Hydrogen continued liquefaction

The reactive role of liptinite macerals in liquefaction has been partially documented (50,68). However, recent work has shown that unaltered sporinite often is encountered in the residues from both batch and continuous liquefaction runs. For example, sporinite was a common component in the residues of a high volatile A bituminous coal after hydrogen-transfer runs at 400° for 30 minutes (70). In spite of the relative unreactivity of the sporinite in this instance, the vitrinite clearly had reacted extensively because vitroplast was the predominant residue component. The dissolution rate of sporinite from some coals, even at 400°C, may be somewhat less than that of vitrinite. 

The large amount of energy necessary for liquefaction, that is, 40% of the upper heating value, makes liquid hydrogen not an energy-efficient storage medium. Furthermore, the continuous boil-off of hydrogen limits the possible applications... 

After World War II, direct liquefaction of coal became uneconomical as the use of lower-cost petroleum products became more widespread. However, the German process of indirect coal liquefaction, the Fischer-Tropsch process, continued to hold some interest. The Fischer-Tropsch process first involved production of a carbon monoxide and hydrogen-rich synthesis gas by the controlled gasification of coal followed by a catalytic reaction process to yield a valuable mixture of hydrocarbon products. Simplified Fischer-Tropsch reactions are shown by the following equations ... 

Low-temperature adsorption systems continue to find an increasing number of applications. For example, systems are used to remove the last traces of carbon dioxide and hydrocarbons in many air-separation plants. Adsorbents are also used in hydrogen liquefaction to remove oxygen, nitrogen, methane, and other trace impurities. They are also used in the purification of helium suitable for liquefaction (grade A) and for ultrapure helium (grade AAA, 99.999% purity). Adsorption at 35 K will, in fact, yield a helium with less than 2 ppb of neon, which is the only detectible impurity in helium after this treatment. 

Liquefaction units (not to be confused with the hydrogenation processes) using continuous stirred tank reactors, at Niigata and Sapporo. 

The gas displaced from the tank will flow up the outer coaxial line to the dispenser for liquefaction or disposal. Flow of liquid hydrogen will continue until the automobile tank is full. 

The logistics of transportation of by-product hydrogen sulfide will play an important part in the ultimate use of this material. Intra-plant transfers will continue to be by pipeline as currently practiced in petroleum refineries and gas plants. Inter-plant transfers for more than very short distances will likely involve liquefaction of the hydrogen sulfide and movement by tank trucks or tank cars. 

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