High Temperature and Pressure Pure-Silica Zeolite Ammonia Adsorbents and Their Use in Pressure Swing Adsorption Separations

Separating ammonia from the reactor effluent remains a major energy bottleneck in industrial synthesis processes, where cryogenic condensation is typically employed. This method is energy-intensive, and alternative approaches such as pressure swing adsorption have not been widely adopted due to challenges associated with ammonia’s high affinity for adsorbents and the difficulty of complete regeneration under practical conditions. Here, we introduce pure- silica zeolites for this application. We determine first the high-pressure high-temperature adsorption data using a specially designed adsorption equipment. Our findings indicate that pure-silica zeolites exhibit high ammonia working adsorption capacity compared to previously reported commercial adsorbents. Molecular simulations provide information on adsorbate distribution and explain observed trends in adsorbed amounts and enthalpies. A 4-column 4- step pressure and temperature swing adsorption is designed and modeled at process relevant conditions, achieving ammonia purity above 99 % and recovery over 98 %, demonstrating the potential of replacing the energy intensive cryogenic separation.