Calcium/strontium chloride impregnated zeolite A and X granules as optimized ammonia sorbents

Calcium chloride (CaCl(2)) impregnated zeolite A and strontium chloride (SrCl(2)) impregnated zeolite A and X composite granules were evaluated as ammonia sorbents for automotive selective catalytic reduction systems. The SrCl(2)-impregnated zeolite A granules showed a 14% increase in ammonia uptake capacity (8.39 mmol g(−1)) compared to zeolite A granules (7.38 mmol g(−1)). Furthermore, composite granules showed 243% faster kinetics of ammonia sorption (0.24 mmol g(−1) min(−1)) compared to SrCl(2) (0.07 mmol g(−1) min(−1)) in the first 20 min. The composite CaCl(2)/SrCl(2) impregnated zeolite A granules combined the advantages of the zeolites and CaCl(2)/SrCl(2), where the rapid physisorption from zeolites can reduce the ammonia loading and release time, and chemisorption from the CaCl(2)/SrCl(2) offers abundant ammonia capacity. Moreover, by optimizing the content of SrCl(2) loading, the composite granules maintained the granular form with a crushing load of 17 N per granule after ammonia sorption–desorption cycles. Such structurally stable composite sorbents offer an opportunity for fast ammonia loading/release in automotive selective catalytic reduction systems.