Catalysts membranes

Reactor 10 [R 10] Catalyst Membrane Si-chip Micro Reactor with Sensing and Heating Functions... 

Figure 3.16 Schematic of Si-chip catalyst membrane micro reactor. Top view (A), end-on cross section of reaction channel (B) side-view cross section of reaction channel (C) [60].

Figure 3.17 Microfabrication sequence for the silicon component of the catalyst membrane micro reactor [57],...

PEFCs are an attractive alternative power source for mobile and stationary applications characterized by low emissions, good energy conversion efficiency and high power density. One of the main obstacles towards the commercialization of this technology is the high cost of component materials (catalyst, membrane, etc.) [160-162]. 

There has been an accelerated interest in polymer electrolyte fuel cells within the last few years, which has led to improvements in both cost and performance. Development has reached the point where motive power applications appear achievable at an acceptable cost for commercial markets. Noticeable accomplishments in the technology, which have been published, have been made at Ballard Power Systems. PEFC operation at ambient pressure has been validated for over 25,000 hours with a six-cell stack without forced air flow, humidification, or active cooling (17). Complete fuel cell systems have been demonstrated for a number of transportation applications including public transit buses and passenger automobiles. Recent development has focused on cost reduction and high volume manufacture for the catalyst, membranes, and bipolar plates. 

M., Mukai, S.R., Kawase, M., and Hashimoto, K. (2003) Methanol to olefins using ZSM-5 zeolite catalyst membrane reactor. Chem. Eng. Sci.,... 

The National Technical University of Athens (NTUA) works on hydrogen production from waste gases, production of hydrogen from solid fuels, water-gas-shift reaction catalysts, membrane separation, gasification of solid fuels, simulation of advanced power systems based on fuel cells, and hydrogen production and infrastructure. 

In the future, it is likely that reactive comminution will be used as a tool for the preparation of novel materials and precursors for catalysts, membranes, high-performance ceramics, hydride storage media, raw material for powder metallurgy, and nanoparticles. The emerging applications in organic synthesis reactions and environmental protection will undoubtedly also lead to broader applications. 

V.M. Gryaznov, Platinum Metals as Components of Catalyst-Membrane Systems , Platinum Metals Rev., 36 [2] 70-79 (1992). 

Catalyst-Membrane Combinations A Different Types of CMRs... 

The reliability/durability of these fuel cells is another major barrier hindering commercialization. Developing durable catalysts, membranes, gas diffusion layers, and bipolar plates are currently the major areas of concentration in the search for technical breakthroughs. 

An innovative way of immobilizing a catalyst solution for a homogeneous catalytic reaction while simultaneously separating the produces) and reactant(s) was demonstrated by Kim and Datta [1991] who called it supported liquid-phase catalytic membrane reactor-sqiarator. The basic concept involves a membrane-catalyst-membrane composite as depicted in Figure 8.1 for a simple reaction ... 

Gasoline and other higher hydrocarbons may be converted to hydrogen on board cars by the autothermal processes, using suitable catalysts (Ghen-ciu, 2002 Ayabe et ah, 2003 Semelsberger et ah, 2004). Partial oxidation may also be combined with the palladium-catalyst membrane reactors mentioned in section 2.1.1 (Basile et ah, 2001). 

Figure 3.33. Schematic picture of a proton exchange membrane fuel cell. Modelling of reactions at the gas diffusion layer/catalyst/membrane interfaces A and B is discussed in section 3.5.2. Details of design are discussed in the following subsections.

The gas diffusion layer (GDL) must be capable of transporting gases (hydrogen or oxygen) from the gas input channels to the active area at the catalyst-membrane interface. At the same time, it must be able to transport electrons to or from the active area and deliver them to or take them from the... 

Catalyst-membrane systems are promising structured catalysts. The perspectives for control of heterogeneous catalytic reactions by the combination of a catalyst and a membrane selectively permeable for one of the reactants have been discussed [1]. Catalyst-membrane systems enhance reaction rate and selectivity due to the directed transfer of reactants and energy. 

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