Earth With Nay Zeolite Cake Exchange Law

Zeolites REY, characterized by the excellent hydrothermal stability and cracking activity, have become an important active group of the FCC catalyst. Generally, zeolites REY are prepared by the process of twice ion-exchanges and twice calcinations. These two times of ion-exchange processes are all executed in the tanks under the condition of continuous agitation and constant temperature. Then, zeolites are separated by the plate-and-frame filter or horizontal vacuum belt filter. This process is complicated, and both of the substance and energy consumption are fairly considerable.The horizontal vacuum belt filter has been successfully applied in the continuous ion-exchange of NH4NaY. According to the character of the RE/NaY ion-exchange, a new process is put forward that the vacuum belt filter is applied in the continuous ion-exchange of RE/NaY.By the experimental method. the continuous ion-exchange on the belt filter and the batch ion-exchange in the tanks were respectively simulated and compared. For the same exchange degree of RE, the RE203/NaY(weight) ratio of the continuous ion-exchange is less than that of the batch ion-exchange, otherwise, the former's water expense is lessAbout the Continuous ion-exchange on the belt filter, it was found that the effect of the operating factors, such as the temperature, the vacuum degree and the concentration of the REd3 solution, on the exchange degree of RE is not obvious. Butthe temperature affects the filtration velocity remarkably. The higher the temperature, the faster the velocity. However, the over fast velocity would easily cause the cake to crack or take air into the cake which would decrease the efficiency of the ion-exchange and washing processes.The counter-exchange pHenomenon was studied during the latter washing process by NH.I~ solution. Not only the RE203 content of REY by the continuous ion-exchange but also that by the batch ion-exchange decreased by 1%(weight) more or less, moreover both of the Na20 content decreased to some extent. However, the RE203 content of REY by the continuous ion-exchange is higher than that by the latter, and the Na20 content is also less.With the evaluation by MAT, there was roughly no difference between these two zeolites REY's catalysts on the cracking activity which had been aged in 100% steam at 800 ~C for 4h. But the active stability of zeolites REY by the continuous ion-exchange is a little better.Otherwise, several process schemes were inspected contrastively. According to the lifetime of the belts, the deposit formed on the belt was discussed by means of SEM-EDS. It was concluded that the deposit consists of the RE and zeolites particles. Finally, the optimum process scheme to prepare zeolites REY on the belt filter was brought up.