One Step Acetic Acid Formation Through Simultaneous Activation of Methane and Co2 over Cu Exchanged Zsm-5 CatalystsAuthor(s): Jingying Pan
The ultimate goal of our study is the development of strategies to exploit methane and carbon dioxide resources more efficiently and cleanly. Due to the high stabilities of both methane and CO2, simultaneous C-H bond activation of methane and CO2 is the one of the toughest challenge in catalysis. Formation of acetic acid was achieved by the concurrent feed of methane and carbon dioxide over Cu loaded basic cation ZSM-5 catalysts under the continuous flow microreactor system. The formation of acetic acid was observed in the broad temperature range of 425°C to 525°C with a co-feed unimolar ratio of CO2/CH4, under low space velocity of 360 ml hr-1 based on methane. The formation rate of acetic acid was observed to be low in Cu°-H-ZSM-5, however, the cation exchanged M+-ZSM-5 catalyst showed remarkable increment in the formation rate of acetic acid. The basic cations showed the catalytic activity in the following order K>Na>Ca>Li. This indicates that basic cations helps in providing surface active CO2 in the form of carbonates, which led to efficient CO2 insertion into activated C-H bond from methane over reduced Cu metallic nanoparticles. The bi-functional Cu and basic cationic species, together ascribes to the outstanding formation rates of acetic acid. The Cu0-K-ZSM-5 catalyst exhibited the highest formation rate of acetic acid of 12424 μ mole gcat-1h-1 at the initial activity and 395 μ mole gcat-1h-1 at steady state, for 10 h time-on-stream at 500°C.