(532bg) Catalytic Descriptors for Selective Methane Chlorination through Electrophilic Pathway

Methane is a simple hydrocarbon that is a component of natural gas, which can be used as the direct fuel source. However, due to the high C–H bond stability, methane utilization remains at a low level. Methane chlorination is considered one of the methane utilization methods to activate the C–H bond, from which the chlrolomethanes can be produced as the valuable materials that can also be used as the platform chemicals to be converted to light olefins. Among the possible products (e.g., CH₃Cl, CH₂Cl₂, CHCl₃, and CCl₄), methyl chloride (CH₃Cl) is important because CH₃Cl is intermediate for producing light olefins with coupling reactions. However, selective CH₃Cl production is challenging because two pathways can occur competitively during the reaction. One is the radical pathway, and the other is the electrophilic pathway. The former is the dominant pathway, which produces chlorine radicals that accelerate uncontrollable polychlorination to undesired polychlorinated products. Therefore, for achieving a high selectivity of CH₃Cl, the electrophilic pathway needs to be dominant.

Herein, we confirmed experimentally that various transition metals in zeolites can control the methane conversion and CH₃Cl selectivity. Among the various metal ion-exchanged zeolites, some transition metal ions showed high CH₃Cl selectivity which seems the electrophilic pathway is dominant. We also found that DFT calculations can explain the tendencies of methane conversion and CH₃Cl selectivity depending on the type of metal ions in zeolites. Detailed interpretation is going to be demonstrated in the poster.