摘要
对六种不同性质的Y型沸石分子筛进行了吸附等温线的测定,对等温线的脱附支数据进行了微孔分析的计算。对相对压力P/P_0≥0.3(孔径r>1.5mm)段,可采用BJH法计算中孔孔径分布;对P/P_0≤0.3段,可采用MMP法计算微孔孔径分布。在MMP法中引入了N_2分子平均单层厚度t_m,减少了计算结果的波动。研究表明,HY具有r=1.5～2.4nm的二次孔,用EDTA和(NH_4)_2SiF_6脱铝的Y型沸石,具有更多更宽分布的二次孔,超稳Y的二次孔一直延伸到r>5nm。
Isotherms of N_2 adsorption on six different zeolite Y samples are determined. From these adsorption data, the calculation for micropore analysis is carried out. For the relative pressure P/P_0≥0.3 (pore radium r>1.5 nm), the BJH method is used for the calculation of mesopore size distribution, for P/P_0≤0.3, the MMP method is used for the calculation of micropore size distribution. The average value of N_2 molecule monolayer thickness t_m is used to get more reasonable results in MMP method. The results indicate that HY crystals have secondary pores of r=1.5～2.4 nm. The crystals of zeolite Y dealuminated by EDTA or (NH_4)_2SiF_6 have more secondary pores with a wide distribution. The ultrastable zeolite Y crystals remain a large portion of micropore and also have a considerable portion of secondary pore with much wider distribution, up to r>5 nm.
关键词
分子筛
孔结构
吸附
沸石
molecular sieve
pore structure
adsorption
zeolite
secondary pore
