Steady-state kinetic model

The calculated conversions presented in Table VIII used Eq. (57). They are quite remarkable. They reproduce experimental trends of lower conversion and higher peak bed temperature as the S02 content in the feed increases. Bunimovich et al. (1995) compared simulated and experimental conversion and peak bed temperature data for full-scale commercial plants and large-scale pilot plants using the model given in Table IX and the steady-state kinetic model [Eq. (57)]. Although the time-average plant performance was predicted closely, limiting cycle period predicted by the... 

Model dynamics were forced to steady state by setting derivatives for the melt complexes in Eq. (61) to zero (Bunimovich et al., 1995). This should make the model behave as though the steady-state kinetic model... 

Fig. 17. Comparison of the variation of the time-average S02 conversion and the maximum bed temperature predicted for stationary cycling condition by an unsteady-state and a steady-state kinetic model for a packed-bed S02 converter operating with periodic flow reversal...

As shown in Fig. 14, the cathode potential changes abruptly across the H2/air-front. This fact warrants the inclusion of the pseudocapacitance into the previous steady-state kinetic model.12 It is clear that the electrode s pseudo-capacitance can supply protons in transient events and thereby reduce the cathode carbon-support corrosion rate in the case of fast moving H2/air- ronts. Figure 18... 

Let us consider the catalytic isomerization reaction whose steady-state kinetic model has already been considered in the previous section. Its detailed mechanism is of the form (1) A + Z AZ (2) AZ = BZ (3) BZ B + Z. Under the assumption of constant concentrations of substances in the gas phase, it will be written as... 

A non-steady-state kinetic model for a complex catalytic reaction with a linear mechanism is described as... 

Equation (102) is the non-steady-state kinetic model for the conversion of intermediates (for heterogeneous catalysis, for the conversion of surface substances) assuming that the concentrations of the observed substances are constant. As is known, the solution of eqn. (102) is of the form... 

The two-route mechanism (1) was qualitatively substantiated by Winter-bottom [45], A system of steps corresponding to this mechanism was first given by Kuchaev and Nikitushina [46] who also studied a steady-state kinetic model. Rate constants for mechanism (1) were reported by Cassuto et al. [48, 49, 65,107,108]. All except k3 were determined using the molecular beam method. The value for k3 was obtained from the solution of the inverse problem. It is these constants that will be applied by us here. 

K. M. Vanden Bussche and G. F. Froment, A steady-state kinetic model for methanol synthesis and the water gas shift reaction on a commercial Cu/ZnO/Al203 catalyst, ]. Catalysis, 161, 1-10 (1996). 

Steady state kinetic modeling does not yield the value of the site density Nj separately, but always in combination with rate parameters, see eqs 14-19. Only selective poisoning experiments and transient kinetic techniques can yield this information [65, 66], Maat-man [67] has analyzed many catalytic systems and gives a (broad) range of acceptable values for site densities L (sites per cm2), included in Table 2. 

In this study the steady-state kinetic model for the methanol synthesis on a commercial Cu/Zn0/Al203 catalyst developed by Vanden Bussche and Proment [13] are used. 

Vanden Bussche KM, Proment GF (1996). A Steady-State Kinetic Model for Methanol Synthesis and the Water Gas Shift Reaction on a Commercial CujZnO MiOi, Catalyst. Journal of Catalysis 161(156) 1-10, Academic Press Inc... 

A30. Augustinsson, K. B., Bartfai, T., and Mannervik, B., A steady state kinetic model of butyrylcholinesterase from horse plasma. Biochem. J. 141, 825-834 (1974). 

If the equilibrium adsorption-desorption assumption (EADA) is relaxed, then a more complicated kinetic model is obtained. The simplest way to relax this assumption is to replace it by a steady state assumption (SSA), that is assuming that the catalyst surface is at steady state. Both assumptions are strictly valid only for steady state conditions and cannot be used rigorously in the dynamic modelling of catalytic reactors. However, because of the complexity of the system and the lack of sufficient knowledge on the dynamics of the CSD processes, steady state kinetic models are usually used for dynamic modelling of catalytic reactors. 

Dubner, Poehlein, and Lee (20) developed a steady-state kinetics model for a single, seed-fed CSTR on the basis of the O Toole-Ugelstad concepts. Dimensionless groups analogous to a, ... 

In photochemical experiments, this very simple approach may be compromised if desorption of the reactants is fast, in that reactant adsorption-desorption equilibrium is not established during the reaction [then equation (13.5) does not hold]. In addition, active center reactivity is continuous because of continuous illumination thus, no equilibrium is established. This may lead to the derivation of a pseudo-steady-state kinetic model [200,201] with a rate expression slightly different from equation (13.4), the discussion of which is, however, out the scope of this work. 

Fig. 5. Effect of cycle period and inlet SO2 concentration on the performance of flow reversal reactor. (1-3) SO2 conversion predicted with dynamic kinetic model, (l -3 ) SO2 conversion predicted with steady-state kinetic model. (1,1 ) 9 % SO2 in the reactor inlet, (2,2 ) 6 % SO2, and (3,3) 3 % SO2.

Let s analyze the steady-state kinetic model, that corresponds to the well-known adsorption catalytic mechanism (Langmuir-Hinshelwood mechanism) l)2Z-(-02 2ZO ... 

Let us explain one of the most efficient applications of graph theory in chemistry. A steady-state kinetic model for intermediate j can be represented by the following equation ... 

The steady-state kinetic model of the general Temkin-Boudart mechanism is written in accordance with the mass-action law as... 

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