Study Of Monolithic Reactor For Dehydrogenation Of Propane And Ethyl Benzene

Monolithic and randomly packed fixed-bed reactors for propane dehydrogenation and ethyl-benzene dehydrogenation were simulated by COMSOL Multiphysics,and their performance was compared under isothermal and adiabatic conditions.Furthermore,the influence of stage number,process conditions and catalyst structure on the performance of adiabatic monolithic reactor was also investigated.For propane dehydrogenation process,higher propane conversion and propylene selectivity as well as lower pressure drop can be obtained in monolithic reactor compared with randomly packed reactors under both isothermal and adiabatic conditions.Under isothermal condition,the monolithic catalyst deactivation is faster than randomly packed catalyst,while an opposite result is found in adiabatic condition;by feeding at 873 K and 100 kPa,the propane conversion and propylene selectivity in a adiabatic four-stage randomly packed reactor are 30.51% and 87.99%,respectively,while the values in a adiabatic four-stage monolithic reactor are 34.83% and 89.30%,respectively;the propane conversion and propylene yield of a adiabatic four-stage reactor are 4.46% and 3.79% higher than a three-stage reactor,10.82% and 9.35% higher than a two-stage reactor and 20.22% and 17.84% higher than a one-stage reactor,respectively;increasing temperature and decreasing pressure can raise the conversion of propane,and lower temperature and pressure are favorable for higher propylene selectivity;reducing catalyst wall thickness can realize higher propane conversion and propylene selectivity,and an appropriate thickness is 0.2mm;the cell density of catalyst has little impact on the reactor performance.For ethyl-benzene dehydrogenation process,higher ethyl-benzene conversion and styrene selectivity as well as lower pressure drop can be obtained in monolithic reactor compared with randomly packed reactors under both isothermal and adiabatic conditions.By feeding at 893 K and 104 kPa,the ethyl-benzene conversion and styrene selectivity in a adiabatic two-stage randomly packed reactor are 56.70% and 92.15%,respectively,while the values in a adiabatic two-stage monolithic reactor are 68.89% and 93.50%,respectively;the ethyl-benzene conversion and styrene yield of a adiabatic three-stage reactor are 4.96% and 4.21% higher than a two-stage reactor,19.04% and 16.64% higher than a one-stage reactor,respectively;increasing temperature and decreasing pressure can raise the conversion of ethyl-benzene,and lower temperature and pressure are favorable for higher styrene selectivity;reducing catalyst wall thickness can realize higher ethyl-benzene conversion and styrene selectivity,and an appropriate thickness is 0.2mm;the cell density of catalyst has little impact on the reactor performance.