Ultra-high purity hydrogen production

Ceramic Membrane Devices for Ultra-High Purity Hydrogen Production Mixed Conducting Membrane Development... 

The constricted part of the tube (Fig. la) was then sealed off, sample transferred in vacua into the Infrasil cell and reduced by hydrogen (Ultra-high purity, Air Products) at 1 atm and 200°C for 14 h in an apparatus (Fig. lb). The temperature of 200°C gives rise to almost complete reduction of the Cu Y to Cu Y without reducing further to Cu° (4). ... 

Traditionally PSA processes have found particularly widespread application in hydrogen production systems wherein the PSA unit is used to produce ultra-high purity hydrogen (99.999%+) from steam-reformed hydrocarbons and other hydrogen sources. However, several limitations have existed with these processes. 

Purification methods have been developed which usually involve conversion of silicon into volatile silanes which are then subjected to fractional distillation, and converted back to silicon. The Siemens process, Equations 3.2 and 3.3, involves the production of SiHCl3 by reacting silicon with HCl. Following fractional distillation, the halide is reduced with hydrogen at about 1 000 °C to produce rods of ultra-high purity silicon (Figure 3.2). 

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