Ammonia sorption on the composites “(BaCl2 + BaBr2) inside vermiculite pores”

This paper presents the data on the phase composition and ammonia sorption equilibrium of the new composite sorbents “(BaCl2 + BaBr2) inside vermiculite pores” intently prepared for adsorptive cooling. Phase transformation of the composites during ammonia sorption was characterized by in situ X-ray diffraction. The isotherms of ammonia sorption on the composites were measured in the ammonia pressure range P = 0–10 bar at temperatures T = 303–343 K. The formation of the salts solid solution BaClxBr2−x inside the vermiculite pores was observed. Due to the ammonia sorption this solution transformed to the complex BaClxBr2−x·8NH3, which formation was observed at intermediate ammonia pressure between those for the single salts BaCl2 and BaBr2. The isosteric enthalpy ΔH of ammonia sorption on the composites with molar ratio BaCl2/BaBr2 3:2 and 1:1.2 equals (−35 ± 3) kJ/mol and does not depend on the ammonia uptake. The isosteric entropy ΔS changes from (−115 ± 2) to (−133 ± 2) J/(mol K) with the increase in the ammonia sorption from 1 to 7 mol NH3/mol salt.