Oxidation membrane reactors for

Novel Oxidative Membrane Reactor for Dehydrogenation Reactions Experimental Investigation... 

Figure 2.12. A schematic of the solid oxide membrane reactor for synthesis gas production. From Dyer et al. [2.232], with permission from Elsevier Science.

Fig. 4. Configuration of a ceramic membrane reactor for partial oxidation of methane. The membrane tube, with an outside diameter of about 6.5 mm and a length of up to about 30 cm and a wall thickness of 0.25-1.20 mm, was prepared from an electronic/ionic conductor powder (Sr-Fe-Co-O) by a plastic extrusion technique. The quartz reactor supports the ceramic membrane tube through hot Pyrex seals. A Rh-containing reforming catalyst was located adjacent to the tube (57).

Fig. 6. Configuration of a ceramic membrane reactor for partial oxidation of methane. The membrane disk was prepared by pressing Bao.5Sro.5Coo.8Feo.2O3-s oxide powder in a stainless steel module (17 mm inside diameter) under a pressure of (1.3-1.9) X 109 Pa. The effective area of the membrane disk exposed to the feed gas (CH4) was 1.0 cm2 (72).

The viability of one particular use of a membrane reactor for partial oxidation reactions has been studied through mathematical modeling. The partial oxidation of methane has been used as a model selective oxidation reaction, where the intermediate product is much more reactive than the reactant. Kinetic data for V205/Si02 catalysts for methane partial oxidation are available in the literature and have been used in the modeling. Values have been selected for the other key parameters which appear in the dimensionless form of the reactor design equations based upon the physical properties of commercially available membrane materials. This parametric study has identified which parameters are most important, and what the values of these parameters must be to realize a performance enhancement over a plug-flow reactor. 

Figure 1. A schematic representation of a membrane reactor for improving yields of intermediate products in a partial oxidation reaction.

The highest space-time yield (120 g 1. 1 d 1) was achieved in a continuously operated enzyme membrane reactor for the chloroperoxidase-catalyzed oxidation of indole to oxindole with H202 in aqueous t-BuOH, whereas a fed-batch reactor obtained the highest total turnover number (TTN 860 000) (Seelbach, 1997). 

Kurungot et al. [48] developed a novel membrane material and a catalytic membrane reactor for the partial oxidation of methane. The driver of the development was the fact that rates of reforming reactions are much higher compared with the low permeability of conventional palladium membranes [49], Silica was previously recognized as a low-cost alternative to palladium [50], Additionally, the conventional... 

Y. Ye, L. Rikho-Struckmann, B. Munder, et al., Feasibility of an electro-chemical membrane reactor for partial oxidation of n-butane to maleic anhydride. 

Although the use of membrane reactors for the retention of the enzyme is mostly applied in continuous processes, some authors used a membrane batch reactor in order to reuse the enzyme in consecutive cycles [11, 74]. Flock et al. used a membrane unit coupled to the reactor with recycling of both permeate and retentate streams to the reactor vessel. A valve at the outlet of the membrane maintained pressure within the range fixed by the manufacturer [74]. Pasta et al. operated a reactor with the membrane inside, emptied the reactor content at scheduled times, and thereafter, replenished it with fresh solution of the substrate and the oxidizing system [11]. 

Watercatox Not an established process, but a project of the Fifth Framework Program of the European Union. The purpose was to develop catalytic processes for destroying organic residues in water by wet air oxidation ( WAO).The chosen system used a tubular catalytic membrane reactor for contacting the aqueous solution with air. Several companies and research institutes participated in this project from 2000, and the process was piloted with several real industrial liquid effluents. 

Alonso et al. (248,249) also attempted to use a membrane reactor for n-butane oxidation. The operation of the membrane reactor was compared with that of a conventional fixed bed. Initially, Alonso et al. used an external bed of sand, fluidized with oxygen and heated with steam, such that the reactor temperature was maintained essentially constant (248). O2 and butane flowed concurrently through the reactor, through the shell and tube sides (containing catalyst), respectively. However, as the authors noted, the MA yield was not on par with that observed with the fixed-bed reactor at lower butane concentrations. Potentially, production... 

The use of a membrane reactor for shifting equilibrium controlled dehydrogenation reactions results in increased conversion, lower reaction temperatures and fewer byproducts. Results will be presented on a palladium membrane reactor system for dehydrogenation of 1-butene to butadiene, with oxidation of permeating hydrogen to water on the permeation side. The heat released by the exothermic oxidation reaction is utilized for the endothermic dehydrogenation reaction. 

However, the addition of an oxidant such as oxygen is not without some trade-off. To help solve the problem of catalyst deactivation due to carbon deposit in an alumina membrane reactor for dehydrogenation of butane, oxygen is introduced to the sweep gas, helium, on the permeate side at a concentration of 8% by volume. The catalyst service life increa.scs from one to four or five hours, but the selectivity to butene decreases from 60 to 40% at 480 C [Zaspalis et al., 1991b]. If oxygen is added to the feed stream entering the membrane reactor in order to inhibit coke formation, the butene selectivity decreases even more down to 5%. 

Lafaiga D., Santamaria J. and Menendez M., Methane oxidative coupling using porous ceramic membrane reactors. Part I. Reactor development, Chem. Eng. ScL 49 2005 (1994). Sloot H.J., Smolders C.A., van Swaaij W.P.M. and Versteeg G.F., High-temperature membrane reactor for catalytic gas-solid reactions, AIChE J. J5 887 (1992). 

Peureux J., Torres M., Mozzanega H., Giroir-Fendler A., and Dalmon J.A., Nitrobenzene liquid-phase hydrogenation in a membrane reactor. Catalysis Today 25 409 (1995). Chanaud P., Julbe A., Larbot A., Guizard C., Cot L., Borges H., Giroir-Fendler A. and Mirodatos C., Catalytic membrane reactor for oxidative coupling of methane. Part 1 Preparation and characterization of LaOCl membranes. Catalysis Today 25 225 (1995). 

Mota S, Micahon S, Volta JC, and Dalmon JA. Membrane reactor for selective oxidation of butane to maleic anhydride. Catal Today 2001 67 169-176. 

P. Chanaud, A. Julbe, A. Larbot, C. Guizard, L. Cot, H. Borges, A. Giroir Fendler, C. Mirodatos, Catalytic membrane reactor for oxidative coupling of methane. Part 1 preparation and characterisation of LAOCl membranes. Catal. Today, 25 (1995) 225. 

C.-Y. Tsai, Y.H. Ma, W.R. Moser and A.G. Dixon, Simulation of nonisothermal catalytic membrane reactor for methane partial oxidation to syngas, in Y.H. Ma (Ed.), Proceedings of the 3rd International Conference on Inorganic Membranes, Worcester, 1994, pp. 271-280. 

H. Borges, A.G. Fendler, C. Mirodatos, P. Chanaud and A. Julbe, Catalytic membrane reactor for the oxidative coupling of methane. Part 2 Catalytic properties of LaOCl membranes. Paper presented at the the 1st International Workshop on Catalytic Membranes, September 1994, Lyon-Villeurbanne, France. 

Today, the majority of research investigations into CMRs are being conducted by many institutions, in addition to oil and chemical and utilities companies [5]. The use of mixed ionic-electronic membrane reactors for the partial oxidation of natural gas is undergoing active development by a number of consortia based around Air Products and Chemicals (USA), Praxair (USA), and/or Air Liquide (France). At present, the development of CMRs involving a pure ion-conducting electrolyte is restricted to a few reports of conceptual systems [12, 95]. 

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