Investigation for energy state of zeolites

成功地进行了沸石-水热泵的循环运行，阐明了沸石中的水分子，沸石水作为一个独立的组成部分，具有非常大的热容，几乎是具有最大比热容的材料纯水的两倍。沸石水从25℃加热到100℃时的焓增为10.6kJ / mol H_2O，而纯水的焓增为5.25kJ / mol H_2O。计算是基于沸石在加热过程中不脱水的理想情况下进行的，因为沸石在25℃与水的蒸汽压平衡下，加热到100℃时，沸石的脱水率为3-4%。由于Mg53-A沸石在不同水化水平下的水化焓值相对恒定为-65kJ/mol，因此该值几乎等于微分焓。这证明了沸石空隙中沸石水的大热容反映了沸石水的性质，即沸石水在那里发生了剧烈的能量变化。事实支持沸石-水热泵系统的独特功能，有效地利用低温热源。通过平衡蒸汽压-温关系实验，证明了沸石水的低熵性。采用x射线单晶结构分析方法，对原始和脱水样品进行了晶体结构分析和水分子位置分析。

Cyclic operation of a zeolite-water heat pump has been done successfully, and clarified that water molecule in zeolite, zeolitic water, as an independent component has very large heat capacity as much as almost twice of that of pure water which has the largest specific heat capacity of materials. Enthalpy increment of zeolitic water by heating from 25℃ to 100℃ was 10.6kJ per one mole of H_2O, whereas that of pure water is 5.25kJ. The calculation was done based on an ideal case without dehydration of zeolite during heating, as the real heating accompanies dehydration by 3-4% up to 100℃, when the zeolite is under the vapor pressure equilibrated with water at 25℃. As the enthalpy values of hydration is rater constant to be -65kJ/mol for various hydration levels of Mg53-A zeolite, the value is thought to be almost equal to the differential enthalpy. This proves that the large heat capacity reflects the nature of the zeolitic water in the void of the zeolite, that is, drastic- energetic change of zeolitic water there. The fact supports the unique function of the zeolite-water heat pump system for effective use of low temperature heat sources. The low entropy of zeolitic water was proved also by the experiment of equilibrium vapor pressure-temperature relations. Crystal structures of chabazite as well as the sites of water molecule were analyzed by X-ray single crystal structure analyses of both the raw chabazite and the dehydrated sample.