| In molten salt,it is a novel technology to use partial oxidation of methane(POM)to synthesis gas with lattice oxygen.It can avoid hot spots and explosion of POM to synthesis gas.And oxygen catalyst can spread highly in the molten salt,increasing the conversion of CH4,H2 and CO selectivity and so on.The principle of technology,tester and the system of molten salt has been simply introduced in this paper.Oxygen carrier,supporting and improving of oxygen carrier have been studied. CeO2 as source of lattice oxygen to POM to synthesis gas is prepared mixed with MgO,TiO2 and Al2O3 as supported by incipient wetness impregnation, which were investigated by XRD,SEM-EDS,TPD and BET.The conversion of CH4,H2 and CO selectivity are measured on these prepared CeO2-based oxygen carrier under different reaction temperatures.The results showed the raising of reaction temperature had little effect on the methane conversion and H2 selectivity of 10%CeO2/MgO catalyst,and the content of CO was too low to be detected at the begin of reaction:Above the 825℃the methane conversion and H2 selectivity of 10%CeO2/Al2O3 catalyst had not conspicuous differ from 10%CeO2/MgO oxygen carrier,but the methane conversion and H2 selectivity of 10%CeO2/Al2O3 oxygen carrier were more higher than 10%CeO2/MgO oxygen carrier as raising of reaction temperature,and 10%CeO2/Al2O3 oxygen carrier had the biggest area surface;The reactive of 10%CeO2/TiO2 oxygen carrier is lower,and the methane conversion,H2 and CO selectivity were lower then 10%CeO2/Al2O3 oxygen carrier.The other important criterion of oxygen carriers is the circulation performances.The CeO2-based oxygen carriers are made by machine mixed and incipient wetness impregnation;The circulation performances of CeO2-based oxygen carriers which are investigated by TG experiment.The result found that the oxygen carriers that are made by incipient wetness impregnation showed better reactive than oxygen carriers are made by machine mixed.10%CeO2/ Al2O3 oxygen carriers show the best cycle performance,dropping 6%after five times cycle reaction,and spending the whole time of five reaction is the least.CeO2-based oxygen carriers in experiments with Al2O3 as supports were prepared at the temperatures of 650℃,750℃,850℃,950℃.The methane conversion and H2,CO selectivity are measured on these prepared CeO2-based oxygen carrier under different reaction temperatures.The results shows that the prepared 10%CeO2/Al2O3 oxygen carrier at the 750℃has the best reactive and the conversion of CH4 reach to 96.5%at the reaction temperature 825℃,and the selectivity of H2 is higher than others,but the selectivity of CO only is 40.1%.The effect of MgO and TiO2 as additive in 10%CeO2/ Al2O3 oxygen carrier,which made in 750℃were investigated and the different contents of MgO and TiO2 were measured in the experiment.The results indicated that the additives of MgO and TiO2 could improve the performance of oxygen carrier,3%TiO2 on10%CeO2/ Al2O3 oxygen carrier show relatively more reactive,the methane conversion and H2, CO selectivity reach to 89.35%,88.95%and78.68%at reaction temperature 900℃,respectively.The 3%MgO was equipped with the best reactive,the conversion of CH4,H2 and CO selectivity reach to 95.03%,93.45%and 93.42% at reaction temperature 900℃,respectively.In conclusion,the technology of partial oxidation of methane to synthesis gas,using lattice oxygen in molten salt is feasible,3%MgO as additives on 10%CeO2/ Al2O3 oxygen carrier is appropriate for partial oxygen methane to synthesis gas. |
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