Recyclable ammonia uptake of CuCl2/graphite composite adsorbents with high adsorption capacity

Abstract

Ammonia is considered a good hydrogen storage material due to its advantages of high hydrogen content density. At the same time, the characteristic of efficient heat transfer of ammonia makes it develop rapidly in many energy industries. However, unutilized NH3 can cause corrosion and poisoning, therefore, NH3 must be captured in time. Metal chloride is a green, efficient and sustainably utilized material for NH3 adsorption and capture. In this paper, a novel composite adsorbent was proposed by loading graphite to CuCl2 to enhance the NH3 adsorption·NH3 adsorption–desorption experiments of composite adsorbents were performed on the fixed bed. The results showed that the optimal loading of graphite on CuCl2 was 20 wt% and the optimal adsorption temperature was 25 ℃. The optimal adsorption of CuCl2-G (20) was 0.64 g NH3/g adsorbent. Moreover, the composite adsorbents showed good stability in NH3 adsorption properties during long-term cycling. The cumulative NH3 adsorption capacity of CuCl2-G (20) in the 10 cycles was up to 5.8 g NH3/g adsorbent, which was 0.07 g NH3/g adsorbent higher than that of CuCl2. Notably, all graphite-loaded composite adsorbents showed a stronger NH3 adsorption capacity than a single CuCl2 in the 2nd and subsequent cycles. Thus, CuCl2-G (20) is a promising adsorbent with potential application in the removal and enrichment of excess NH3 produced in industrial processes.