Influence of MIL‐101 Doping by Ionic Clusters on Hydrogen Storage Performance up to 1900 Bar

Abstract

Ultra-high-pressure hydrogen-storage performance (up to 1900 bar) was investigated for mesoporous chromium terephthalate MIL-101 and its inclusion compounds containing ionic clusters [Re(4)S(4)F(12)](4-) and [SiW(11)O(39)](7-) within the porous framework. The maximum specific hydrogen uptake values (total) for MIL-101 are 12.3 (at 81) and 7.2 wt. % (at 293 K). Such unique measurement conditions allowed us to identify the density of the absorbed hydrogen directly from the excess sorption isotherm curves. The corresponding density values were found to be almost comparable at low temperature, but significantly different at ambient temperature, which indicated an increase of more than double in the number of hydrogen binding sites in the case of the inclusion compounds with rhenium clusters.

High-pressure hydrogen storage on modified MIL-101 metal-organic framework

“…We have to note that the adsorption-desorption process is completely reversible with negligible hysteresis. A similar effect was observed and discussed for MIL-101 doped by ionic clusters [12]. The H 2 uptake at 81 K and pressures of about 30 bar for both MIL-101 + Pt/C composites is lower compared with that of the pristine material.…”

“…Meanwhile, the excess adsorption on microporous materials refers to a surface adsorption surplus compared with the compressed gas in the same volume and, therefore, is more a practical and reasonable parameter for CGH2 systems. The appearance of such 'zero point', which does not exist on conventional Langmuir-type isotherms, has been theoretically predicted and later observed experimentally [11,12]. At a particular very high pressure, the excess adsorption isotherm line should eventually cross the pressure axis and continue to negative values.…”

“…Hydrogen adsorption and desorption isotherms were measured for 1 g of samples by a volumetric method on a Sieverts-type experimental unit specifically designed for studies of solid-gas reactions under pressures up to 2000 bar [12,30]. A metal hydride store was used as a source of high-purity hydrogen (99.9999%).…”

“…Our previous results related to mesoporous chromium(III) terephthalate MIL-101 ('MIL' = Materials of Institute Lavoisier) [28] had shown that the pristine compound is not applicable for hydrogen storage above 150 bar as the excess adsorption became negative [12]. Our previous results related to mesoporous chromium(III) terephthalate MIL-101 ('MIL' = Materials of Institute Lavoisier) [28] had shown that the pristine compound is not applicable for hydrogen storage above 150 bar as the excess adsorption became negative [12].…”

Adsorptive characterization of porous solids: Error analysis guides the way

“…These materials have found application in adsorptive separation [5][6][7], storage [8], encapsulation [9] and catalysis [10]. MIL-101(Cr) [11] is among the most famous structures, it contains both meso-and micropores, and displays high stability and interesting properties [12][13][14][15][16][17]. Second MOF is the fully microporous UiO-66 [18], which also gained significant attention because of excellent stability and interesting properties [19][20][21][22].…”