Dehydrogenation Kinetic Model Of Heavy Paraffin With Different Carbon Number

Linear Alkyl Benzene(LAB)is an important raw material for the production of alkylbenzene sulfonate,which is a type of surfactant in detergents.Dehydrogenation of heavy paraffins to manufacture mono-olefins is an important process for industrial production of synthetic detergents.The dehydrogenation process is a complex reaction system where the mono-olefins yield and the catalyst service time are affected by the reaction conditions.Meanwhile the content of paraffins with different carbon number in the raw materials also has a certain influence on product distribution.Therefore,the study on dehydrogenation kinetics of heavy paraffins with different carbon number on industrial degree has certain practical significance.In this paper,the experimental data of heavy paraffins dehydrogenation to manufacture mono-olefins with different carbon number C10,C12,C13 were provided by LAB plant of Jinling Petrochemical Corporation of Sinopec.Based on the dehydrogenation mechanism of heavy paraffins under industrial conditions,the intrinsic reaction kinetic model and catalyst deactivation model were established considering the influence of side reactions with different carbon-number heavy paraffins.Powell optimization method was used to estimate the model parameters.The result of linear regression analysis of the relationship between the activation energies and pre-exponential factors of homologous reactions and carbon number of paraffins showed the mathematical expression was reasonable,and the correlation coefficient was more than 0.99.The correlation model between liquid hourly space velocity,reaction temperature,carbon number and deactivation rate constants was established under the fixed pressure and fixed hydrogen hydrocarbon molar ratio.The correlation model was validated under the reaction conditions which differ from those for parameter estimation,the results showed that the average relative deviation of paraffins was 1.432%in the paraffins mixture(C10-C13),the average relative deviation of mono-olefins was 3.179%,and the average relative deviations of diolefins and aromatics were 7.353%and 5.695,respectively.The fitting effect of experimental values and calculated values is good.The product distribution of paraffins mixture C9-C14 was predicted according to the established intrinsic kinetic model,catalyst deactivation kinetic model and correlation model.The results of this study can provide theoretical support for reactor simulation and operating condition optimization of industrial heavy paraffin catalytic dehydrogenation.