Study For The Catalysis And Activation Of Methane At Low Temperature

Some reactions including oxidative coupling of methane, aromatization of CH4, C2H4, C3H8, C4H10 and on the influence of CO2 were systemicly researched in this paper. The highly-active catalysts are studied and the result are listed below:The Li(SO42-, Cr)/MgO-(La2O3, Sm2O3) , Li/MnOx-(MgO, A12O3, Fe2O3), Na2W2O4-MnOx-LiCl-(TiO2, TS, SBA15) , MnO2/Li (SO42-, Cl-)- H3BO3, Li2SO4-Mnx0y/TiO2 catalysts for Oxidative Coupling of Methane (OCM) have been studied, and the results show the MnO2/Li(SO42-,Cr)-H3BO3, Li2SO4-MnxOy/TiO2 catalysts have high activity and selectivity. Furthermore, the influence of the components and the reactive conditions on the activity of catalysts has been studied and found the possible active new component, cubic Li4B7O12Cl.C1-C4 alkane or alkene aromatizations are mainly studied. The catalysts that used include there systemic catalysts: metal modified HZSM-5 zeolite catalysts that have single metal (Zn, Ga, Mo, Co and W etc), muti-metal (Zn-Ga, Gd-Zn, Cr-Mo, Al-Mo, Zn-Ni-Co and Cr-Mo-Zn etc) heteropoly acid salt (Cu1.5PW12O40 etc) modified zeolite catalysts; Zn-modified SBA-15 molecular sieve catalysts; Zn-modified Cr-Si molecular sieve catalysts. From the experiment results we find many delightful achievement:Ethylene aromatization is mainly studied on modified HZSM-5.The results is better that aromatics products yield exceed 70% over 2%Ga/HZSM-5, 1.35%Zn/HZSM-5, 0.5%La-1.35%Zn/HZSM-5, 1.35%Zn-l%Al/HZSM-5 and l%Cr-2%Mo-1.35%Zn/HZSM-5 catalysts. We also simply discuss the reaction pathway of ethylene over the bifunctional metal modified HZSM-5. The effect of temperature and molar ratio on propane or butane aromatization is also studied.The higher temperature is favor for propane or butane conversion.Methane is activated by C2H4 or light alkane. When the feedis CH4+C2H4+N2, the results are very good that methane conversion is 37.9%;aromatic yield is 60.0% and the aromatics selectivity is 79.6% at 520℃ over 0.2%Ga/HZSM-5 catalyst. When the feed is CH4+C2H4+N2, the results are much better that methane conversion is 37.3%;aromatic yield is 60.6% and the aromatics selectivity is 72.9% at 450°C over 0.1%Gd-1.35%Zn/HZSM-5 catalyst.these are better than the report that methaneconversion is 36.3% at 600℃. Nearly the same methane conversion but the temperature is respectively lower 80℃ and 150℃ than that report. The lifetime of the reason of high methane conversion is explained by XRD spectra.When the feed is CH4+C3H8+N2, the experimental results have not showed methane is actived by propane.the. The value of methane conversion is negative and the methane suppresses the propane. It may be propane has two routes that splits itself and actives methane. At experimental conditions, the splitness is prior to activing methane.So the value of methane conversion is negative.When the feed CH4+C4H10+N2, the results have showed that methane conversion is -9.8% at CH4/C4H10=0.45 but methane conversion increases to 6.9% at CH4/C4H10=3.125 at 450℃ over 0.1%Gd-1.35%Zn/HZSM-5.It is probably that the more amount of methane is easily activated by butane. This phenomenon is consistent with propane. Maybe there is thermodynamic balance of methane with propane or butane.The results of CO2 in aromatization have showed that different catalysts have differnt catalytic effects due to their dfiffernt structure, diverse character and various content etc when we study aromatization of methane, ethylene and propane.