Study effect of catalyst shape on the ethylbenzene dehydrogenation in fixed bed reactor by using various mathematical models

Abstract

Nowadays, the chemicals are mostly manufactured by catalytic reactions in fixed bed reactor. Catalyst shape affects to reactor performance and the effect is studied by mathematic models which are varied forms to more realistic. Therefore, the objective of research is to study the effect of catalyst shape on the behavior of reactor for ethylbenzene dehydrogenation to styrene in gas phase by varied form. The simplest model, pseudohomogeneous model (model1), predicts 36.52% ethylbenzene conversion. The more complex model, heterogeneous model accounting for internal mass transfer (model2), predicts 34.49% conversion that equals to the model accounting for internal mass and heat transfer(model3). This result shows that internal mass transfer affects to overall the reaction. The more complex, heterogeneous model accounting for internal and external transfer(model4), predict 34.46% conversion. Addition of axial mixing to model3 and model4, both results are 34.46% conversion. Thus, external transfer and mass axial dispersion are little effect. Effect of catalyst shape on reactor performance is studied by varied form of heterogeneous model. The results of each models are little different. For the catalyst shape of same equivalent diameter, the required catalyst weight to achieve specific conversion increases in order trilobe < sphere < cylinder since the catalyst shape affects on effectiveness factor and pressure drop.