Planar Membrane Reactors

Since the syngas passes over multiple stacks arranged in series, it is only partially converted over each stack and temperature and composition control can be more easily achieved. This is similar to the design intent of the Linde reactor 

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It is evident that in many situations the reaction rate will be directly proportional to the surface area between phases whenever mass transfer hmits reaction rates. In some situations we provide a fixed area by using solid particles of a given size or by membrane reactors in which a fixed wall separates phases Ifom each other. Here we distinguish planar walls and parallel sheets of sohd membranes, tubes and tube bundles, and spherical solid or liquid membranes. These are three-, two-, and one-dimensional phase boundaries, respectively. 

It is important to attain as high an area as possible for a membrane reactor. Configurations with multilayer planar membranes, coiled membranes, or as multiple tubes also can be used for similar processes with potentially very high surface areas, as sketched in Figure 12-6. 

In the membrane reactor a wall of area separates the phases, and this area is generally fixed by the geometry of the reactor using planar or cylindrical membranes. However, most multiphase reactors do not have fixed boundaries separating phases, but rather allow the boundary between phases to be the interfacial area between insoluble phases. This is commonly a variable-area boundary whose area wiU depend on flow conditions of the phases, as shown in Figure 12-7. 

Installation of the PDU system was completed, and the PDU reactor system and PDU membrane modules were commissioned at high temperature and pressure with a s mgas mixture. The PDU integrates the various components of the ITM Syngas/ITM H2 reactor design and will be used to confirm the performance of the planar membrane modules and seals under commercial process conditions. The PDU reactor is shown in Figure 4. 

Figure 8.13 Cross-section of a conceptual syngas reactor for planar membranes showing the stacks of planar membranes (top), air feed manifolding to the stacks (middle) and the nonpermeate exit manifolding (bottom).

Figure 8.14 Figure 5 from U.S. Patent Application 20050031531 A1 [27] showing a longitudinal cross-section ofa reactor for planar membranes, and showingthe stacks of membranes (501, 503, etc), the reactant feed (517),the syngas product (557), the fresh air feed (553), the nonpermeate (555) exhaust (555). 

Diethehn S., Sfeir J., Clemens F., Van herle J., Favrat D., Planar and tubular perovskite-type membrane reactors for the partial oxidation of methane to syngas , J Solid State Electrochem (8) (2004)611-617. 

Dolan MD, Donelson R, Dave NC, 2010. Performance and economics of a Pd-based planar WGS membrane reactor for coal gasification. International Journal of Hydrogen Energy, 35,10994-11003. 

Figure 33.7 Reactor configuration and Pd-based planar membrane details used by the Grace group. (Reprinted with permission from Ref. [27]. Copyright 2011, American Chemical Society.)...

Figure 7.4 shows the structure of an FBMR with plate-type Pd-Ag dense metal membranes for hydrogen production [8, 9]. Two-sided planar membrane panels are suspended vertically in the reactor. Each side of the panels consists of 25 pm thick Pd-Ag foil mounted on a porous stainless steel base with a barrier layer to prevent interdiffusion... 

In this chapter, we first give an overview of carbon membrane materials (Section 10.2) and the classification of carbon membranes (Section 10.3). Then, unsupported carbon membranes, based on planar membranes and asymmetric hollow fiber membranes are discussed (Section 10.4). In Section 10.5, the supported CMSMs are reviewed in detail in terms of precursors, supports, fabrications and problems. In Section 10.6, carbon-based membrane reactors are discussed in detail, based on the topics of dehydrogenation reactions, hydration reactions, hydrogen production reactions, H2O2 synthesis, bio-diesel synthesis, and new carbon membranes for carbon membrane reactors (CMRs). In the end, the new concept of using carbon membranes in microscale devices (microcarbon-based membrane reactor) is outlined (Section 10.7). 

One way to ease any difficulties that may arise in fabricating a membrane, especially in design configurations that are not planar, is to go membraneless. Recent reports take advantage of the laminar flow innate to microfluidic reactors ° to develop membraneless fuel cells. The potential of the fuel cell is established at the boundary between parallel (channel) flows of the two fluids customarily compartmentalized in the fuel cell as fuel (anolyte) and oxidant (catholyte). Adapting prior redox fuel cell chemistry using a catholyte of V /V and an anolyte of Ferrigno et al. obtained 35 mA cmr at... 

Figure 1. (a) Integrated planar photoelectrode for H2 production (b) Conceptual design of large-scale reactor (c) Photoelectrode installed in collection tubes with separating membrane... 

The two most common membrane geometries are the flat plate and the tube. Single flat plate membranes are usually used in laboratory scale investigations due to their ease of fabrication. Tubular membranes are more and more popular due to their much larger ratio of the membrane surface area to the equipment volume than flat plate membranes [4]. OITM reactor configurations with multi-planar or multi-tubular structures are required for commercial use. 

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