System-level analysis for continuous BTX production from shale gas over Mo/HZSM-5 catalyst: Promotion effects of CO2 co-feeding on process economics and environment

초록

Benzene, toluene, and xylene (BTX) production from shale-derived CH4, C2H6, and C3H8 is considered an energy-efficient technology substituting their naphtha-cracking counterparts. However, the economics of BTX production from shale gas remains questionable because of the rapid deactivation of the catalyst, originating from the coke generation. Herein, we present a BTX production strategy with CO2 co-feeding for catalyst stability enhancement and additional H-2 production. Our process prevents coke deposition on the active sites of Mo and zeolite, and improves the operation time of reactors compared to that of shale gas without CO2 co-feeding. Concurrently, H-2 and CO are produced with BTX owing to the dry reforming reaction of hydrocarbons over the Mo/HZSM-5 catalyst. Most importantly, the economics of BTX production with CO2 co-feeding is evaluated using individual system components integrated with two different CH4 conversion processes (steam-reforming-based H-2 and methanol production). The BTX production with CO2 co-feeding lowers the methanol production cost by additionally producing methanol generated by CO from the BTX reactor, while the H-2 production cost increases. Moreover, the life cycle assessment proves that the CO2 emission during the methanol production process is significantly reduced by recycling the CO2 produced in the subsequent process.

키워드