NH₃ Adsorption Performance of Silicon-Supported Metal Chlorides

Alkaline earth metal chlorides (AEMH) are considered to be the key to effectively solving the problem of NH3 storage due to their ability to react with NH3 to form stable ammonia complexes. This study attempted to investigate the NH3 adsorption performance of four metal chlorides (CuCl2, MnCl2, MgCl2, and CaCl2) and silicon-supported composite adsorbents with a fixed bed. The adsorbents were characterized by X-ray diffraction, Brunauer–Emmett–Teller, and scanning electron microscopy to analyze the NH3 adsorption behavior. The experiment found that the NH3 adsorption capacity of four metal chlorides is in order: CuCl2 > MnCl2 > MgCl2 > CaCl2, and the adsorption capacity of metal chlorides decreased with the increase in temperature. In addition, the composite adsorbents of silicon-supported metal chlorides were synthesized by the wet impregnation method. Ammonia adsorption experiments showed that silicon can significantly improve the NH3 adsorption capacity of metal chlorides, and the NH3 adsorption capacity of MnCl2/silicon was 127.5% higher than that of MnCl2. Silicon played the role of the skeleton support in the metal chloride particles, hindering the agglomeration between particles and increasing the number of pores on the surface of the particles, which was conducive to the diffusion of NH3 through the pores into the particles for adsorption.