LAY Molecular Sieve Research And Analysis Of Industrial Production Processes

As the quality of crude oil getting worse and hydrocracking refining technology developing rapidly, the hydrocracking catalyst is called for higher quality increasingly. LAY zeolite, mainly used for producing hydrocracking catalyst because of high activity and stability due to its medium lattice constants, high crystallinity, silicon-rich skeleton, low sodium oxide, is produced and used widely. To ensure the LAY zeolite product’s quality and the stability of it, various factors impacting on product quality in the three processes of filtration, hydrothermal calcination and post-modification has been studied combining with the modification mechanism of Y zeolite in this paper.The producing techniques are improved accordingly. What’s more, through the techniques of dust control and comprehensive utilization of water, pollution emissions is controlled effectively. The whole technology has become environmental-friendly.In the filtering process, the empacts of the flow and temperature of the NH4Cl solution for ions exchange, the cake thickness and the series of washing and exchange on the effect of exchange is studied. The optimized conditions of the process are listed as follows. The NH4Cl solution has flow of 0.2～0.25m3/h and temperature of 65～70℃; cake thickness is controlled between 8～12mm; exchange series in filter is two, washing series is three.The impact of relative crystallinity and ratio of Si to Al of the NaY and type of the ammonium salt used in the ion exchange process, the humidity of materials calcined and the calcination temperature on the effect of hydrothermal calcination is studied. The results show that high ratio of Si to Al of the NaY can help to ensure the quality of products calcined; the humidity of materials calcined hasn’t evident influence on the effect of calcination; calcination temperature should be controlled around 550℃; NH4NO3 has little impact on the calcination, while (NH4SO4 can’t meet the demand of production; when NH4Cl is used, the exhaust must be cleaned up before adding material calcined.By studying the post-modification process of USY zeolites obtaining from calcining, a technique called "second dealuminum" is put forward to ensure the product quality of LAY zeolite. A mixture of fluosilicic acid and diluted nitric acid is used in the "Second dealuminum" technique. The dosage and adding speed of it should be controlled when operating.With the improvement of the calcining exhaust system and the flash drying system, the problem of dust pollution is solved, while the product yield and the productivity of devices are improved at the same time. The water consumption is reduced up to 50% or more through rebuilding pipelines of chemical water and reusing filtrated water, that produces good social and economic benefits.