Using the gravimetric method the adsorption characteristics of SAPO-34 zeolite and silica gel to water vapor in vacuum condition have been experimentally studied. Comparisons of the result in vacuum condition to the result in moist air condition were carefully conducted. It was found that the equilibrium adsorption concentration of the two materials in vacuum condition was higher than the equilibrium concentration in moist air under the same condition. Also, the adsorption time to reach the equilibrium state was greatly shortened in vacuum cases. The maximum time shortening was up to 48.1% for the SAPO-34 zeolite and 38.8% for the silica gel as compared to the time of the moist air cases. With an anti-S type of the adsorption isotherm curve the concentration change of the SAPO-34 zeolite was insensitive in the middle pressure range, while the concentration change of the silica gel was more sensitive in the middle pressure range with a S type isotherm curve. The existing Freundlich equation and S-B-K equation did not fit well the adsorption isotherm of the SAPO-34 zeolite and the silica gel. Therefore novel correlations were proposed and they fitted the experimental data with much better accuracy.

中文翻译：

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真空条件下SAPO-34沸石和硅胶吸附特性的实验研究

用重量法对SAPO-34分子筛和硅胶在真空条件下对水蒸气的吸附特性进行了实验研究。仔细比较了真空条件下的结果和潮湿空气条件下的结果。发现在相同条件下，两种材料在真空条件下的平衡吸附浓度高于在潮湿空气中的平衡浓度。而且，在真空情况下，达到平衡状态的吸附时间大大缩短。与潮湿空气的时间相比，SAPO-34沸石的最大缩短时间高达48.1％，硅胶的最大缩短时间为38.8％。使用反S型吸附等温线曲线，SAPO-34沸石的浓度变化在中压范围内不敏感，硅胶的浓度变化在中等压力范围内具有S型等温线。现有的Freundlich方程和SBK方程不能很好地拟合SAPO-34沸石和硅胶的吸附等温线。因此提出了新颖的相关性，并且它们以更好的精度拟合了实验数据。