Membrane Reactor Technologies

Among the wide choice of reactor designs, the biofilm reactor is one of the best suited for azo-dye conversion as it meets two important process requisites. The first is related to the hindered growth feature of bacterial metabolism under anaerobic conditions. The second is related to the necessity to increase cell densities (see previous section) with respect to those commonly harvested in liquid broths [55, 56]. Except for bacteria that forms aggregates spontaneously, immobilization of cells on granular carriers and membrane reactor technology are the two common pathways to achieve high-density confined cell cultures in either discontinuous or flow reactors. 

Nourbakhsh, N., A. Champagnie, T. T. Tsotsis and 1. A. Webster. 1989. Transport and reaction studies using ceramic membranes. In A.I.Ch.E. Symp. Scr. Membrane Reactor Technology, eds. R. Govind and N. Itoh, pp. 75-84. New York Am. Institute of Chem. Engr. 

The acylase-catalyzed resolution of N-acetyl-D,L-amino acids to obtain enantiomerically pure i-amino acids (see Chapter 7, Section 7.2.1) has been scaled up to the multi-hundred ton level. For the immobilized-enzyme reactor (Takeda, 1969) as well as the enzyme membrane reactor technology (Degussa, 1980) the acylase process was the first to be scaled up to industrial levels. Commercially acylase has broad substrate specificity and sufficient stability during both storage and operation. The process is fully developed and allowed major market penetration for its products, mainly pharmaceutical-grade L-methionine and L-valine. 

X. Shao, Y. Fend, S. Hu and R. Govind, Pectin Degradation in a Spiral Membrane Reactor, in Membrane Reactor Technology, R. Govind and N. Itoh (eds), AIChE Symposium Series Number 268, AIChE, New York, NY, Vol. 85, pp. 85-92 (1989). 

The inorganic membrane reactor technology is in a state characterized by very few in practice but many of promise. Since the potential payoff of this technology is enormous, it deserves a close-up look. This and the following three chapters are, therefore, devoted to the review and summary of the various aspects of inorganic membrane reactors applications, material, catalytic and engineering issues. 

While the aforementioned and other novel membrane reactors hold great promises, many material, catalysis and engineering issues need to be fully addressed before the inorganic membrane reactor technology can be implemented in an industrial scale. This is particularly true for many bulk-processing applications at high temperatures and often harsh chemical environments. Those issues will be treated in the subsequent chapters. 

Detailed modeling of the transport and reaction steps in membrane reactors is beyond the scope of this text but can be found in Membrane Reactor Technology. The salient features, however, can be illustrated by the following example. When analyzing membrane reactors, it is much more convenient to use molar flow rates rather than conversion. 

Membrane Reactor Technologies NG Steam reforming hydrogen generator Transportation Commercial... 

The principle of the enzyme membrane reactor technology (developed in a collaboration between Degussa AG and Professor Wandrey s group at the Research Institute Jiilich, and in operation since 1980), and thus the principle of the Chemzyme membrane reactor, is depicted in Figure 1. 

Membrane reactor technology is certainly a promising process intensification solution which should lead to crucial benefits toward a more efficient steam reforming process conduction. 

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. 

C. S. Patil, PhD Thesis, University of Twente, Membrane Reactor Technology for Ultrapure Hydrogen Production, 2005. 

The case studies analysis, which focused on hydrogen production processes, demonstrates the potential of membrane reactor technology in terms of improving performance and reducing operating temperature, even if some crucial obstacles have yet to be overcome, as developing a reliable fabrication method and reducing membrane costs. 

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