(260d) The Effect of Aluminum Ordering on Carbon Dioxide Adsorption in Zeolites

The distribution of Al in cationic zeolites is important in controlling the performance of these materials for catalysis and separations. However, it is difficult to measure this distribution experimentally. In this work, we examine the effect of Al distribution on CO₂ adsorption in seven industrially-relevant zeolite topologies using molecular simulations based on DFT/CC-derived force fields. A Reverse Monte Carlo method is used to generate Al distributions with varying degrees of order or randomness. Grand Canonical Monte Carlo simulations for Na⁺-exchanged zeolites indicate that CO₂ adsorption isotherms can be used to distinguish between Al distributions. These simulation results agree with experimental results in the limited number of cases where information is independently available about Al ordering. Differences in CO₂ adsorption isotherms can be understood in terms of the existence of dual and single cation adsorption sites. Our results indicate that CO₂ adsorption measurements combined with GCMC simulations can be used to determine the Al distribution in zeolites without relying on more challenging experimental techniques.