Pressurized hydrogen

The volumetric hydrogen density describes the mass of hydrogen in a material or a system divided by the volume of the material or storage system  

The most established storage systems are high-pressure gas cylinders with a maximum pressure of 20 MPa. New lightweight composite cylinders have been developed that are able to withstand pressures up to 80 MPa and so the hydrogen can reach a volumetric density of 36 kg m, approximately half that in its liquid form at the normal boiling point. 

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Lorenzana FI E, Silvera I F and Goettel K A 1990 Order parameter and a critical point on the megabar-pressure hydrogen-A phase line Phys. Rev. Lett. 65 1901... 

It has been stated that the activity of the catalyst in low pressure hydrogenations is enhanced by the addition of small quantities of platinic chloride. 

Sorbitol is a sweetener often substituted for cane sugar because it is better tolerated by dia betics It IS also an intermediate in the commercial synthesis of vitamin C Sorbitol is prepared by high pressure hydrogenation of glucose over a nickel catalyst What is the structure (including stereochemistry) of sorbitoP... 

High Pressure Hydrogenation at Ludwigshafen-Heidelberg," Vol. IA, FIAT Final Repod No. 1317, ATI No. 92,762, Central Air Documents Office, Dayton, Ohio, 1951. 

Temperatures higher than about 300" and pressures higher than 6000 lb. per sq. in. should not be used in the vessels and with the gauges ordinarily supplied for high-pressure hydrogenations. Only clean equipment, in first-class condition, and under careful control, can be used safely and successfully in carrying out reactions under the conditions described. 

Walter, R. J., and Chandler, W. T Effects of High Pressure Hydrogen on Storage Vessel Materials, paper presented at meeting of American Society for Metals, Los Angeles, March 1968. 

A suitable apparatus is the Aminco high-pressure hydrogenation apparatus, manufactured by the American Instrument Company, Silver Springs, Maryland. 

At elevated temperature and pressure hydrogen embrittlement can result Most metals when gas is moist. Galvanized pipe or brass or bronze fittings... 

Hydrazoic acid Hydrides, volatile Hydrogen cyanide (unstabilized) Hydrogen (low pressure) Hydrogen peroxide (> 35% water) Magnesium peroxide Mercurous azide Methyl acetylene Methyl lactate Nickel hypophosphite Nitriles > ethyl Nitrogen bromide... 

The perhydroisoindole system can be prepared by high-pressure hydrogenation of the isoindole over nickel on alumina at elevated temperatures. The use of Raney nickel with dioxane in the reduction of l,3-diphenyl-2-methylisoindole (47) gives the perhydro product (96), accompanied by the isoindoline (97). An alternative route to partially hydrogenated isoindoles has been described in Section III, D. 

Catalytic hydrogenation of 2-cyano-l-(2-nitrophenyl)piperidines over Pearlman s catalyst in a low-pressure hydrogenator under 1 atm of hydrogen in dioxane gave cyclic amidine A -oxides 352 (01EJOC987). 

The technique of catalytic hydrogenation can be applied almost universally to unsaturated systems, and therein lies its chief advantage (7). By appropriate selection of catalyst, pressure, and temperature, a remarkable variety of substrates can be made to undergo hydrogenation, many of them under hydrogen pressure not exceeding 50 psi (see Appendix 3 for description and use of low-pressure hydrogenation apparatus). 

II. Low-Pressure Hydrogenation of Phenols over Rhodium Catalysts... 

Fig. A3.9. Low-pressure hydrogenation apparatus (Parr Instrument Company).

In a stainless steel hydrogenation bottle were placed 17.6 g (0.1 mol) of 4-(p-methoxyphenyl)-3-buten-2-one, 80 ml of ethyl acetate, and 1 g of Raney nickel catalyst. The hydrogenation bottle was attached to a Paar low-pressure hydrogenation apparatus and the solution was hydrogenated under an initial hydrogen pressure of 50 psi. The hydrogenation was carried out at room temperature and after about 12 hours one equivalent of hydrogen had been absorbed. The catalyst was filtered from the reduction mixture and 18.1 g (0.1 mol) of homoveratrylamine were added to the reduction mixture. 

A corresponding pressure effect on the flow stress was observed on hydrostatic extrusion of conical specimens of the same alloy through a die of 5 mm dia at 220°C. The basic alloy was extruded at P = 12 kbar up to the area ratio equal to 4.1 while the alloy hydrogenated to a = 0.20 extruded to the area ratio of 7.6 even at a lower pressure, P = 11 kbax . Similar pressure/hydrogen effects on the flow stress were also observed on hydrostatic extrusion of ZrH,c, VH,c and Nb,c alloys with x = 0 and 0.1-0.2 wt.%. 

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