稀土含量(La)对USY分子筛性能及其焦炭选择性的影响

摘要

采用XRD、固定床微反装置、快速精密定炭仪研究了用高温水蒸气法及稀土LaCl3改性NaY分子筛后分子筛的稳定性、活性及其焦炭选择性.结果表明,随着USY分子筛La含量的增加,其晶胞常数增大,活性增加,结晶度减小,老化后的533峰保留率降低,结晶度的降低并不是真正意义上的分子筛减少,而是稀土干扰导致的.综合比较稀土含量和晶胞的作用,可知晶胞大小可能是影响稳定性的最主要因素,而后才是稀土的影响.La含量增加,积炭含量增加,其焦炭选择性变差.%The techniques such as XRD, MAT, the rapid precision instrument for carbon were used to investigate the stability, activity and selectivity coke of the NaY molecular sieve modified with high temperature steam method and rare earth. The results showed that with the increase of the content of La,the crystal cell constant and activity of molecular sieve are all increased; the crystallinity and the 533 peak after aging of molecular sieve are all decreased. The crystallinity of molecular sieve decreased, which does not means molecular sieve decreased, but it' s rare earth interference. Comprehensive comparison the influence of rare earth content with crystal cell on the stability of molecular sieve, it can be seen that the crystal cell size may be the most important factor,and then it's the rare earth. With the increased of La content, the carbon content increased, and the coke selective becomes poor.