Catalytic reactor, isothermal heterogeneous

Elnashaie, S.S.E.R and Abdel-Hakim, M.N., Optimal Feed Temperature Control for Fixed Bed Non-isothermal Catalytic Reactors Experiencing Catalyst Deactivation. A Heterogeneous Model. Computers and Chem. Eng., Vol. 12, pp. 787-790, 1988. 

ISOTHERMAL DESIGN OF HETEROGENEOUS PACKED CATALYTIC REACTORS... 

ISOTHERMAL DESIGN OF HETEROGENEOUS PACKED CATALYTIC REACTORS d (Axial Grad) (Axial Grad)... 

Find the relation to predict the composition profile in a packed tube reactor undergoing isothermal linear kinetics with axial diffusion. The packed tube, heterogeneous catalytic reactor is used to convert species B by way of the reaction... 

Fig, 18 A general steady state isothermal heterogeneous dispersion (PD-)model for multiphase catalytic reactors... 

Advanced learners should then also study Section 4.11.4 (on transport limitations in experimental catalytic reactors) and Sections 4.11.5.2-4.11.5.4, where some more complex examples are given (heterogeneously catalyzed gas-phase reaction, catalytic multiphase reaction, and non-isothermal oxidation of carbon). 

Trickle-bed reactors, wherein gas and liquid reactants are contacted in a co-current down flow mode in the presence of heterogeneous catalysts, are used in a large number of industrial chemical processes. Being a multiphase catalytic reactor with complex hydrodynamics and mass transfer characteristics, the development of a generalized model for predicting the performance of such reactors is still a difficult task. However, due to its direct relevance to industrial-scale processes, several important aspects with respect to the influence of external and intraparticle mass transfer effects, partial wetting of catalyst particles and heat effects have been studied previously (Satterfield and Way (1972) Hanika et. al., (1975,1977,1981) Herskowitz and Mosseri (1983)). The previous work has mainly addressed the question of catalyst effectiveness under isothermal conditions and for simple kinetics. It is well known that most of the industrially important reactions represent complex reaction kinetics and very often multistep reactions. Very few attempts have been made on experimental verification of trickle-bed reactor models for multistep catalytic reactions in the previous work. 

Restelli and Coull [AIChE J., 72 (292), 1966] have studied the transmethylation reaction of dimethylamine in a differential flow reactor using montmorillonite as a catalyst. They measured initial reaction rates under isothermal conditions for this heterogeneous catalytic process. Steady-state operating data were recorded. 

In general, if heterogeneous catalytic reactions are to be conducted isothermally, the reactor design must provide for heat flow to or from the particles of catalyst so as to keep the thermal gradients small. Otherwise, temperatures within the catalyst bed will be non-uniform. The differential reactor and the various forms of the gradientless reactors are advantageous in this regard. 

In a recent survey [19] it was noted that a realistic model for catalytic oxidation reactions must include equations describing the evolution of at least two concentrations of surface substances and account for the slow variation in the properties of the catalyst surface (e.g. oxidation-reduction). For the synchronization of the dynamic behaviour for various surface domains, it is necessary to take into consideration changes in the concentrations of gas-phase substances and the temperature of the catalyst surface. It is evident that, in the hierarchy of modelling levels, such models must be constructed and tested immediately after kinetic models. On the one hand, the appearance of such models is associated with the experimental data on self-oscillations in reactors with noticeable concentration variations of the initial substances and products (e.g. ref. 74) on the other hand, there was a gap between the comprehensively examined non-isothermal models with simple kinetics and those for the complex heterogeneous catalytic reactions... 

H. Redlingshofer, O. Krocher, W. Bock, K. Huthmacher, G. Emig, Catalytic wall reactor as a tool for isothermal investigations in the heterogeneously catalyzed oxidation of propene to acrolein, Ind. Eng. Chem. Res. 41 (2002) 1445. 

In a recently published reactor design textbook, a problem begins as follows The heterogeneous gas-phase catalytic chemical reaction, A - - B C, is carried out in an isothermal isobaric flow reactor. If Q represents the molar density of species i, then the volume-based kinetic rate expression for the reaction is... 

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