稀土离子半径对Y分子筛抗Ni性能的影响

摘要

CeY,NdY and HoY zeolites were prepared by liquid phase ion exchange method,and the Ni contamination was carried out by Mitchell impregnation method.The acid properties of the catalysts were characterized by ammonia temperature programmed desorption (NH3-TPD) and in situ pyridine infrared spectroscopy.The results indicate that REY zeolite has a better ability to inhibit the destruction of the Br(o)nsted (B) acid sites with the decrease of the radius of rare earth ions.Further acidity and activity were associated,it was found that the catalytic cracking activity of REY zeolite was increased with the decrease of the radius of RE.And the content of gasoline in the reaction liquid phase increased with the decrease of the radius of RE ions in Ni/REY zeolite catalyst.So the smaller the RE ionic radius,the better the nickel tolerance of REY zeolite.%采用液相离子交换法制备了CeY、NdY、HoY分子筛,并通过Mitchell等体积浸渍法对其进行Ni污染.运用氨气程序升温脱附(NH3-TPD)和原位吡啶红外光谱技术(In situ Py-FTIR)对其酸性质进行表征,采用微反应活性评价装置考察其抗Ni性能.结果表明,随着稀土离子半径的减小,稀土改性Y型分子筛抑制Ni破坏其B酸中心能力逐渐增强.进一步将酸性关联活性后发现,经Ni污染后REY分子筛的催化裂化微反应活性亦随着稀土离子半径的减小而逐渐增强,且反应液相产物中汽油质量分数随Ni/REY分子筛催化剂中RE离子半径的减小而逐渐增加.RE离子半径越小的REY分子筛抗Ni性能越好.