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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 adsorption heat of pyridine at 170 ℃ -270 ℃ on γ-Al 2 O 3 and Na × zeolites was measured by a differential thermal-chromatographic adsorption calorimetry system. It is confirmed that the acid center existing on the surface of γ-Al 2 O 3 is mainly the L acid center. When the temperature is increased, the amount of acid is decreased and the acid strength is weakened. The degree of weakening depends on the adsorption position. On the surface of Na × zeolite, there are two kinds of acid centers for irreversible and reversible adsorption of pyridine respectively. The stronger one is the non-activated L acid center and the weaker one is the activated B acid center. The effects of temperature changes on these two acid centers are different. Calculations show that the adsorption centers in the β cage and the faujasite cage are partially occupied by H 2 O molecules,