolonging the hydrothermal treatment time, and improving the hydrothermal treatment temperature, the skeleton silica alumina ratio of the samples are evaluated. After the hard hydrothermal treatment condition, skeleton silica alumina ratio of HSY-4is17.2, the relative crystallization degree is up to93%, which indicates the HSY-4has a high stability.(4) The catalytic cracking performance of HSY-4-A with hydrothermal deactivation at800℃for17h was evaluated. The three isopropyl benzene was choosed as model compounds. The results show that the average cracking rate of HSY-4-A is above20%than the industrial USY. It indicates that HSY-4-A has strong ability of catalytic cracking of macromolecular reactants. |
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