Hydrogen Transport Membranes in the Chemical Industry

If the catalytic conditions at the membrane permeate surface are not optimum for the desired chemical reaction, for example, due to constraints of membrane operating temperature dictated by the temperature of the retentate, desorbed molecular hydrogen may be consumed immediately downstream in catalytic reactors 

Molecular hydrogen may be oxidized in fuel cells placed downstream from the membrane permeate surface, leading to hydrogen concentration gradients from the membrane permeate surface to the point of consumption. Steam, if available at low cost, or if desired downstream, may be used as a sweep gas. Pumps or compressors, designed especially for use with hydrogen, can also be used to create pressure gradients downstream from the membrane permeate surface. 

Other patented (nonporous) methods to provide support for thin membranes include the cylindrical screens for supporting thin membrane tubes of Bonnet [22], the metal gauze of Juda and Novack [23], the Dutch weave wire netting of Yamauchi, et al. [24], the circular screens of Bonnet [25], the perforated conduits of Eguchi et al. [26], the helical wires of Hollister and Stiles [27], the square perforations of Prolss [28], the corrugated screens of Iniotakis et al. [29], and the var- 

Membrane Hydrogen Dissociation Catalysts and Protective Layers 

In principle, all atomically clean transition metals will adsorb and dissociate molecular hydrogen. For noble metals such as palladium, which do not readily form stable oxides, carbides and nitrides under membrane operating conditions, no additional catalyst or protective layer is normally required. However, for the less noble metals, and especially for highly reactive metals including Nb, Ta, H, V and Zr, surface layers of oxides, carbides and nitrides will rapidly form and poison 

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