Porous composite materials are potential candidates for water-based adsorptive heat transformation (AHT) applications. Here, a solid adsorbent LiCl@UiO-66 as a 'composite salt inside porous matrix’ (CSPM) has been prepared by incorporating hygroscopic lithium chloride into a microporous metal–organic framework (MOF) UiO-66 as a host matrix through the wet impregnation method. In our wet impregnation we did not let the excess salt solution dry to prevent salt precipitation on the matrix surface. This yielded a true salt@MOF composite with no deliquescence of LiCl and strongly enhanced the water adsorption capacity of UiO-66 through the salt content. At p/p₀ = 0.1 the water vapor sorption isotherms show a hydration state of LiCl inside the MOF of LiCl·2–4H₂O which is much higher than for neat LiCl with 0.5H₂O, due to the dispersion of a small particle size inside the matrix. LiCl@UiO-66 with a 30 wt% LiCl content (LiCl@UiO-66_30) has a 3 to 8 times higher water uptake over neat UiO-66 (depending on relative pressure) and could reach a volumetric and gravimetric water uptake of over 2.15 g g⁻¹ at p/p₀ = 0.9, which outperforms the so far known UiO-66-based composites. Cycling tests confirmed the hydrothermal stability of the LiCl@UiO-66 composites. Kinetic evaluation of the gravimetric water uptake (at 90% relative humidity) over time yielded rate coefficients up to 2.0(1) × 10⁻⁴ s⁻¹ which is slower than that in neat UiO-66 (6.7(6) × 10⁻⁴ s⁻¹) but faster than that for salt@silica gel composites. The coefficient of performance for the heat pumping mode (at T_des/T_ads/T_evap set to 90/40/10 °C) of 1.64 for LiCl@UiO-66_30 exceeds those of other MOFs, salt@MOF or salt@silica gel composites. For thermal battery applications the heat storage capacity (C_HS) for LiCl@UiO-66_30 is 900 kJ kg⁻¹ (=0.25 kW h kg⁻¹), which can reach the Department of Energy (DOE) value of 2.5 kW h/35 kg with just 10 kg of material and outperforms CaCl₂@UiO-66_38 with a C_HS value of 367 kJ kg⁻¹.

中文翻译：

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可调节的LiCl @ UiO-66复合材料，用于基于水吸收的热转化应用

多孔复合材料是水基吸附热转化（AHT）应用的潜在候选材料。在这里，通过将吸湿性氯化锂通过湿法掺入作为主体基质的微孔金属-有机骨架（MOF）UiO-66中，制备了作为“多孔基质中的复合盐”的固体吸附剂LiCl @ UiO-66。浸渍方法。在湿法浸渍中，我们没有让过量的盐溶液干燥以防止盐在基质表面上沉淀。这样制得的是真正的Salt @ MOF复合材料，没有LiCl的潮解作用，并且通过含盐量大大增强了UiO-66的吸水能力。在p / p ₀ = 0.1时，水蒸气吸附等温线显示LiCl·2-4H ₂ MOF内LiCl的水合状态由于基体内有小粒径的分散，O比含0.5H ₂ O的纯LiCl高得多。LiCl含量为30 wt％的LiCl @ UiO-66（LiCl @ UiO-66_30）的吸水量是纯UiO-66的3至8倍（取决于相对压力），体积和重量吸水量可超过纯UiO-66。在p / p ₀ = 0.9时为2.15 gg ^-1，优于目前已知的基于UiO-66的复合材料。循环测试证实了LiCl @ UiO-66复合材料的水热稳定性。重量吸水量（相对湿度为90％）随时间的动力学评估得出速率系数高达2.0（1）×10 ^-4 s ^-1比纯UiO-66（6.7（6）×10 ^-4 s ^-1）慢，但比盐@硅胶复合材料快。的表现为热泵送模式（在系数Ť _DES / Ť_广告/ Ť _EVAP至90/40/10集℃）的1.64的LiCl @ UIO-66_30超过那些其他的MOF，盐@ MOF或盐@二氧化硅凝胶复合材料。对于热电池应用，LiCl @ UiO-66_30的储热容量（C _HS）为900 kJ kg ^-1（= 0.25 kW h kg ^-1），可以达到能源部（DOE）的2.5 kW h / 35公斤（仅10公斤物料），性能优于CaCl ₂@ UiO-66_38，其C _HS值为367 kJ kg ^-1。