Scalable Green Synthesis and Full‐Scale Test of the Metal–Organic Framework CAU‐10‐H for Use in Adsorption‐Driven Chillers

Abstract

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.

Solvent Impact on the Properties of Benchmark Metal–Organic Frameworks: Acetonitrile‐Based Synthesis of CAU‐10, Ce‐UiO‐66, and Al‐MIL‐53

“…Water adsorption experiments (Figure ) show that the synthesized CAU‐10 exhibits properties similar to those previously reported for this material with a steep increase at p/p°=0.2 . For Ce‐UiO‐66 a one‐step water adsorption (250 mg g −1 ) between p/p° values of 0.25 and 0.5 is observed, which matches data from conventionally synthesized Ce‐UiO‐66 (Figure S21).…”

“…In some selected cases, water has already been used as an alternative solvent, considering for example the synthesis of −COOH‐functionalized Zr‐UiO‐66, Al‐MIL‐53, or CAU‐10 . Nonetheless, water‐based routes are often either limited to very polar organic linker molecules or require high temperatures to realize sufficient dissolution of less polar reactants.…”

“…As a typical illustration, an acetonitrile‐based synthetic strategy was applied by using different metal ions and linker molecules (Table S2). On the basis of our previous work on Al‐ and Ce‐MOFs, the following three compounds were chosen for a more detailed study: 1) CAU‐10 [Al(OH)(ISO)] is an aluminum MOF, well‐known for its applicability in adsorption‐driven chilling (ISO 2− : isophthalate) . It exhibits infinite helical chains of cis corner‐sharing AlO 6 polyhedra, which are interconnected by V‐shaped isophthalate ions to form a three‐dimensional network with square‐shaped, sinusoidal pore channels (Figure , top left) .…”

“…Here, we present the syntheses of CAU‐10, Ce‐UiO‐66, and Al‐MIL‐53 from acetonitrile as well as the characterization of the products with a special focus on changes of the framework flexibility of Al‐MIL‐53.…”

Overcoming Crystallinity Limitations of Aluminium Metal‐Organic Frameworks by Oxalic Acid Modulated Synthesis

“…In this regard, Al‐MOFs are of special interest as they combine high operating temperatures, convenient syntheses in aqueous media, and high natural abundance of the metal sources. Moreover, their exceptional chemical stability in both aqueous and organic media makes this class of materials ideal for applications that are unsuitable for most MOFs, such as moisture harvesting, adsorption‐driven heat exchange, and water remediation . Unfortunately, the synthesis of highly crystalline Al‐MOFs is a long‐standing challenge as most of these can only be obtained as nanocrystalline powders and such limitations are known to have detrimental effects on MOFs’ porosity and sorption capacity .…”