Conventional catalytic reactor

Figure 7. Rate of Nj fonnation over Sr/LajO, in a conventional catalytic reactor with the following reagent gases , O 1% NO A, 1% NO -t- 0.25% CH4 , 1% NO + 0.25% CH4 + 0.5% Oj. The total pressure was 760 Torr.

Catalytic reactivity results (H202 productivity and selectivity) summarized in Figure 8.9 are comparable, taking into account the differences in the reaction conditions, with patented results reported in Table 8.3. Although, for the direct synthesis of H202, the costs of membrane operations are still higher than those of conventional catalytic reactors, the possibility of safer operations is an incentive, particularly for smaller scale applications. 

Thus, activity and kinetics data and activation energy values measured with such a spectroscopic cell have to be consistent with those obtained with corresponding conventional catalytic reactors. 

When the values shown in Table 2 are used to calculate the overall molar production rates per unit volume of reactor for monolith reactors, values of 40 mol/mreactor s are foimd. Figure 14 illustrates that this value is very high in comparison with those foimd in conventional catalytic reactors used in industry. 

Current and future advancements in materials engineering might, however, lead to a significant reversal of this trend, and in this context the lowering of operating temperatures represents the main target. By comparison, compared to conventional catalytic reactors, SEMRs could be used to produce expensive fine chemicals, with attractive yields. 

Investigations carried out on membrane reactors based on pure oxide ion-conducting membranes have been reviewed [12]. Compared to the M lEC-membrane reactor, SEMRs allow for direct control of the oxygen permeation rate due to the faradaic coupling of oxygen flux and cell current. The SEMR has advantages over conventional catalytic reactors [3, 5], including ... 

Electrochemical reactors are heterogeneous by their very nature. They always involve a solid electrode, a liquid electrolyte, and an evolving gas at an electrode. Electrodes come in many forms, from large-sized plates fixed in the cell to fluidizable shapes and sizes. Further, the total reaction system consists of a reaction (or a set of reactions) at one electrode and another reaction (or set of reactions) at the other electrode. The two reactions (or sets of reactions) are necessary to complete the electrical circuit. Thus, although these reactors can, in principle, be treated in the same manner as conventional catalytic reactors, detailed analysis of their behavior is considerably more complex. We adopt the same classification for these reactors as for conventional reactors, batch, plug-flow, mixed-flow (continuous stirred tank), and their extensions. 

Recently, a conceptual design-based simulation methodology has been developed for the comparative economic assessment of membrane reactors with conventional catalytic reactors [388]. A basic assumption to the simulation smdy is that the chosen membranes do possess durability and performance characteristics as desired for industrial-scale processing. For the two illustrative dehydrogenation reaction schemes, the cost contribution of membranes and other auxiliary equipment is estimated not to exceed 20% of the total costs. Besides variable and fixed costs in processes, environmental impacts (energy and material inputs, efficiency and environmental releases) associated with manufacturing. 

In this chapter, the most popular approaches for hydrogen production from H2S are reviewed before a novel open reactor architecture (OA) is presented, where the coupling of reaction and hydrogen separation is achieved in the series of consecutive conventional catalytic reactors (CR), each followed by a membrane separator (MS). Experimental study on the development of a suitable H2S decomposition catalyst is also presented, and the theoretical calculations for one... 

Structured catalysts may be used to overcome the drawbacks of conventional catalytic reactors [3]. These are reactors with monohthic converters, with catalyst-coated static mixers and arranged packings as applied in distillation and absorption columns. 

The generated potential via exergonic reactions in direct fuel cells is partly used to promote electrode reactions (kinetic overpotential), while in indirect fuel cells, the fuel is first processed into simpler fuels (to reduce the kinetic overpotential) via conventional catalytic reactors, or CMRs, in which temperature is used as the key operating parameter to accomplish the desired kinetics and equilibrium conversions. Among the direct fuel cells, e.g., PEMFCs use hydrogen, direct methanol fuel cell (DMFC) uses methanol, while the SOFC can operate directly on natoral gas (Figiue 15.3). However, in indirect fuel cells, a complex fuel must be suitably reformed into simpler molecules such as H2 and CO before it can be used in a fuel ceU. 

Figure 16.22 Changes in conversion and yields of ethylbenzene, toluene and benzene along the conventional catalytic reactor (CCR).

Figure 16.24 Comparison of conversion changes between in membrane reactor (MR) and in conventional catalytic reactor (CCR) at a large weight hourly space velocity (WHSV).

The pressure of gas was 101.325 kPa. The ammonia synthesis rate was stable after passage of current for 2-6 min and this rate was at least three magnitudes higher than that of conventional catalytic reactor. The conversion of hydrogen was close to 100% which eliminated thermodynamic equilibrium limitation. The main problem of this method is that the conductivity of SCY ceramic is very poor at normal temperature. Even at 570°C, its conductivity is unsatisfied because the current density was smaller than 2 mA-cm and could not be further increased. This limited the efficiency of ammonia synthesis and theoretical research. The use of solid electrolyte with high proton conductivity at low temperature to replace the SCY ceramic may be favorable to decreasing the synthesis temperature and increasing the current density and production efficiency. 

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