Effect of ZSM-۵ seeds in the synthesis of SAPO-۳۴ catalyst in methanol tolight olefins

SAPO-۳۴/ZSM-۵ catalyst has been synthesized by using different amounts of processedZSM-۵ seeds at ۱۰۰°C in order to control the selectivity of light olefins and increase the lifetime.The catalytic properties and performance of SAPO-۳۴/ZSM-۵ were different compared toconventional SAPO-۳۴. The synthesized samples were characterized using XRD, FESEM, FTIR,BET, and NH۳TPD. The effect of seed amount did not follow the same trend in the entire testedrange. The XRD results showed that with the addition of seed, the crystallinity and size of thecrystallites increased, at the same time, an increase in the particle size was observed in the FESEMimages. The SAPO-۳۴/ZSM-۵ catalyst with ۶.۲۵wt% seeds, which has the smallest crystallite sizein catalysts with seeds, showed the highest stability (۷۰۰ min) and selectivity to light olefins(۸۹.۸۴%) compared to other samples; Also, according to the results obtained from NH۳TPDanalysis in this sample, the strength of strong acid sites and the amount of total acidity is less thanother samples, which has reduced the formation of coke and longer lifetime of this sample.

کلیدواژه ها:

Methanol to light olefin ، ZSM-۵ seeds ، SAPO-۳۴ ، SAPO۳۴/ZSM-۵