In addition, the catalytic stability of ethylene/toluene and CO2/H2/toluene systems were compared (Fig. ). In the ethylene/ toluene catalytic system, after the activation period around 6 hours, the conversion of ethylene could only remain stable for 32 hours and the obvious deactivation occurred after 40 hours. While in the CO2/H2/toluene catalytic system, it could run continuously for more than 100 hours without any deactivation observed. TG was employed to quantify the amount of coke formed over zeolites during reaction.