Power membrane reactors

Edlund, D., A Membrane Reactor for H2S Decomposition, Proceedings of the U.S. DOE Advanced Coal Fired Power Systems Review Meeting, Morgantown, WV, July 1996. 

J.W. Dijkstra, Y.C. van Delft, D. Jansen, P.P.A.C. Pex, Development of a hydrogen membrane reactor for power production with pre-combustion decarbonisation, Proceedings of the 8th International... 

Fuel cells and batteries are examples of membrane reactors in which a conducting membrane separates the anode and cathode compartments, which supply fuel and oxidant, respectively. With fuel cells we have the added complexity that we need an ion-conducting electrode, which is also a catalyst at each electrode so that we can extract electrical power from the energy of the reaction. A battery is similar to a fuel ceU except that now the fuel and oxidant are stored and supplied within the ceU rather than being supphed externally. A fuel cell is usually operated as a continuous-flow reactor, while a battery is a rechargeable batch reactor. 

Initial preparative work with oxynitrilases in neutral aqueous solution [517, 518] was hampered by the fact that under these reaction conditions the enzymatic addition has to compete with a spontaneous chemical reaction which limits enantioselectivity. Major improvements in optical purity of cyanohydrins were achieved by conducting the addition under acidic conditions to suppress the uncatalyzed side reaction [519], or by switching to a water immiscible organic solvent as the reaction medium [520], preferably diisopropyl ether. For the latter case, the enzymes are readily immobilized by physical adsorption onto cellulose. A continuous process has been developed for chiral cyanohydrin synthesis using an enzyme membrane reactor [61]. Acetone cyanhydrin can replace the highly toxic hydrocyanic acid as the cyanide source [521], Inexpensive defatted almond meal has been found to be a convenient substitute for the purified (R)-oxynitrilase without sacrificing enantioselectivity [522-524], Similarly, lyophilized and powered Sorghum bicolor shoots have been successfully tested as an alternative source for the purified (S)-oxynitrilase [525],... 

Barbieri, G., Brunetti, A., Tricoli, G. and Drioli, E. (2008) An innovative configuration of a Pd-based membrane reactor for the production of pure hydrogen. Experimental analysis of water gas shift. Journal of Power Sources, 182 (1), 160-167, http //dx.doi.org/10.1016/ j.jpowsour.2008.03.086. 

At first sight, adsorption and reaction are well-matched functionalities for integrated chemical processes. Their compatibility extends over a wide temperature range, and their respective kinetics are usually rapid enough so as not to constrain either process, whereas the permeation rate in membrane reactors commonly lags behind that of the catalytic reaction [9]. The phase slippage observed in extractive processes [10], for example, is absent and the choice of the adsorbent offers a powerful degree of freedom in the selective manipulation of concentration profiles that lies at the heart of all multifunctional reactor operation [11]. Furthermore, in contrast to reactive distillation, the effective independence of concentration and temperature profiles... 

Stoukides M, (2000). Solid electrolyte membrane reactors current experience and future outlook. Catalysis Reviews Science Engineering, 42 1-70 Sun C, Stimming U, (2007). Recent anode advances in solid oxide fuel cells. Journal of Power Sources 171 247-260... 

For ease of fabrication and modular construction, tubular reactors are widely used in continuous processes in the chemical processing industry. Therefore, shell-and-tube membrane reactors will be adopted as the basic model geometry in this chapter. In real production situations, however, more complex geometries and flow configurations are encountered which may require three-dimensional numerical simulation of the complicated physicochemical hydrodynamics. With the advent of more powerful computers and more efficient computational fluid dynamics (CFD) codes, the solution to these complicated problems starts to become feasible. This is particularly true in view of the ongoing intensified interest in parallel computing as applied to CFD. 

In the membrane reactor many parameters influence the performance of the system. By making the model equations (mass balances) dimensionless [61], parameters are grouped so that a few dimensionless groups appear which describe the process. The physical meaning and their definitions are given in Table 14.2. A kinetic expression of the power law type for the reaction rate is assumed. 

For a power plant including a membrane reactor with membranes with a selectivity of 15 the efficiency of the total system has been determined through flow sheet calculations. In these calculations the requirements and the demands of the membrane reactor and the rest of the system must match, so one or more iterative calculations is necessary to optimise the total system. The results of the calculations after optimisation are presented in Table 14.11 in which three... 

Through membrane reactor model calculations it has been shown that membranes can enhance the conversion of a WGS membrane reactor and concurrently separate hydrogen from carbon dioxide. This system can be used to control the release of CO2 to the atmosphere from a IGCC power plant. Through process... 

The same group [2.354] has also recently reported on the performance of a membrane reactor with separate feed of reactants for the catalytic combustion of methane. In this membrane reactor methane and air streams are fed at opposite sides of a Pt/y-A Os-activated porous membrane, which also acts as catalyst for their reaction. In their study Neomagus et al. [2.354] assessed the effect of a number of operating parameters (temperature, methane feed concentration, pressure difference applied over the membrane, type and amount of catalyst, time of operation) on the attainable conversion and possible slip of unconverted methane to the air-feed side. The maximum specific heat power load, which could be attained with the most active membrane, in the absence of methane slip, was approximately 15 kW m with virtually no NO emissions. These authors report that this performance will likely be exceeded with a properly designed membrane, tailored for the purpose of energy production. 

Kajiwara M, Uemiya S, Kojima T. Stability and hydrogen permeation behavior of supported platinum membrtmes in presence of hydrogen sulfide. Int J Hydrogen Energy. 1999 24 839. Edlund D. A membrane reactor for H2S decomposition. Advanced coal-fired power systems. Bend Bend Research, Inc 1996. 

Edlund D. A membrane reactor for H2S decomposition. Advanced Coal-Fired Power Systems 96 Review Meeting, 1996, Morgantown, WV. 

A conventional FPS, shown in Fig. 14.2, includes a reformer, two WGS reactors, and two Preferential Oxidation (PrOx) reactors, located downstream of the WGS. For PEM fuel cells, it is a necessity to assure < 10 ppm of CO in the cell stack. These reactors form a considerable fraction of the FPS weight, volume, and cost. Replacing this train by an integrated hydrogen permeation selective membrane on the water gas shift reactor, shown in Fig. 14.3, results in a considerable reduction in the number of components, cost, and volume of the FPS. This will make fuel cell power plants practical and affordable for power generation in a wide range of applications, especially for residential and transportation. Numerous published works [8, 9] in the area of catalytic membrane reactors can be quoted in the experimental [10] and numerical [11, 12] domains. 

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