Department of Physics, Umeå University, S-90187, Umeå, Sweden.
Phys Chem Chem Phys. 2018 Nov 14;20(44):27983-27991. doi: 10.1039/c8cp05241g.
The most common methods to evaluate hydrogen sorption (volumetric and gravimetric) require significant experience and expensive equipment for providing reproducible results. Both methods allow one to measure excess uptake values which are used to calculate the total amount of hydrogen stored inside of a tank as required for applications. Here we propose an easy to use and inexpensive alternative approach which allows one to evaluate directly the weight of hydrogen inside a material-filled test tank. The weight of the same tank filled with compressed hydrogen in the absence of loaded material is used as a reference. We argue that the only parameter which is of importance for hydrogen storage applications is by how much the material improves the total weight of hydrogen inside of the given volume compared to compressed gas. This parameter which we propose to name Gain includes both volumetric and gravimetric characterization of the material; it can be determined directly without knowing the skeletal volume of the material or excess sorption. The feasibility of the Gravimetric Tank (GT) method was tested using several common carbon and Metal Organic Framework (MOF) materials. The best Gain value of ∼12% was found for the Cu-BTC MOF which means that the tank completely filled with this material stores a 12% higher amount of hydrogen compared to H2 gas at the same P-T conditions. The advantages of the GT method are its inexpensive design, extremely simple procedures and direct results in terms of tank capacity as required for industrial applications. The GT method could be proposed as a standard check for verification of the high hydrogen storage capacity of new materials. The GT method is expected to provide even better accuracy for evaluation of a material's performance for storage of denser gases like e.g. CO2 and CH4.
评估氢气吸附（体积和重量）最常用的方法需要丰富的经验和昂贵的设备来提供可重复的结果。这两种方法都可以测量过剩的吸收值，这些值用于计算储存在储氢罐中的氢气总量，这是应用所需要的。在这里，我们提出了一种简单易用且经济实惠的替代方法，可以直接评估填充材料的测试罐中氢气的重量。装满压缩氢气的相同罐体的重量（无负载材料）用作参考。我们认为，对于氢气存储应用，唯一重要的参数是材料相对于压缩气体在给定体积内增加了多少氢气的总重量。我们建议将这个参数命名为增益（Gain），它包括了材料的体积和重量特性；它可以直接确定，而无需知道材料的骨架体积或过剩吸附。使用几种常见的碳和金属有机骨架（MOF）材料测试了重量储氢罐（Gravimetric Tank，GT）方法的可行性。Cu-BTC MOF 的最佳增益值为 ∼12%，这意味着完全填充这种材料的罐体在相同的 P-T 条件下储存的氢气量比 H2 气体高 12%。GT 方法的优点是其设计经济实惠，程序极其简单，并且可以直接获得工业应用所需的罐体容量等结果。GT 方法可以作为验证新材料高储氢能力的标准检查方法。GT 方法有望为评估更密集气体（例如 CO2 和 CH4）存储性能的材料提供更好的准确性。
