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Packed reactors conversion

Packed-bed conversion. Membrane reactor conversion. Molecular Sieve Silica. [Pg.223]

Thus, if the total reactor conversion is 90% the minimum recycle ratio for a first-order reaction should be at least 90 and for a second order reaction 180. This simple example demonstrates that large conversions in recycle reactors are as unfavorable as very small conversions in a packed bed differential reactor. If one is interested in the reaction rate at small concentrations of the reactants, these concentrations in the recycle reactor should be achieved by small or moderate inlet concentrations but not through a large conversion. Large recirculation ratios can be achieved by decreasing of the bed depth. [Pg.108]

Mohan and Govind [1988c] applied their isothermal packed-bed porous membrane reactor model to the same equilibrium-limited reaction and found that the reactor conversion easily exceeds the equilibrium value. The HI conversion ratio (reactor conversion to equilibrium conversion) exhibits a maximum as a function of the ratio of the permeation rate to the reaction rate. This trend, which also occurs with other reactions such as cyclohexane dehydrogenation and propylene disproportionation, is the result of significant loss of reactant due to increased permeation rate. This loss of reactant eventually negates the equilibrium displacement and consequently the conversion enhancement effects. [Pg.444]

In Fig. 5.18 IMRCF (s=l) corresponds to the PBMR with catalyst pellets with a non-uniform catalyst distribution, while CMR ( =1) is the CMR with the catalyst placed non-uniformly on the membrane surface in contact with the catalytic reactor feed. IMRCF (a(s)=I) and CMR (a( )=I) correspond to the PBMR and CMR with uniform catalyst distributions. The conventional packed-bed reactor (FBR in Figure 5.18) exhibits conversions, which are below the equilibrium conversion, and for large residence times are lower than those exhibited by the CMR and the PBMR. The highest conversions are obtained with the non-uniform activity (Dirac delta case) profiles. This result was explained on the basis that the access of the reactants to the active catalytic sites was not limited by diffusion. When the catalyst is uniformly distributed the PBMR exhibits better performances than the CMR. It is interesting to note that at low residence times the packed-bed reactor conversion is higher than that of the PBMR with a uniformly distributed catalyst this is because in this case for the PBMR the reactants are only partially in contact with the catalyst due to diffusional limitations. [Pg.201]

The nested packed reactor (Fig. 5A0d) allows sample pretreatment prior to injection by means of solid oxidants, reductants, ion exchangers, immobilized enzymes, or suitable surface-active sorbents. The potential of this approach is largely unexploited, since so far such sample pretreatment has been used only to remove unwanted matrix, which is not retained on the column, for sample preconcentration, and for analyte conversion in connection with AAS and ICP (cf. Chapter 4.7). [Pg.269]

Packed bed reactor The use of immobilized enzymes in packed bed reactors, by virtue of their similarity to chromatographic systems, has been particularly widely accepted. The size of the reactor can be determined by the volume of support necessary for complete conversion of substrate to product. The kinetic situation in a packed reactor with immobilized enzyme(s) is, however, rather more complex. For a low enzyme activity per unit mass of carrier, the interparticle mass transfer is unimportant. When higher carrier specific activities are prepared on... [Pg.435]

N2F4 was first prepared by thermal reaction of NF3 with various fluoride acceptors such as Cu, As, Sb, Bi, or stainless steel [1, 2]. Thus, N2F4 was produced in 62 to 71% yield based on NF3 consumed (42 to 62% conversion) in a Cu-packed flow reactor at 375°C with a residence time of 13 min [1,2]. Oxygen or nitrogen oxides are added to the NF3 to reduce the induction period of the reaction and residence time in the Cu-packed reactor [3]. Although Cu is the most effective in producing N2F4 the reaction is erratic and often leads to complete reduction of NF3 to... [Pg.300]

After the SO converter has stabilized, the 6—7% SO gas stream can be further diluted with dry air, I, to provide the SO reaction gas at a prescribed concentration, ca 4 vol % for LAB sulfonation and ca 2.5% for alcohol ethoxylate sulfation. The molten sulfur is accurately measured and controlled by mass flow meters. The organic feedstock is also accurately controlled by mass flow meters and a variable speed-driven gear pump. The high velocity SO reaction gas and organic feedstock are introduced into the top of the sulfonation reactor,, in cocurrent downward flow where the reaction product and gas are separated in a cyclone separator, K, then pumped to a cooler, L, and circulated back into a quench cooling reservoir at the base of the reactor, unique to Chemithon concentric reactor systems. The gas stream from the cyclone separator, M, is sent to an electrostatic precipitator (ESP), N, which removes entrained acidic organics, and then sent to the packed tower, H, where SO2 and any SO traces are adsorbed in a dilute NaOH solution and finally vented, O. Even a 99% conversion of SO2 to SO contributes ca 500 ppm SO2 to the effluent gas. [Pg.89]

A significant advantage of immobilized enzymes is the total absence of catalytic activity in the product. Moreover, the degree of substrate-to-product conversion can be controlled during processing, eg, by adjusting the flow rate through a packed-bed column reactor of immobilized enzyme. [Pg.291]

Fig.2 shows the experimental results of Co(NH3)6 reduction, which is done in a stirred reactor at 80 °C and pH 4.1. It can be seen that activated carbon can promote the [Co(NH3)6] reduction significantly. The [Co(NH3)6] " conversion reaches 81.2% with6.7g/l activated carbon in the aqueous solution while only 8.18% of [Co(NH3)6] is reduced when there is no activated carbon added. Thus, a regeneration column packed with the activated carbon should be equipped with the absorber. [Pg.231]

In Fig. 1, a comparison can be observed for the prediction by the honeycomb reactor model developed with the parameters directly obtained from the kinetic study over the packed-bed flow reactor [6] and from the extruded honeycomb reactor for the 10 and 100 CPSI honeycomb reactors. The model with both parameters well describes the performance of both reactors although the parameters estimated from the honeycomb reactor more closely predict the experiment data than the parameters estimated from the kinetic study over the packed-bed reactor. The model with the parameters from the packed-bed reactor predicts slightly higher conversion of NO and lower emission of NHj as the reaction temperature decreases. The discrepancy also varies with respect to the reactor space velocity. [Pg.447]

In this study, Pt/AliOj having high activity for CO oxidation and different affinities for fee adsorption of CO and Hi was selected as a catalyst/adsorbent In a conventional packed bed reactor (PBR), fee surface of fee catalyst is dominantly covered by COads with small amotmt of Oads fee CO conversion is therefore low. Several investigations on periodic operation have illustrated feat fee reaction front wife comparable amount of fee two adsorbed species leads to enhancement of fee CO conversion. Conceptually, this type of the reaction front should be generated by application of a CMBR, as well. Figure 1 illustrates an image of... [Pg.805]


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