Staged membrane reactors

Figure 9.6 Three-stage membrane reactor system in the HMR concept, after [27],...

Other reactor configurations and concepts have also been discussed in the technical literature. Most commonly dted are hybrid concepts, where the membrane reactor is used as an add-on stage to an already existing conventional reactor. This particular configuration has a number of attractive features, especially for applications involving conventional type porous membranes, which are characterized by moderate (Knudsen-type) permselective properties. Staged membrane reactors have received mention and so have reactors with multiple feed-ports and recycle. To facilitate the transport across the membrane in laboratory studies one often applies a sweep gas or a vacuum in the permeate side or a pressure gradient across the membrane. It is unlikely that the first two approaches, effective as they may be in laboratory applications, will find widespread commercial application. 

Due to these main reasons, new configurations called Staged Membrane Reactor (SMR) or Reformer and Membrane Modules (RMMs) have been proposed in the teehnieal literature [25-29]. 

Theoretical Study of Staged Membrane Reactor Performance... 

Caravella A, Di Maio FP, Di Renzo A (2010) Computational study of staged membrane reactor configurations for methane steam reforming. I. Optimization of stage lengths. AIChE J 56(l) 248-258... 

Staged membrane reactor configuration. Selective membrane is assembled in separation modules apphed downstream to reaction imits, and the plant is composed by a series of reaction-separation modules. 

Water-gas shift Staged membrane reactor 7% Chap. 7... 

Recently, the first membrane reactor pilot plant has been realized. A staged membrane reactor for natural gas steam reforming, also called reformer and membrane modules (RMM) test plant, having the capacity of 20 Nm /h of hydrogen, has been designed and constructed to investigate at an industrial scale level the performance of such innovative architecture. 

The major features and applieadon opportunities for integrated membrane reactor and staged membrane reactor configuration have been described in some details. We may conclude that membrane reactors actually show promises for conversion of equilibrium-limited reactions, selectivity toward some intermediates and improvement of energy efficiency. Consistent application of such technology... 

Figure 11.3 Scheme of the permeative-stage membrane reactor (PSMR) considered, after Caravella et al ... 

Membrane Reactor Technologies Ltd (MRT) has experimentally verified the permeative-stage membrane reactor concept. With the membranes outside the reaetor, operation at more favorable conditions for both reaction (750 °C) and membrane separation (450 °C or lower) is possible. A decrease in the metal cost of palladium-based membranes by 86.5% and membrane area by >70% to aehieve equal hydrogen production capacity was reported. The volume of reformer decreases accordingly, thus, the costs of both the reactor and membrane module are reduced. 

A reformer and membrane module system (RMM) (permeative-stage membrane reactor) with 20 N m h of hydrogen capacity has been designed... 

A. Caravella, F. P. Di Maio and A. Di Renzo, Optimization of membrane area and catalyst distribution in a permeative-stage membrane reactor for methane steam reforming, J. Membr. Sci., 2008, 321, 209-221. 

Another method for integrating a selective membranes in a chemical process is to place them outside the reactor, in proper units located downstream. Figure 13.7 shows a staged membrane reactor (SMR) composed of two-step reaction-separation units. 

Two membrane reactor configurations, the staged membrane reactor (SMR) and the integrated membrane reactor (IMR), are presented and compared, with the following main outcomes ... 

Staged membrane reactor (SMR) or reactor and membrane module (RMM), where the selective membrane is placed outside the reactor, in a proper unit located downstream (Fig. 12.2). 

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