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本文用动态程序升温热脱附法研究了不同硅铝比的HZSM-5分子筛吸附氨的程序升温热脱附谱及其酸性质。结果表明,当硅铝比的效值小子47时,HZSM-5分子筛吸附氨的酸中心数与单跑中铝原子效呈线性递增关系。当硅铝比大于47时,则偏离了该线性关系。不同硅铝比的HZSM-5分子筛的酸强度随着硅铝比的下降而增强,它们的甲苯歧化活性与其单胞中铝原子数亦有线性递增关系,随着铝原子数的增加,催化活性提高,而选择性下降。
In this paper, the dynamic temperature programmed desorption method was used to study the temperature-programmed thermal desorption spectra and acid properties of ammonia adsorbed on HZSM-5 zeolites with different Si / Al ratios. The results show that the number of acid sites adsorbed on ammonia adsorbed by HZSM-5 molecular sieve increases linearly with the atomic effect of aluminum in the single run when the effective silica-alumina ratio is 47. When the Si / Al ratio is larger than 47, the linear relationship is deviated. The acid strength of HZSM-5 zeolite with different Si / Al ratio increases with the decrease of Si / Al ratio. Their toluene disproportionation activity also has a linear relationship with the number of aluminum atoms in the unit cell. With the increase of Al atom number, the catalytic activity Increase, while selective decline.