Dense ceramic membranes for membrane reactors

Tianjin Polytechnic University, China and K. LI, Imperial College London, UK [Pg.271]

Abstract Dense ceramic membrane reactors are made from composite oxides, usually having perovskite or fluorite structure with appreciable mixed ionic (oxygen ion and/or proton) and electronic conductivity. They combine the oxygen or hydrogen separation process with the catalytic reactions into a single step at elevated temperatures ( 700°C), leading to significantly improved yields, simplified production processes and reduced capital costs. This chapter mainly describes the principles of various types of dense ceramic membrane reactors, and the fabrication of the membranes and membrane reactors. [Pg.271]

Key words membrane reactors, mixed ionic-electronic conductors (MIECs), perovskite, oxygen permeable membrane, proton conducting membrane. [Pg.271]

Dense ceramic membranes are made from composite oxides usually having perovskite or fluorite crystalline structure (Bouwmeester, 2003 Liu [Pg.271]

1 Principle of membrane reactor to promote reactions (a) selective permeation of by-product of an equilibrium-limited reaction (b) selective permeation of an intermediate product (c) dosing a reactant through the membrane and (d) supplying a well-defined reaction interface. In (a) and (b) the membrane functions as a product extractor, and as a reactant distributor in (c). (In the figure, A and B stand for two different reactants, C for a by-product, P for the desired product and nB for n mole of the reactant B.) [Pg.272]

Tan, X. and Li, K. (2013) Dense ceramic membranes for membrane reactors, in Handbook of Membrane Reactors, Volume I - Fundamental Materials Science, Design and Optimisation (ed A. Basile), Woodhead Publishing Limited, Cambridge, pp. 271-297. [Pg.26]

Applications of dense ceramic membrane reactors in selected oxidation and dehydrogenation processes for chemical... [Pg.347]

Compared to traditional processes, the dense ceramic membrane reactor possesses the following potential advantages (1) it is possible to provide oxygen for the reaction system in a more controllable manner and to... [Pg.349]

Schematic diagram for possible reaction pathways of the POM in a dense ceramic membrane reactor. [Pg.351]

Table 8.4 Dense ceramic membrane reactors for the decomposition reactions... [Pg.365]

It is well known that dense ceramic membranes made of the mixture of ionic and electron conductors are permeable to oxygen at elevated temperatures. For example, perovskite-type oxides (e.g., La-Sr-Fe-Co, Sr-Fe-Co, and Ba-Sr-Co-Fe-based mixed oxide systems) are good oxygen-permeable ceramics. Figure 2.11 depicts a conceptual design of an oxygen membrane reactor equipped with an OPM. A detail of the ceramic membrane wall... [Pg.53]

Ceramic electrochemical reactors are currently undergoing intense investigation, the aim being not only to generate electricity but also to produce chemicals. Typically, ceramic dense membranes are either pure ionic (solid electrolyte SE) conductors or mixed ionic-electronic conductors (MIECs). In this chapter we review the developments of cells that involve a dense solid electrolyte (oxide-ion or proton conductor), where the electrical transfer of matter requires an external circuitry. When a dense ceramic membrane exhibits a mixed ionic-electronic conduction, the driving force for mass transport is a differential partial pressure applied across the membrane (this point is not considered in this chapter, although relevant information is available in specific reviews). [Pg.397]

The general behavior of product-removal membrane reactors has been well studied. More details on porous ceramic membrane reactors can be found in the series of publications by Mohan and Govind. An analysis of different flow configurations and the limits of each has been provided for dense Pd membrane reactors by Itoh. ... [Pg.47]

Table 27.2. Membrane reactors using dense ceramic membranes for hydrogen production.

Dense ceramic membranes allow oxygen separation with extremely high selectivity and can be incorporated into membrane reactors for a variety of oxygen-related reactions. The applications of dense ceramic MRs will bring many economic and environmental benefits, with improved selectivity and yields. However, in order to realize the potential benefits of MRs and commercialize them successfully, there are still many challenges that have to be faced not only from membrane materials but also from engineering aspects. [Pg.176]

As described above, dense ceramic membranes are made of composite oxides with a large number of oxygen vacancies in the crystaUine lattice. Such materials are inherently catalytic to the oxidation and dehydrogenation reactions. Therefore, dense ceramic membrane may serve as both catalyst and separator, and catalyst is not required in the membrane reactor. As shown in Fig. 7.5a, the lattice oxygen directly takes part in the chemical reactions. Since the chemical reactions take place on the membrane surface, it is required to have a very porous membrane surface so as to contain a sufficient quantity of active sites. This can be achieved in the membrane preparation process, or by coating a porous membrane material after the preparation. The main potential problems for this are that the membrane may not have sufficient catalytic activity, and the catalytic selectivity cannot be modulated with respect to the considered reactions. [Pg.286]