A Packed-Bed Reactor

Olefin Amination (Method 6). The most recent technology for the production of lower alkylamines is olefin amination (14). This is 2eohte-cataly2ed reaction of ammonia with an olefin, eg, isobutylene, and is practiced in a packed-bed reactor system in the vapor phase. 

Unsteady-State Direct Oxidation Process. Periodic iatermption of the feeds can be used to reduce the sharp temperature gradients associated with the conventional oxidation of ethylene over a silver catalyst (209). Steady and periodic operation of a packed-bed reactor has been iavestigated for the production of ethylene oxide (210). By periodically varyiag the inlet feed concentration of ethylene or oxygen, or both, considerable improvements ia the selectivity to ethylene oxide were claimed. 

Problems are stiff when the time constants for different phenomena have very different magnitudes. Consider flowthrough a packed bed reactor. The time constants for different phenomena are ... 

TABLE 7-10 Material and Energy Balances of a Packed Bed Reactor... 

As well as being active, the immobilised enzyme also needs to be stable (active for a long period) and the support must promote this. The support must also have appropriate mechanical characteristics it should not disintegrate if used in a stirred tank reactor it should produce even flow (without channelling) in a packed bed reactor. Hie cost of the support is also important. 

The next example applies this general procedure to a packed-bed reactor. 

Consider an observed reaction of the form A + B P + Q occurring in a packed-bed reactor. 

Suppose that catalyst pellets in the shape of right-circular cylinders have a measured effectiveness factor of r] when used in a packed-bed reactor for a first-order reaction. In an effort to increase catalyst activity, it is proposed to use a pellet with a central hole of radius i /, < Rp. Determine the best value for RhjRp based on an effective diffusivity model similar to Equation (10.33). Assume isothermal operation ignore any diffusion limitations in the central hole, and assume that the ends of the cylinder are sealed to diffusion. You may assume that k, Rp, and eff are known. 

Example 11.10 Determine phase concentrations for a liquid-liquid reaction in a packed-bed reactor. The reactive component is dilute in both phases. It enters the reactor in one phase but undergoes a pseudo-first-order reaction in the other phase. All parameters are constant. 

Another important challenge is to enhance the reliability of the design and scale up of multi-phase reactors, such as fluidized bed reactors and bubble-colunms. The design uncertainty caused by the complex flow in these reactors has often led to the choice of a reactor configuration that is more reliable but less efficient. An example is Mobil use a packed-bed reactor for the methanol to gasoline process in New Zealand, even though a... 

A commercial pectinase, immobilised on appropriately functionalised y-alumina spheres, was loaded in a packed bed reactor and employed to depolymerise the pectin contained in a model solution and in the apple juice. The activity of the immobilized enzyme was tested in several batch reactions and compared with the one of the free enzyme. A successful apple juice depectinisation was obtained using the pectinase immobilised system. In addition, an endopolygalacturonase from Kluyveromyces marxianus, previously purified in a single-step process with coreshell microspheres specifically prepared, was immobilised on the same active support and the efficiency of the resulting catalyst was tested. 

Kim JH, Oh KK, Lee ST, Kim SW, Hong SI (2002) Biodegradation of phenol and chlor-ophenols with defined mixed culture in shake-flasks and a packed-bed reactor. Process Biochem 37(12) 1367-1373... 

If the measuring points are chosen far enough away from the ends of the test vessel so that end effects are negligible, this expression may be used with confidence. Bischoff and Levenspiel (12) have presented design charts that permit one to locate monitoring stations so as to avoid end effects. For example, in a packed bed reactor with a tube to pellet diameter ratio of 15, where the packed bed is followed by an open tube, at least 8 pellet diameters are required between the measurement point and the open tube if errors below 1% are to be obtained. 

The following data have been reported as a result of an effort to determine the distribution of residence times in a packed bed reactor. Use these data to generate an F(t) curve and to determine the average residence time in the reactor. 

Itoh, N., Nakamura, M., Inoue, K. and Makino, Y. (2007) Continuous production of chiral 1,3-butanediol using immobilized biocatalysts in a packed bed reactor promising biocatalysis method with an asymmetric hydrogen-transfer bioreduction. Applied Microbiology and Biotechnology, 75 (6), 1249-1256. 

Resmi CS, Shaffiqu TS, Roy JJ et al (2008) Aerobic degradation of a mixture of azo dyes in a packed bed reactor having bacteria coated laterite pebbles. Biotechnol Prog 19 647-651... 

One-dimensional representation of the propagation of a concentration step-disturbance in a packed bed reactor (5). 

A packed bed reactor has an RID like that of a five stage CSTR. The rate equation is... 

Figure 4.15 Performance of the basic system when operated as a packed bed reactor (n = 3). Concentrations of all the reactants are indicated for the reactor outlet. The values of aU parameters used are given in Table 4.1, set I.

Figure 4.68 Configuration employed for operation of the basic system as a packed bed reactor. (.) control...

Figure 4.69 Experimental and theoretical results obtained for the basic system with G6PDH and GR when operated as a packed bed reactor. Theoretical results were obtained with n = 5 (i.e., assuming plug flow regimen), Fm.oepDH = 0.6 mM/min and = 0.7 mM/min and considering G6P as an inhibitor of GR with the values of indicated.

Table 4.12 Numerical Values of the Operational Parameters Used in Simulations of the Extended Basic System When Operated as a Packed Bed Reactor...

The calculations discussed above (Figures 4.72 to 4.77) were performed for a PFR. Figures 4.78 to 4.80 refer to a packed bed reactor with n = 3. In this case the effect of the concentration range of the external inhibitor on the signal obtained was investigated. The data in Figures 4.78 to 4.80 differ from one another with respect to the cycle time, r, of the concentration profile of... 

---