Examining the Ethane Selective Potential of MOFs for Ethylene Purification*

Ethylene plays an important role in the petrochemical industry, however cryogenic separation—the most popular method for purifying ethylene—is also one of the most expensive and energy intensive processes in the chemical industry. Therefore, alternative cost-effective technologies to efficiently purify ethylene at ambient conditions are of paramount interest. Highly porous metal organic frameworks (MOFs) have emerged as promising materials for the task of gas separation due to their highly tunable nature. However, one major issue is their ethylene-selective separation which leads to the need for a desorption process to obtain the desired ethylene. Consequently, ethane selective MOFs are of significant interest due to potential savings of time and energy. Here we combine ab initio calculations with dynamic sorption experiments to examine the effectiveness of pore geometry tuning in synthesizing ethane selective MOFs. The main focus of the study is on MOF-801 with UiO-66 being used for comparison as it selects for ethane and shares the same metal cluster structure. MOF-801 shows a noticeable enhancement in selectivity of ethane when compared to UiO-66 due to the different pore geometry. This improved selectivity leads to polymer grade ethylene of over 99.9% purity. The experiments also show that MOF-801 is quite robust as it maintains its stability in the presence of various solutions, and that the MOF also has strong structural integrity giving it great recyclability.