Liquid hydrogen production process

Sakurai, M., Nakajima, H., Onuki, K., and Shimizu, S., Investigation of two liquid phase separation characteristics on the iodine-sulfur thermochemical hydrogen production process. International Journal of Hydrogen Energy, 25, 605-611, 2000. 

By-product processing Hydrogen sulfide Conversion to elemental sulfur or sulfuric acid by liquid absorption, wet oxidation to elemental sulfur, combustion to SO2... 

In the industrial process, the chlorocarbon and liquid hydrogen fluoride feeds are pumped simultaneously into a complex liquid mixture of Sb(lII) and Sb(V) chlorofluondcs at temperatures in the 60-150 °C range The products are generally more volatile than the reactants and therefore distill preferentially from the reactor vessel, thus the reactor can be operated continuously. 

A schematic diagram of the liquid solvent extraction process is illustrated in Figure 1. Where the production of liquid hydrocarbons is the main objective an hydrogenated donor process solvent is used, whereas in the production of needle coke this is not necessary and a coal derived high boiling aromatic solvent may be used (e.g. anthracene oil). An essential economic requirement of the process is that a high extraction yield of the coal is obtained and this will depend upon the coal used and the digestion conditions. 

Schematic diagram of hydrogen production by SMR process coupled with ocean C02 sequestration. C02 sequestration techniques (a) = L-C02 droplet plume option and (b) = liquid C02 lake option.

Some metals such as Pd and Nb can dissolve hydrogen in atomic form in their lattice. For other metals as Cu, Ag, Au, Pt, Rh, this phenomenon is usually absent. If these latter metals contain traces of hydrogen (10-100 ppm, due to the production process), there is the formation of small gas bubbles with a typical diameter around 10 4mm [21]. The pressure of hydrogen, which is in the molecular form, inside the bubbles, is very high, and hydrogen becomes liquid or solid when the metal is cooled. Hence also in this case, a heat release due to the ortho to para conversion takes place [22,23]. The thermal release is of the order of 1 nW/g nevertheless it may be important in experiments at extremely low temperatures. 

Syngas cleanup system - low or high temperature and processes used to remove sulfur, nitrogen, particulates, and other compounds that may impact the suitability of the syngas for specific applications (i.e., turbine and fuel cell for electric power generation, hydrogen production, liquid fuel production, or chemical production). 

In the ideal biphasic hydrogenation process, the substrate will be more soluble or partially soluble in the immobilization solvent and the hydrogenation product will be insoluble as this facilitates both reaction and product separation. Mixing problems are sometimes encountered with biphasic processes and much work has been conducted to elucidate exactly where catalysis takes place (see Chapter 2). Clearly, if the substrates are soluble in the catalyst support phase, then mixing is not an issue. The hydrogenation of benzene to cyclohexane in tetrafluoroborate ionic liquids exploits the differing solubilities of the substrate and product. The solubility of benzene and cyclohexane has been measured in... 

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