Membrane reactors overview

Mathematical modelling of membrane reactors overview of strategies and applications for the modelling of a hydrogen-selective membrane reactor... 

Rautenbach and MeUis [75] describe a process in which a UF-membrane fermentor and a subsequent NF-treatment of the UF-permeate are integrated. The retentate of the NF-step is recycled to the feed of the UF-membrane reactor (Fig. 13.8). This process has been commercialised by Wehrle-Werk AG as the Biomembrat -plus system [76] and is well suited for the treatment of effluents with recalcitrant components. The process also allows for an additional treatment process, like adsorption or chemical oxidation of the NF-retentate, before returning the NF-retentate to the feed of the UF-membrane fermentor. Usually, the efficiency of these treatment processes is increased as the NF-retentate contains higher concentrations of these components. Pilot tests with landfiU leachates [75] and wastewater from cotton textile and tannery industry have been reported [77]. An overview of chemical oxygen demand (COD) reduction and COD concentrations in the permeate are shown in... 

Porous ceramic membranes for catalytic reactors - overview and new ideas. Journal of Membrane Science, 181, 3-20. 

The present work will mainly focus on biochemical membrane reactors operate at the production scale and give an overview of systems of potential interest studied at the laboratory level. 

The choice of the catalyst is of large influence on the behaviour of the reforming process. Ni-based catalyst are most common, but recently more advanced catalysts have been developed as well. As indicated before, one of the advantages of a membrane reactor is that it can be operated at much lower temperatures but with the consequence that state-of-the-art catalysts might not be sufficiently active anymore. In this paragraph, an overview is provided on commonly used catalysts and some of the problems that may be encountered [7],... 

Introduction of a permselective membrane to a reactor zone opens up opportunities for resolving the above important reaction performance issues. An overview of this concept will be given next followed by some examples portraying the benefits of a membrane reactor. 

Julbe A, Farrussseng D, and Guizard C. Porous ceramic membranes for catalytic reactors—overview and new ideas. J. Membr. Sci. 2001 181 3-20. 

This chapter gives an overview of the synthesis procedures and appUcations of zeoUte membranes (gas separation, pervaporation, zeolite-membrane reactors), as well as new emerging appUcations in the micro- and nanotechnology field. Related areas such as new zeoUte and zeoUte-related materials for membranes, alternative supports, and scale-up issues are also discussed. 

More specifically in the area of this overview, zeolite materials constitute the main group of microporous membranes with regard to their potential membrane-reactor apphcations. The wide variety of existing zeolite structures, together with the possibility of modifying their adsorption and catalytic properties, provides us with a working material of high flexibihty. As a... 

The use of membrane reactors allows process conditions which cannot be obtained with more conventional processes (see Chapter 10 and overviews [13]) and which allow improved yields and selectivities, the use of two simultaneously occurring reactions (e.g. the main reaction and a decoking reaction to eliminate carbon deposits), controlled supply of reactant, etc. 

S. Ilias and R. Govind, Development of high temperature membranes for membrane reactor an overview. AIChE Symp. Ser., 85,268 (1989) 18. 

The porous ceramic membrane can be used to either separate biologically reacting material in reactors, or carry catalysts, microbes or enzymes to influence the desired reactions. An overview of the Japanese efforts for the establishment of membrane reactors in the "Aqua Renaissance 90 Project" are summarised by Kimura [95] a very recent review was written by Zaman and Chakma [96]. The preparation of microporous membranes (pore diameters smaller than 2 nm) for the application in membrane reactors is described by Keizer et al. [97] and Julbe et al. [98], however without detailing the membrane reactor itself. 

Fig. 4 Overview of the main applications of polymers in membrane reactors. (View this art in color at www.dekker.com.)...

An overview of the variables in the membrane reactor process is given in Fig. 12, and those equations, which are most relevant from an engineering point of view, are summarized in Box 1. The significance of most of the variables should appear from Fig. 13 and Box 1 immediately, - for a full explanation, the reader is referred to the appendix. 

Membrane-based reactive separation (otherwise also known as membrane reactor) processes, which constitute the subject matter of this book, are a special class of the broader field of membrane-based separation processes. In this introduction we will first provide a general and recent overview on membranes and membrane-based separation processes. The goal is to familiarize those of our readers, who are novice in the membrane field, with some of the basic concepts and definitions. A more complete description on this topic, including various aspects of membrane synthesis can be obtained from a number of comprehensive books and reviews that have already been published in this area [1.1, 1.2, 1.3,... 

To put recent developments in catalytic membrane reactors into perspective, providing some background for the reader who is not an expert in this area is necessary. Those for whom this is superfluous may wish to skip to Section 3. The present section provides a brief overview of well-established developments in... 

M.P. Rohde, D. Unruh, G. Schauh, Membrane application in Fischer—Tropsch synthesis reactors — overview of concepts, in International Conference on Gas—Fuel 05, Elsevier, Amsterdam, 2005. 

A concise overview of recycling modes for chiral catalysts, including enzymes, is given by Kragl et al. [15]. The technical aspects of the application of continuously operated chemical membrane reactors was covered by Woltinger et al. [16, 17]. 

Due to the availability of the mentioned overviews it is not the goal of this chapter to consider the whole field of membrane reactors. Rather, the discussion below will be focused on presenting simplified and more detailed mathematical models capable of describing the performance of membrane reactors. Although there are several studies available for analyzing the combination of reaction and membrane separation (e.g. Salomon et al., 2000 Struis and Stucki, 2001 Wielandet al., 2002 Patil etal., 2005 Rohde etal., 2005) there is a need to analyze in more detail specific features of membrane reactors. The focus of this chapter will be the development and application of simplified and also more detailed mathematical models for packed-bed membrane reactors in which certain reactants are dosed over the reactor wall using nonselective membranes. This type of membrane reactor is sometimes also-called a distributor (Dalmon, 1997 Julbe et al, 2001). Despite this restricted focus of the work, most of the concepts considered should be applicable also in the analysis of other types of membrane reactors. 

Porous Ceramic Membranes for Catalytic Reactors - Overview and New Ideas. Journal of Membrane Science,... 

Rohde, M.P., Unruh, D. and Schaub, G., 2005. Membrane Application in Fischer-Tropsch Synthesis Reactors - Overview of Concepts. Catalysis Today, 106(1-4) 143-148. 

Fig. 5.1 Schematic overview of the basic functions membranes can have in membrane reactors.

Based on a major division by membrane function in the reactor, a number of examples of membrane reactors are given below, illustrating the importance of the use of membranes for combining reaction and separation. Obviously, the list of membrane-based processes described here will not be exhaustive, although the following paragraphs will give an overview of the applications of membranes for chemical reactions. 

As a main scope, the present chapter will give an overview on the general classification of the membranes, paying particular attention to the palladium-based membranes and their applications, pointing out the most important benefits and the drawbacks due to their use. Finally, the application of palladium-based membranes in the area of the membrane reactors will be illustrated and such reaction processes in the issue of hydrogen production will be discussed. 

With reference to the book content, the authors divided it into 11 chapters. The book starts with an overview on membrane selective membranes integrated in the chemical reaction environment. The thermodynamics and kinetics of membrane reactors are also formulated and assessed for different membrane reactor architectures. 

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