Palladium Membrane Micro Reactor

Franz et al. [93] developed a palladium membrane micro reactor for hydrogen separation based on MEMS technology, which incorporated integrated devices for heating and temperature measurement. The reactor consisted of two channels separated by the membrane, which was composed of three layers. Two of them, which were made of silicon nitride introduced by low-pressure chemical vapor deposition (0.3 pm thick) and silicon oxide by temperature treatment (0.2 pm thick), served as perforated supports for the palladium membrane. Both layers were deposited on a silicon wafer and subsequently removed from one side completely 

Starting Material Si wafer covered with a layer of oxide and nitride 

Backside KOH etch, to form channel/membrane structure 

The performance of the membrane was tested with a mixture of 90% nitrogen and 10% hydrogen at atmospheric pressure and 500 °C. The permeate side of the membrane was set under vacuum. A hydrogen flux of 100 Ndm3 m-2 s-1 was determined at the pressure drop of 1 bar. 

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Figure 2.63 Micro fabrication sequence for the silicon component of the palladium membrane reactor [93] (by courtesy of Springer-Verlag).

For membranes implemented in the second reactor only the results of micro-porous membranes will be discussed in detail, because palladium membranes gave almost the same results and the performance is better than that of Knudsen diffusion membranes. The yield and selectivities have been calculated at different permeate pressures and are plotted in Fig. 14.11. The results for the conventional reactor are obtained without a membrane implemented in the process. 

Figure 8.16 shows a methanol/water vaporiser, followed by a catalytic steam reformer operating at about 250°C, in which the catalyst is a thin film of Cu/ZnO coated onto the silica reactor, and finally a membrane shift reactor consisting of a palladium diffusion layer mounted on top of a perforated copper-based shift catalyst. Built onto the chip are integrated resistive heaters for getting the reformer and vaporiser up to temperature, together with micro-scale sensors and control electronics. Whilst such systems are a long... 

Computational fluid dynamics (CFD) analysis of membrane reactors simulation of a palladium-based membrane reactor in fuel cell micro-cogenerator system... 

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