XCl2/MWCNTs─Composites Based on Multi-Walled Carbon Nanotubes and Metal Chlorides for NH3 Capture and Separation

With the development of ammonia (NH3) synthesis technology from biomass in recent years, safe and efficient ammonia capture and separation technology have become one of the key problems that need to be solved urgently. In this paper, composite adsorbents of four metal chlorides (CuCl2, MnCl2, MgCl2, and CaCl2) and multi-walled carbon nanotubes (MWCNTs) were prepared by the wet impregnation method to improve the NH3 adsorption capacity of MWCNTs. The NH3 adsorption and desorption experiments of the composite adsorbents were carried out on a fixed-bed reactor. The results showed that the chemisorption of NH3 by metal chlorides was the main factor to improve the NH3 adsorption capacity. Among the four composite adsorbents, CuCl2/MWCNTs had not only the highest NH3 adsorption capacity (0.69 g NH3/g adsorbent, 7.5 times the NH3 adsorption capacity of MWCNTs) but also the highest NH3 desorption rate, which is a highly promising NH3 storage material.