Study On The Construction And Reaction Characteristics Of Catalytic - Oxygen Bifunctional Materials For Chemical Circulation Dry Gas Reforming

As a new type of CO2 capture technology, Chemical Loop Dry Reforming (CLDR) can not only realize the efficient utilization of carbonaceous fuel, but also achieve low-cost CO2 capture and directional transformation. And in the CLDR system, the key to determine its reaction is oxygen carrier, whose essence is the redox catalyst. Thus, this paper has explored the microstructure、chemical state and oxygen mobility of catalysis-oxygen carrying dual functional materials in CLDR system to provide some scientific evidence for developing the efficient and highly reactive oxygen carriers.Three different oxygen carriers which were Fe2O3/Al2O3、ABO3 and LaFe3Al9O19 were prepared by coprecipitation method, and calcined at different temperature. For different series of oxygen carriers they were characterized by means of X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) and scanning electron microscopy (SEM) to analyze their physical and chemical properties.In accordance with the requirement of the reaction of Chemical Loop Dry Reforming (CLDR), a set of independently laboratory equipment was set up, and the equipment was used to evaluate the activity of the prepared oxygen carriers. We have investigated the conversion of methane、the selectivity of hydrogen and the ability to activate CO2 after the loss of lattice oxygen, and analyzed them associating their physical and chemical properties.The study has discovered that oxygen carriers at moderate calcination temperature of 900 ℃～1000℃ for Fe2O3/Al2O3 had high and stable activity, while the samples at the high calcination temperature showed a large sintering area, behaving a low activity. In spite of the small specific surface area of perovskite, both activity and stability were better than Fe2O3/Al2O3, especially in the cycle experiments, perovskite samples at the calcination temperature of 1100℃ revealed a high reaction activity and cycle stability. The conversion of methane in the reaction stayed above 60% all the time. But it was found that perovskite presented collapsing phenomenon for many times during the experiment. LaFe3Al9O1g showed a favorable activity and stability of high temperature compared to Fe2O3/Al2O3 and perovskite. Even though calcination temperature was 1200℃, LaFe3Al9O19 still remained a high specific surface area (10 m2/g). And it’s three times as much as Fe2O3/Al2O3 at the same calcination temperature. When the calcination temperature was 1000℃～1100℃, the samples presented a high methane conversion and hydrogen selectivity. In the first 7 min of reaction, the methane conversion of samples at the calcination temperature of 1000℃ all was 100%. Especially, even though the calcination temperature reached 1200℃, LaFe3Al9O19 also showed high selectivity of H2, which was more than 90% in 10 min of the reaction. This is due to the unique structure of the LaFe3Al9O19, which made it still contain a lot of lattice oxygen at high calcination temperature. Therefore, LaFe3Al9O19 showed good reaction activity.In short, after comprehensive comparison to sintering resistance, reaction activity and cycle stability, LaFe3Al9O19 is superior to Fe2O3/Al2O3 and perovskite.