摘要
用自行设计的差热-色谱吸附量热系统测定了170℃—270℃吡啶在γ—Al_2O_3和Na×沸石上的吸附热。证实了γ—Al_2O_3表面上存在的酸中心主要是L酸中心,温度升高时,酸量减少,酸强度减弱,减弱的程度因吸附位置的不同而不同。在Na×沸石表面上,存在两种对吡啶分别呈不可逆与可逆吸附的酸中心,较强的一种是非活化的L酸中心,较弱的一种是活化的B酸中心。温度变化对这两种酸中心的影响各有不同。计算表明,β笼和八面沸石笼中的吸附中心部分地为H_2O分子所占据、
The differential heats of adsorption for pyridine on γ-Al_2O_3 and NaX zeolite in the temperature range of 170℃ -270℃ have been measured by a DTA-GC adsorption calorimetric system which was designed by us. It is verified that the acidic sites on the surface of γ-Al_2O_3 are mainly L-acid sites. The acid amounts would reduce and the acid strength would decrease as the temperature is raising. The decreasing extent of the acid strength ato ne adsorption site is not the same as that of the acid stre- ngth at another. There are two types of acidic site which adsorb pyridine irreversibly and reversibly differently on the surface of NaX zeolite. The stronger type is non-active L-acid site. The weaker one is active B-acid site. The influence of the temperature variation upon the two types of acidic site is not the same either. The calculation result shows that the total adsorption sites in β-cages and octahedral zeolite cages are partly occupied by H_2O molecules.
出处
《贵州科学》
1990年第3期67-72,共6页
Guizhou Science
