Coupling Reaction Of Propane Dehydrogenation With Carbon Dioxide Hydrogenation In Slurry-bed Reactor

The demand for propylene in the development of industry is increasing yearly,and Besides steam cracking and catalytic cracking,more methods are needed to meet the current demand for propylene.Propane dehydrogenation to propylene（PDH）technology is developing rapidly due to shale gas development,but the energy consumption of PDH is high due to the thermodynamic equilibrium limitation.On the other hand,using carbon dioxide as a reaction feedstock for hydrogenation to synthesize methanol,low-carbon olefins and aromatics is gaining importance.One of the factors limited the development of this technology is reducing the energy consumption for hydrogen production.Hydrogen from propane dehydrogenation coupling with carbon dioxide hydrogenation facilitates the PDH reaction to produce propylene and allows for the chemical conversion of carbon dioxide.Our group has conducted related research on the Fixed bed reactors and screened some catalysts with good activity.Slurry bed reactor has the advantages of high mixing intensity,high heat and mass transfer efficiency,uniform temperature distribution,simple operation,and low maintenance cost.Coupling reaction of propane dehydrogenation with carbon dioxide hydrogenation is less studied in slurry bed.Therefore,in this study,the coupling reaction of propane dehydrogenation with carbon dioxide hydrogenation in slurry bed was carried out to provide reference and primary research data for later industrial production.The main research contents were as follows:1.V-Fe/KIT-6 catalysts were prepared,and V-Fe/KIT-6 slurry catalysts were synthesized by sol-gel method.They were characterized by beans of XRD,XPS,NH₃-TPD,TG,SEM,N₂ adsorption/desorption.Their performance in the coupling reaction of propane dehydrogenation with carbon dioxide hydrogenation in slurry bed was investigated,and the effect of structural additives on catalytic activity was studied.Under the reaction conditions that reaction temperature is 260°C,activation time is 8 h,feed ratio is 1/3（volume ratio）,and airspeed is 6000 m L/（gcat·h）,conversions of propane and carbon dioxide are 78.0%and 12.9%,respectively.38.7%propylene yield and 49.6%propylene selectivity can be achieved over V-Fe/KIT-6 catalyst.Preparation of V-Fe/KIT-6 slurry catalysts with Tween 80 additive by sol-gel method can produce with 85.6%propane conversion,15.1%carbon dioxide conversion,55.6%propylene yield,and 65.0%propylene selectivity.2.Ga-（ZSM-5@SAPO-34）catalysts were prepared,and Ga-（ZSM-5@SAPO-34）slurry catalysts were synthesized by sol-gel method,They were characterized by beans of XRD,XPS,NH₃-TPD,TG,SEM,N₂ adsorption/desorption,Their performance in the coupling reaction of propane dehydrogenation with carbon dioxide hydrogenation in slurry bed was investigated,and the effect of structural additives on catalytic activity was studied.Under the reaction conditions that reaction temperature is 280°C,activation time is 6 h,feed ratio 1/3（volume ratio）,and airspeed is 7500 m L/（gcat·h）,conversion of propane and carbon dioxide are 64.2%and 7.2%,respectively.19.0%propylene yield and 29.6%propylene selectivity can be achieved over Ga-（ZSM-5@SAPO-34）catalyst.Preparation of Ga-（ZSM-5@SAPO-34）slurry catalyst with Tween 80 additive by sol-gel method can produce with 79.6%propane conversion,13.1%carbon dioxide conversion,32.9%propylene yield,and 41.3%propylene selectivity.3.The main reactions in the coupling reaction of propane dehydrogenation and carbon dioxide hydrogenation were selected using the idea of summation.The macroscopic kinetic model in the idealized state was established.The rationality of the reaction kinetics model was valued through residual sum of squares,regression mean square sum,and model residual mean square sum.The relative error between calculated and actual experimental values of propane and propylene is less than 20%.Reaction kinetic model can supply useful data for the reactor design and industrial scale-up for propane dehydrogenation coupled with carbon dioxide hydrogenation to propylene.