Efficient use of energy for cooling applications is a very important and challenging field in science. Ultra-low temperature actuated ( T driving < 80 °C) adsorption-driven chillers (ADCs) with water as the cooling agent are one environmentally benign option. The nanoscale metal-organic framework [Al(OH)(C 6 H 2 O 4 S)] denoted CAU-23 was discovered that possess favorable properties, including water adsorption capacity of 0.37 g H2O / g sorbent around p / p 0 = 0.3 and cycling stability of at least 5000 cycles. Most importantly the material has a driving temperature down to 60 °C, which allows for the exploitation of yet mostly unused temperature sources and a more efficient use of energy. These exceptional properties are due to its unique crystal structure, which was unequivocally elucidated by single crystal electron diffraction. Monte Carlo simulations were performed to reveal the water adsorption mechanism at the atomic level. With its green synthesis, CAU-23 is an ideal material to realize ultra-low temperature driven ADC devices.
The demand for cooling devices has increased during the last years and this trend will continue. Adsorption-driven chillers (ADCs) using water as the working fluid and low temperature waste energy for regeneration are an environmentally friendly alternative to currently employed cooling devices and can concurrently help to dramatically decrease energy consumption. Due to the ideal water sorption behavior and proven lifetime stability of [Al(OH)(m-BDC)] ∙ x H O (m-BDC = 1,3-benzenedicarboxylate), also denoted CAU-10-H, a green very robust synthesis process under reflux, with high yields up to 95% is developed and scaled up to 12 kg-scale. Shaping of the adsorbent is demonstrated, which is important for an application. Thus monoliths and coatings of CAU-10-H are produced using a water-based binder. The composites are thoroughly characterized toward their mechanical stability and water sorption behavior. Finally a full-scale heat exchanger is coated and tested under ADC working conditions. Fast adsorption dynamic leads to a high power output and a good power density. A low regeneration temperature of only 70 °C is demonstrated, allowing the use of low temperature sources like waste heat and solar thermal collectors.
The porous metal-organic framework (MOF) MIL-160 [Al(OH)(O 2 C-C 4 H 2 O-CO 2 )] was investigated by means of highresolution powder X-ray diffraction experiments using synchrotron radiation. The structures of the dehydrated, hydrated and nitrogen loaded forms of MIL-160 are refined by the Rietveld method. The structure of the hydrated form, as postulated from solid state NMR and DFT calculations, is confirmed. The hostguest and thermal responses of this compound are also investigated. Adsorption of water is found to induce a phase transition from I4 1 /amd (the dehydrated structure) to I4 1 md (the hydrated [a] Figure 8. Comparison of experimental (in red) and DFT (in blue) derived geometries of anhydrous 1 (top) and hydrated 1·4H 2 O (bottom), confirming the accuracy of the refined crystal structures.
This manuscript reports the Knoevenagel condensation reaction between benzaldehyde and malononitrile using CAU-1-NH2 as a reusable heterogeneous catalyst under mild reaction conditions.
The report is the first broader evaluation of the gas sorption properties of CAU-23 for the adsorptives CO 2 , H 2 , CH 4 , and SO 2 . CAU-23 is of intermediate porosity among Al-MOFs with specific BET surface areas of the order of MIL-100 > MIL-53 > CAU-23 > MIL-160 > MIL-53-TDC > Alfum > CAU-10-H and total pore volumes of the order of MIL-100 > MIL-53 > CAU-23 > Alfum = MIL-160 > MIL-53-TDC > CAU-10-H. CO 2 uptake (3.97 mmol g À 1 , 293 K) and H 2 uptake (10.25 mmol g À 1 , 77 K) of CAU-23 are second in the series and only slightly smaller than for MIL-160. The CH 4 uptake of CAU-23 (0.89 mmol g À 1 , 293 K) is unremarkable in comparison with the other Al-MOFs. The SO 2 uptake (8.4 mmol g À 1 , 293 K) follows the porosity and higher SO 2 uptakes were only observed for MIL-53 and MIL-100. CAU-23 is one of the best Al-MOFs for high-pressure sorption of CO 2 , with an uptake of 33 wt.-% at 20 bar, 293 K. Gas sorption measurements at two different temperatures gave near zero-coverage enthalpy of adsorptions, ~Hads 0 for CO 2 of À 22 kJ mol À 1 and of SO 2 for À 38 kJ mol À 1 which is at the low end of the other Al-MOFs (À 22 to À 39 kJ mol À 1 for CO 2 ; À 41 to À 51 kJ mol À 1 for SO 2 ), yet ~Hads increases for CAU-23 with CO 2 and SO 2 to À 25 and À 57 kJ mol À 1 , respectively. For CO 2 /CH 4 and SO 2 /CO 2 separation, ideal adsorbed solution theory (IAST) predicted gas selectivities of 5 and 27-50 (depending on molar ratio and model), respectively, in line with 4.5-6.3 and 17-50, respectively, with most of the other Al-MOFs, where only MIL-53-TDC with 83 and MIL-160 with 126 gave a higher SO 2 /CO 2 selectivity at a molar ratio of 0.5.
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