Modification of Active Carbon and Expanded Graphite on SrCl ₂ for Ammonia Adsorption in Solid Selective Catalytic Reduction

ABSTRACT Solid selective catalytic reduction (SCR) is a promising nitrogen oxides abatement technology with advantages over urea‐SCR, such as higher ammonia storage density, no low‐temperature crystallization, and no exhaust temperature limitation. However, conventional metal chloride adsorbents for solid SCR (SSCR) suffer from two critical issues: ammonia adsorption decay after repeated cycles and poor thermal conductivity, which restrict their practical application. To address these problems, this study aimed to prepare strontium chloride (SrCl 2 )/active carbon and SrCl 2 /expanded graphite (EG) for SSCR systems and systematically investigate their ammonia adsorption characteristics and key influencing factors. The principal findings are as follows: the optimal mass ratio of SrCl 2 to active carbon/EG was 5:1/6:1, respectively, with the optimal expansion ratio of EG being approximately 148 times, which ensures high initial ammonia adsorption capacity and no adsorption decay during multiple adsorption‐desorption cycles. A comparative analysis further showed that the SrCl 2 /EG adsorber exhibited higher ammonia bulk density, higher ammonia mass density, and better thermal conductivity than SrCl 2 /active carbon. In conclusion, SrCl 2 /EG is the optimal composite adsorber for SSCR systems, as its excellent thermal conductivity can enhance the material's heating rate and thereby shorten the ammonia start‐up time.