跨越临界温度的分子筛吸附——微孔体积填充理论的适用性

Applicability of the Theory of Micropore Volume Filling on Zeolite NaX under and above Adsorbate Critical Temperature

用高真空重量法测定了NaX分子筛对不同吸附质NH_3,H_2O,C_2H_5OH等的吸附等温线,用微孔体积填充理论对吸附等温线进行非线性拟合,得到满意结果。表明该理论不但可扩展到以静电场为主的吸附体系,还可适用于吸附温度高于吸附质临界温度的吸附体系。计算结果表明,NaX吸附不同吸附质测得的极限空腔体积基本相同,且与结构分析得到的空腔体积一致,进一步表明微孔体积填充理论对该体系的适用性,计算了各种吸附质的极限吸附量,以及某填充度下的微分吸附热随着温度的变化趋势,可为固体吸附式制冷系统的设计与制造提供理论依据及有关参数。

The isotherms of adsorption of NH_3, H_2O and O_2H_5OH on NaX zeolites were detemined.The applicability of the theory of micropore volume filling to the researched adsorption systems was evaluated by the method of nonlinear regression.It appears to be satisfactory not only for the description of adsorption systems mainly depending on electrostatic interaction, but also for the description of adsorption systems whose adsorption temperature is higher than the critical temperature of the adsorbates.The calculating results indicated that the values of the limiting volume of adsorption space W_0 were same in the main for the adsorption of different adsorbates on NaX, and it was consistent with the values of micropore volume obtained by the structure analysing.This futher indicated the theory of micropore volume filling is applicable to the researched adsorption systems.The amount of limiting adsorption α_0, the variety of differential heat q with different temperature at a given filling value were calculated.The results in this paper are helpful for the design and manufacture of the solid adsorbent cooling system.