Hydrothermal Green Synthesis of a Robust Al Metal-Organic-Framework Effective for Water Adsorption Heat Allocations

To
minimize the huge global energy consumption for cooling and
heating, adsorption-based heat allocation devices operating with an
“adsorbent–water” working pair have received
great interest over the last decades. Herein, we report scalable green
synthesis of an Al-based metal–organic framework (Al-MOF) in
water built from the assembly of inorganic Al helix chains linked
to pyridine dicarboxylate linkers that delimits a three-dimensional
structure proven to be isoreticular to CAU-10H and denoted as CAU-10pydc.
This channel-like MOF exhibits attractive water sorption properties
with an S-shaped adsorption isotherm associated with a major water
uptake in the range of P/P°
= 0.015–0.17 and a good working capacity (0.31 mLH2O mL–1MOF) under low-temperature cooling
conditions of the adsorption-driven heat allocation system (Tevaporator(ev) = 5 °C, Tadsorption(ads) and Tcondensation(con) = 30 °C, and Tdesorption(des) =
80 °C), along with exceptional coefficient of performances for
both cooling (0.79) and heating (1.72) together with a useful and
sustainable heat source accessible from a solar source and good specific
heat capacity (212.9 kWh m–3MOF) and
heat storage capacity (273.5 kWh m–3MOF). The molecular adsorption mechanism was finally investigated computationally
demonstrating the predominant role played by the formation of hydrogen-bonding
between water molecules and the hydroxyl functionality of the MOF.