摘要
研究了不同硅铝比的HZSM-5和HZSM-11沸石对水、正己烷、环己烷、苯、间及对二甲苯的吸附性能。发现这两种沸石在所研究的P/P_s范围内,都是硅铝比高的其吸附量小,只是HZSM-11对正己烷、环己烷与对二甲苯的吸附例外。HZSM-5(60)吸附环己烷的量在P/P_s=0～0.25时为HZSM-5(400)的6～7倍,而HZSM-11(42)和HZSM-11(300)在P/P_s=0.08～0.20时吸附环己烷的量几乎一样。HZSM-5和HZSM-11对环己烷分子的空间阻碍效应有显著的不同。非极性的正己烷、对二甲苯及苯在四种沸石上吸附(20℃)时在很宽的P/P_s范围均符合吸附势理论,水、环己烷及间二甲苯在HZSM-5(60)和HZSM-5(400)上吸附时,除〔~1g(P_s/P)〕~2【0.5外也符合吸附势理论,可是水在HZSM-11(42)和HZSM-11(300)上吸附时,只是在0.5【〔1g(P_s/P)〕~2【2.5才符合。还发现HZSM-5(100)比HZSM-5(60)只有大得多的表面能量不均匀性。
Adsorption of water, n-hexane, cyclohexane, benzene, p-xylene and m-xylene on high silica zeolites HZSM-5 and HZSM-11 with different SJO2/A12O3 ratios was studied. It was found that the hydrophobicity of zeolites was increased with the increasing of SiO2/Al2O3 ratio, and the sequence was as follows: HZSM-5(400)>HZSM-11(300)>HZSM-5(60)> HZSM-11(42). In the range of P/PS studied, except the adsorption of n-hexane, cyclohexane and p-xylene on HZSM-ll, the higher the SiO2/Al2O3 ratio of HZSM-5 and HZSM-1, the smaller the capacity of adsorption of all adsorbates is. However, in the case of cyclohexane,the amount adsorbed on HZSM-5(60) in the range of P/PS= o to 0.25 was 6 -7 times larger than that on HZSM-5(400), and the amount adsorbed on HZSM-11(42) and HZSM-ll (300) in the range of P/PS=0.20-0.08 was almost the same. There was a stricking contrast in space hindrance of cyclohexane on HZSM-5 and HZSM-11. The adsorption of nonpolar compounds, such as n-hexane, p-xylene and benzene on the four zeolite samples conformed to the potential theory in a wide range of P/P s. The adsorption of H2O, cyclohexane and m-xylene on HZSM-5(60) and HZSM-5(400) also conformed to the theory except for Clg(-Ps/-P)]2<0.5. As for HZSM-11(42) and HZSM-11(300), only in case of 0.5<Clg(Ps/ P)]2<2.5, the H2O adsorption conformed to the theory. It was also found that the homogeneity of surface energy on HZSM-5(60) was much higher than that on HZSM-5 (400).
基金
国家自然科学基金
