Manganeses oxides (MnO_x) with different crystal and structural properties were prepared by the precipitation, the complex-decomposition, and the thermal decomposition methods, respectively. The materials were characterized by XRD, SEM, TEM, H₂-TPR, TG-DSC, XPS, and N₂ adsorption/desorption at low temperatures. The samples were comparatively evaluated as catalysts for the oxidative dehydrogenation of ethylbenzene with carbon dioxide (CO₂-ODEB). Results indicate that both Mn₂O₃ and Mn₃O₄ were active for CO₂-ODEB and the Mn₃O₄ prepared by the precipitation method showed the highest conversion of ethylbenzene over 60%. Moreover, the activity of MnO_x for CO₂-ODEB was significantly affected by the synthesis method and parameters of the oxides. The correlation between the reaction and characterization results indicates that the CO₂-ODEB over MnO_x may follow the redox mechanism involving the lattice oxygen, and the amount of the mobile oxygen species and the surface area were revealed to be key factors in determining the activity of the MnO_x catalysts for the titled reaction. Together with the characterization results of XRD, TG-DSC, and H₂-TPR, the irreversible reduction of MnOx to MnO under the conditions of CO₂-ODEB was the main reason for the deactivation of the catalyst while the coke deposition had a less important impact on the stability of the catalyst.

采用沉淀法，络合物分解法和热分解法分别制备了具有不同晶体和结构性质的锰氧化物（MnO _x）。通过XRD，SEM，TEM，H ₂ -TPR，TG-DSC，XPS和低温下的N ₂吸附/解吸对材料进行表征。对样品进行了比较评估，以作为乙苯与二氧化碳（CO ₂ -ODEB）氧化脱氢的催化剂。结果表明，二者的Mn ₂ ö ₃和Mn ₃ ö ₄分别为CO活性₂ -ODEB和MN ₃ Ò ₄沉淀法制得的乙苯转化率最高，超过60％。此外，MnO _x对CO ₂ -ODEB的活性受到氧化物的合成方法和参数的显着影响。反应与表征结果之间的相关性表明，MnO _x上的CO ₂ -ODEB可能遵循涉及晶格氧的氧化还原机理，并且活动性氧的数量和表面积是决定活性的关键因素。标题反应的MnO _x催化剂的制备。连同XRD，TG-DSC和H ₂的表征结果-TPR，在CO ₂ -ODEB条件下MnOx不可还原地还原为MnO是催化剂失活的主要原因，而焦炭沉积对催化剂稳定性的影响较小。