Catalytic pellets

Fig. 6. The activity and selectivity with catalytic pellet size.

Porous catalytic pellets, 25 271-272 Porous electrodes, 3 428-429 Porous glass, 22 394 Porous graphite, 12 747 Porous hydrogels, for tissue engineering, 13 750-751... 

Decomposition of hydrogen sulfide. Mo 2 catalytic pellets packed on the shell side of the reactor. 

Dehydrogenation of ethylbenzene to styrene. Lio.5Fe2.4Cro.1O4 with 12wt.% K2O and 3wt.% V2O3 catalytic pellets packed on reactor shell side. 

Dehydrogenation of cyclohexane Pt/Al20j catalytic pellets packed on tube side. 

Dehydrogenation of cyclohexane Pt/Al203 catalytic pellets (0.5 wt.% Pt) packed on lube side. 

The Heat Balance Model Equations of the Catalytic Pellet BVP... 

Non-Isothermal Mass and Heat Balance Model of the Catalytic Pellet BVP with Finite External Mass and Heat Transfer Resistance... 

Suggest a sequence of steps for the solution of the design equations (for the reactor, jacket, catalytic pellet, 77, etc). 

Figure 5-17 Typical experiments with a single porous (catalytic) pellet.102 (a Dynamic VVicke-Kallenbach experiment for single-pellet-response experiments, (h) closed-chamber experiment for a single pellet.

Figure 7.5 Mechanisms of mass transfer for catalytic pellets. (Source Ref. 18 with permission).

The pseudo-homogeneous assumption means that both the solid and fluid phases are are considered a single phase. Therefore, we avoid considering mass and heat transfer from and to the catalytic pellets. This model assumes that the conqionent concentrations and the temperature in the pellets are the same as those in the fluid phase. This assumption is approximated when the catalyst pellet is small and mass and heat transfer between the pellets and the fluid phase are rapid. The reaction rate for this model, called the global reaction rate, includes heat and mass transfer. If heat and mass transfer are made insignificant, then the reaction rate is called the intrinsic reaction rate. 

C. Changes in the Liquid Composition Within Transport-Limited Catalytic Pellets... 

Trickle-bed reactor—A packed bed where a liquid reactant is fed from the top, wetting catalytic pellets and a gas reactant, fed either from the top or... 

The ammonia synthesis reaction is an exothermic reversible reaction that is carried out in a packed-bed of catalytic pellets. The removal of the heat generated by the reaction is the dominating factor in the design of the reactor. Since the... 

An alternative approach is to express the results in analogy with those for catalytic systems, in terms of an effectiveness factor (Ishida and Wen, 1968). Unlike in catalytic pellets, here the rate changes with time. Hence, the effectiveness factor also changes with time (i.e., with r,), and the following equation can be derived for a first-order reaction in a sphere ... 

A photograph of different types and sizes of catalyst is shown in Figure 10-5(a). A schematic diagram of a tubular reactor packed with catalytic pellets is showm in Figure I0-5(b). The overall process by w-hich heterogeneous catalytic reactions proceed can be broken down into the sequence of individual steps shown in Table 10-2 and pictured in Figure 10-6 for an i.somerizalion reaction. 

The catalytic pellet may be considered to be spherical with equivalent radius Rp. 

Taking into account diffusion processes, this approach permitted to predict that catalytic pellets with different, independently varying profiles of Co and Mo, should have very different HYD/HDS selectivities, and this was verified experimentally (9,13). 

The behaviour of the catalytic bed during periodic operation can be explained by means of a simple phenomenological model (Gabarain et al, 1996). Consider a catalytic pellet, as shown in Figure I. During the wet cycle (Zone A) the pellet is completely wet, the dissolved gas... 

Watson P.C. and M.P. Harold. Dynamics Effects of Vaporization with Exothermic Reaction in a Porous Catalytic Pellet . AIChE J 39,6 (1993). 

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