Heteroepitaxial growth of DDR zeolite membranes for pervaporation dehydration of hypersaline LiBr solutions

LiBr-H₂O absorption chillers offer significant advantages in cooling applications; however, their widespread implementation has been severely limited by their large weight and size. The miniaturization of their key components is therefore critical to expanding their practical applications. This study presents a novel desorber design that employs a pervaporation process to concentrate LiBr solutions using DDR zeolite membranes. High-quality DDR zeolite membranes were fabricated via a heteroepitaxial growth process, utilizing CHA rather than DDR zeolite seeds, owing to the successful suppression of the SGT competitive phase during membrane synthesis. The resulting DDR zeolite membrane exhibited a water flux ranging from 0.16 to 1.56 kg·m −2 ·h −1 and a LiBr rejection exceeding 99.9 % for 20–60 wt% LiBr solutions at temperatures of 20–80 °C. The activation energy for water permeation decreased from 20.64 to 9.69 kJ·mol −1 as the LiBr concentration increased from 20 to 60 wt%, which stemmed primarily from the combined effect of the thermodynamic properties of LiBr solutions and the adsorption behaviors of the membrane. Moreover, the DDR zeolite membrane demonstrated excellent stability in the pervaporation dehydration of LiBr solutions, even at 80 °C, highlighting its potential for use in desorbers for LiBr-H₂O absorption chillers.