Study On The Catalyst For Oxidative Dehydrogenation Of Propane To Propene

Propene is a very important raw material in the chemical industry and is wildly used in the industry production.Due to the rapid increase in propene demand,the propane catalytic dehydrogenation has become an important way to produce propene.Propane catalytic dehydrogenation is an endothermic and reversible reaction.The propane conversion is restricted by the thermodynamic equilibrium and the reaction is very energy-consuming,while the oxidative dehydrogenation of propane can break the thermodynamic equilibrium and reduce energy consumption.In this thesis,research has been carried out on the Mo-based catalyst for oxidative dehydrogenation of propane.XRD?FT-IR?H₂-TPR?NH₃-TPD were employed to characterize the properties of the catalyst.Oxidative dehydrogenation performance of Mo-based catalysts supported on different supports was investigated.Al₂O₃ was proven to be the best support.Al₂O₃ supported catalyst with 18 wt%MoO₃ loading exhibited the best performance?with propane conversion of 22.18%and propene yield of 14.01%at 550??compared with catalysts with other loadings.And this catalyst was the most active one with the highest acid amount.Mo-O-Al structure was speculated to be the active site.The formation of MoO₃ crystle can lower the activity of catalyst and facilitate the deep oxidative reaction.The catalysts with lower MoO₃ loading exhibited better stability during reaction.The investigation of Mo-based catalyst calcination temperature showed that higher calcination temperature led to poor Mo dispersion.The acid amount of the catalyst decreased as the calcination pemperature increased.The catalyst calcined under 550?exhibited the best performance.The optimal reaction conditions were as follows:reaction temperature=550?,C₃H₈/O₂=5/1?molar ratio?,GHSV=1200 h^-1.The performance of the Mo-based catalyst can be recovered after regeneration.The comparison between propane oxidative dehydrogenation and lattice oxygen oxidative dehydrogenation showed that the performance of oxidative dehydrogenation surpassed that of lattice oxygen oxidative dehydrogenation when the reaction temperature was higher than 600?.When the reaction temperature was lower than 600?,lattice oxygen oxidative dehydrogenation showed better performance.The introduction of oxygen can reduce the formation of CH₄,C₂H₄ and C₂H₆.The performances of Co-based and Co-Mo based catalyst were inferior to Mo-based catalyst.Hower,the addition of Co can improve the stability of Mo-based catalyst.