Research On Preparation Of Ce-based Oxygen Carrier By Direct Ball Milling Method For Chemical Looping Reforming Of Methane

Chemical looping reforming of methane to syngas is a novel technology for methane conversion.In this technology,lattice oxygen of oxygen carrier is used to provide oxygen source for reforming reaction,and carbon dioxide is used to oxidize and regenerate lattice oxygen of oxygen carrier.In this paper,the preparation and experimental conditions of oxygen carriers were systematically studied in the reaction process of methane chemical looping reforming to syngas.Firstly,Ce_x Fe_?10-x?O??x=5,6,7,8?composite oxygen carriers and pure CeO₂ and Fe₂O₃oxygen carriers were prepared by direct ball-milling method,and the reactivity of oxygen carriers was investigated in a fixed-bed reactor.The results show that compared with pure CeO₂ and Fe₂O₃ oxygen carriers,the cerium-iron composite oxygen carriers exhibited better reactivity,and the Ce₇Fe₃O?oxygen carrier exhibited the best catalytic activity.The effects of calcination temperature and reaction temperature on the reactivity of Ce₇Fe₃O_?carrier were investigated.It was found that when the calcination temperature was 900°C and the reaction temperature was 850°C,the Ce₇Fe₃O?carrier exhibited the best reaction performance.Secondly,in order to further improve the reaction performance of Ce₇Fe₃O?oxygen carrier,the Ce₇Fe₃M_xO??M=Cu,Co,Zr,x=0,0.1,0.5,1?composite oxygen carriers were prepared by direct ball-milling method,and the effect of adding different metals on the reaction performance of Ce7Fe3O?oxygen carrier was investigated.The results show that the Ce₇Fe₃Cu_0.5O?,Ce₇Fe₃Co_0.1O?,Ce₇Fe₃Zr_0.5O?oxygen carriers exhibited the best reaction performance in isothermal experiments,and the carbon monoxide selectivity is increased by15%,9%and 10%,respectively,compared with the Ce₇Fe₃O?carrier.The effects of calcination temperature and reaction temperature on the catalytic activity of Ce₇Fe₃Cu_0.5O?,Ce₇Fe₃Co_0.1O_?and Ce₇Fe₃Zr_0.5O_?oxygen carriers were investigated in the following experiments.It was found that the addition of Cu,Co and Zr reduced the calcination temperature of the oxygen carrier and the optimum calcination temperature was 800°C.The recyclable stability of Ce₇Fe₃Cu_0.5O?,Ce₇Fe₃Co_0.1O?and Ce₇Fe₃Zr_0.5O?oxygen carriers were investigated.It was found that the Ce₇Fe₃Cu_0.5O?oxygen carrier exhibited the best recyclable stability.Finally,the oxygen carriers were characterized by XRD,H₂-TPR and O₂-TPO.The results showed that the reaction performance of the oxygen carriers was improved after the addition of Cu,Co and Zr,and their oxygen storage capacity and lattice oxygen release capacity were improved.After the addition of Cu,the temperature range of the reduction peak of the oxygen carrier moves to the low temperature region,which improved the reducibility of the oxygen carrier and made it have better reactivity.The oxygen storage capacity of the oxygen carrier was measured,and it was found that the oxygen storage capacity of the oxygen carrier was significantly increased after the addition of the metal,which was beneficial for the reforming reaction to generate carbon monoxide.