| Shale gas and natural gas is a major gas resources, its contain mainly methane of mixed light alkanes and CO2etc. methane is a kind of non-polar hydrocarbon and its molecular structure is highly symmetrical, so making it have high stability,key technology is implemented of methane activation and selective transformation in the process of reaction that putting a carbon material into other high value-added chemical products.Indirect conversion of methane was become the most effective way for activation of methane to use.it is firstly CH4into syngas, then the syngas transform into other chemical products.Methane to syngas basically has three methods:Steam reforming of methane (SRM), Partial oxidation of methane (POM) and Carbon dioxide reforming of methane (CDM).Based on the existing disadvantages of POM and CDM reaction and the defect of nonmetal catalyst in the process of reaction, This experiments were investigate catalytic activity and ability to resist coking for Ni-(Ce-La-Mg)/Support and Ni-La/CexZr1-xO2in coupled methane partial oxidation and CH4/CO2reforming.At the same time the catalysts were characterized combined with N2isothermal adsorption-stripping (BET), scanning electron microscopy (SEM), hydrogen temperature programmed reduction (H2-TPR), X-ray diffraction (XRD) and thermogravimetric (TG) analysis, etc.The main results are as follows:(1) It was studied that the effect of Ni-(Ce-La-Mg)/Support catalysts on catalytic performance.Under the condition of high temperature reaction, Ni/γ-Al2O3because of its the right specific surface area and pore structure, make it has the best catalytic reactivity; Additives(Ce, La) can obvious promote the conversion and selectivity of catalysts;Under the condition of catalyst loading quantity is0.3g,airspeed:2.54X104mL/(h.g cat);CH4/CO2/O2/N2=50:20:17:40(mL/min),reaction temperature:800℃,Ni-Ce-La-Mg-γ-Al2O3catalyst due to the combined action of its support, additives and active component, XCH4=89.12%and YH2=75.86%achieves the maximum value, XCO2=95.32%and YCO=81.22%have excellent stability compared with other catalysts;The best load of nickel was10%, the best reaction temperature was800℃,H2/CO ratio can be maintained1～2by adjusting the ratio of feed gas.(2) Ni/γ-Al2O3catalyst obviously turn black after6h reaction, the TG analysis has serious carbon deposition behavior.After modified with additives of Ni-Ce-La-Mg-γ-Al2O3has stronger stability of catalyst during the entire test,and the before and after reaction generated almost no carbon deposit.That explain add additives can obviously enhance the resistance to carbon deposition of catalyst performance.(3) In the research of catalytic performance of Ni-La/CexZr1-xO2(X=0,0.16,0.5,0.75,1):because of the difference of Ce/Zr ratio, specific surface area of the carrier and Pore structure parameters have very big difference, Ce0.75Zr0.25O2has the most specific surface area of43.10m2.g-1;The formation of cerium zirconium solid solution and additives of La can enhance the degree of dispersion of active components, NiO crystals size can reach minimum13.7nm;Ni-La/Ce0.75Zr0.25O2has the best catalytic activity, XCO2=81%、XCH4=76%'SCO=95.77%、SH2=90%.(4) Ni-La/Ceo.75Zro.2502still has a stable catalyst performance after60h stability test.The TG-DSC and XRD (After the reaction catalyst)shows: the amount of carbon deposit catalyst was7%, the active component crystals size have not changed much before and after the reaction.Ni-La/Ceo.75Zro.2502catalyst can significantly reduce the amount of carbon deposit, it alleviate the deactivation phenomenon caused by carbon deposition reaction and has strong ability to Sintering resistance. |
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