The Studies Of Heavy Aromatics Hydrodealkylation Over The Pt/MOR Catalyst

The heavy aromatics dealkylation can gain valuable organic chemicals,and the key of this process is to develop excellent performance of catalysts.In dealkylation reaction of the heavy aromatics,Pt/MOR catalysts exhibit an excellent catalytic performance.However,the high price and poor stability of the Pt/MOR catalyst limit its commercial application.Based on the excellent catalytic performance of Pt/MOR catalysts,using nano-hierarchical pore MOR zeolites as the supporter,Pt/MOR catalysts were prepared by the incipient impregnation in this dissertation,and were characterized by hydrogen chemical adsorption?XRD?Py-IR?NH₃-TPD?BET?SEM?TG,and using cumene as the probe molecule,the hydrodealkylated performance of the catalysts were evaluated in a continuous flow fixed-bed reactor.The influences of the impregnation methord?adding agents and competing sorbents on the Pt dispersion and the catalytic activity of the catalysts,and the influences of the agents on the stability of the catalysts were investigated,In addition,deactivation and regeneration of the catalysts were studied to establish the deactivation kinetics equation and carbon combustion kinetics.The study results of Pt dispersion showed that the degree of Pt dispersion and Pt/MOR catalytic performance were improved by high-frequency ultrasound?adding 0.8%Ni and citric acid.Pt dispersion increased from 6.0%to 48.2%by adding citric acid.The addition of agents and competing sorbents adjusted the acid properties and acid amount of the catalyst surface,increased the B acid and L acid,decreased the ratio of B acid/L acid,improved the catalytic performance.However,adding agents had no influence on the stability of the catalysts.The study results of deactivation kinetics of Pt/MOR catalysts showed that in the reaction of cumene hydro dealkylation,the effects of external diffusion on dealkylation reaction could be negligible and the internal diffusion had less impact on it.The deactivation kinetics data were obtained under the conditions of reaction pressure 0.8 MPa,reaction temperature 673.15 K⁷33.15 K,liquid hourly space velocity 1 h^-12 h^-1,and the deactivation kinetics model was established.The reaction rate equation of cumene hydrodealkylation reaction:???The deactivation rate equation of cumene hydrodealkylation reaction:???Rank and residual distribution test indicate that the deactivation kinetics model is prominent under the conditions of the significance level?=0.05,namely the deactivation kinetics model has a high fitting accuracy and credibility.The study results of carbon combustion kinetics of Pt/MOR catalysts showed that the main cause of Pt/MOR catalyst deactivation is that coke blocked the zeolite pore channels and covered the active sites of the catalyst.A regeneration process of coke combustion inside inside the rig under the conditions of temperature 500?,air flow 50 mL/min could recover the activity of deactivated catalyst effectively.The TG?NH₃-TPD?BET?Py-IR characterization results showed that after regeneration,the coke had been burned out mainly,the specific surface area and pore volume of the regenerated catalyst could recover to the level of fresh catalyst basically,the ratio of B acid/L acid of the regenerated catalyst was slihgtily different from that of the fresh catalyst,but the recovery of total asid amount was not good enough.Through analysing the change of coke content of the deactivated catalysts under different partial oxygen pressures,the carbon combustion kinetics of deactivation Pt/MOR catalyst was established as follows:???...