Efficiency hydrogen separation

Carbon Dioxide Separation for Fuel Reforming Carbon dioxide separation reforming in the above mentioned is one of useful methodologies for efficient hydrogen production [29]. Calcium oxide (CaO) carbonation can absorb CO2 from the reformed gas and fix it. 

Fig. 3. Current efficiency for hydrogen separation. Calculated overall energy efficiency vs. current density of hydrogen purification for conditions of Table 1 including reversible work O excluding reversible work.

The maximum difference in phase separation temperature was observed at a very small azobenzene content of 2.7 mol%. Below and above this content, the phase separation was not affected by photoirradiation. This fact indicates that the phase transition temperature depends on a subtle balance between the polymer s ability of hydrogen bond formation with water and the intermolecular hydropholic force. The isomerization of a small number of azobenzene chromophores (2-3 mol %) effects the balance, resulting in an efficient phase separation. 

The exhaust gases contain CH4, N2, H2O, tar, acidic and basic compounds (NH3, HCN, H2S) considered as impurities. Tar conversion has to be controlled to maximize the reliability of mechanical equipments and to assure the operation of the successive clean-up catalytic steps for final hydrogen separation and purification [64]. This step involves the utilization of additional steam and selective catalysts, affecting the overall efficiency of the process [65]. The operation with oxygen instead of air may improve the efficiency of the process but it suffers the costs associated with air liquefaction process, necessary for O2/N2 separation. 

The increase in the solubility of HgSe(s) with increasing hydrogen selenide and selenide activities is well documented at high pH and the third equilibrium constant is accepted by the review. The first constant, which equals an intrinsic solubility of HgSe(s) is most likely too large due to the rather simple method used for the separation of solid material from the aqueous phase. It is tentatively included due to its potential importance in connection with the mobility of mercury from repositories. Further investigations with a more efficient phase separation technique would be welcome here. 

---