Inorganic membrane reactors characteristics

V. T. Zaspalis, A. J. Burggraaf, Inorganic membrane reactors to enhance the productivity of chemical processes, in Inorganic membranes synthesis, characteristics and applications,... 

V.T. Zaspalis and A.J. Burggraaf, Inorganic membrane reactors to enhcmce the productivity of processes, in R.R. Bhave (Ed.), Inorganic Membranes Synthesis, Characteristics and Applications. Reinhold, New York, 1991, Ch. 7. 

Zaspalis, V.T.. and Burggraaf, A.J., Inorganic Membmae Reactors to Enhance Productivity of Chemical Processes, in Inorganic Membranes, Synthesis, Characteristics and Applications, Bhave, R.R (Ed.), Van Nostrand Reinhold, New York, 1991,... 

Zaspalis and Burggraaf [47] have summarized typical membrane reactor configurations, different membrane/ catalyst combinations, and a large number of membrane reactor studies. Their article clearly shows that inorganic membranes prepared by the sol-gel method, with their dual ability in catalysis and separation, have many unique advantages over other product forms. At the same time, it is important to realize that the parameters which affect a membrane s characteristics and the advantages which the sol-gel process offers are similar to what has been presented thus far. 

Different membrane shapes are used, such as plates, foils, spirals, hollow fibers, tubes, and even monilithic multichannel elements have been mentioned in the context of membrane reactors. In the following section, a general survey will be given indicating the main characteristics of the different types of inorganic membranes used in CMRs. More details can be found elsewhere [13-15]. 

Because of the unique characteristics of inorganic membranes mentioned above, the search for inorganic membranes of practical significance has been continuing for several decades. With the advent of ceramic membranes with superior stabilities coming to the separation markets, the potentials for inorganic membranes as separators and/or reactors are being explored at an accelerated rate never wimessed before. 

The preparation and fabrication methods and their conditions described in Chapter 3 dictate the general characteristics of the membranes produced which, in turn, affect their performance as separators or reactors. Physical, chemical and surface properties of inorganic membranes will be described in detail without going into discussions on specific applications which will be treated in later chapters. Therefore, much of this chapter is devoted to characterization techniques and the general characteristics data that they generate. 

Opposiny-reactants mode. When immobilized with a catalyst or enzyme, the interconnected tortuous pores or the nearly straight pores of a symmetric inorganic membrane provides a relatively well controlled catalytic zone or path for the reactants in comparison with the pellets or beads in a fixed or fluidized bed of catalyst particles. This unique characteristic of a symmetric membrane, in principle, allows a novel reactor to be realized provided the reaction is sufficiently fast. The concept applies to both equilibrium and irreversible reactions and does not utilize the membrane as a separator. Consider a reaction involving two reactants, A and B ... 

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