Hydrogen overpressure

In the near future, the possible synthesis of nanotubes with solid-gas potential will be more favorable to adsorption. The effect of hydrogen overpressure on the stability of adsorbed Ha needs to be verified in the near future. The high-purity nanotube produced by laser vaporization, catalytic decomposition, or other techniques should be investigated. It is noteworthy that the synthesis of the SWNT with defined diameters and distances between the walls is difficult to perform at present, but future synthesis routes will allow more... 

Added Tetralin, hydrogen overpressure and increased solvent-to-coal ratios resulted in no measurable increase in gas yield. 

SI. The effects of coal characteristics on conversions are generally much less pronounced under high-severity conditions en a combination of vehicle solvent, hydrogen overpressure and catalyst is employed. 

In this paper, a number of low-severity liquefaction regimes are considered. The influence of different H-donor and non-donor solvents on primary conversions without a hydrogen overpressure is discussed in the light of other recent work (10-131. Also, it is demonstrated that oil yields broadly increase with decreasing coal rank in both H-donor extraction and dry catalytic hydrogenation provided that retrogressive reactions are avoided in the initial stages of coal dissolution. 

Typical transfer times between autoclaves were 5 to 10 seconds. The reactants were stirred rapidly and the hydrogen overpressure, typically 1500 psig added hydrogen, was added quickly to AC2. 

For an ideal gas, the hydrogen overpressure, P, in equilibrium with the hydride at temperature T, can then be expressed in the form ... 

Mechanism and reaction intermediates of the hydrogen oxidation reaction on platinum have been studied with SEIRAS [324]. A band observed around 2090 cm was assigned to adsorbed hydrogen species and the band height dependency on electrode potential and hydrogen overpressure was found to match values predicted on the basis of the Volmer-Tafel mechanism. 

Tayout also has a significant role in minimizing the probability of ignition of a flammable release. Area electrical classification provides the basis for the control of electrical ignition sources. This classification is also used to determine the areas that require protection from vehicular access, etc. Frequently, highly hazardous processes that can result in overpressure (e.g., hydrogenation) are placed behind blast resistant structures/walls. 

Overpressure, overtemperature, hydrogen explosion, steam explosion, and core melt through are mechanisms that may fail the containment of nuclear and chemical reactors,... 

Similarly, if the vent is designed to pass liquid, it should be fitted near the edge of the roof, and its top should not be more than 8 in. above the tops of the walls. Vessels have been overpressured because their vent pipes were too long (see Figure 5-2b). Tanks in which hydrogen may be evolved should be fitted with a vent at the highest point as well as an overflow (see Section 16.2). 

The results in Tables 4. la and 4. lb demonstrate that in the absence of obstacles, the highest flame speed observed was 84 m/s, and it was accompanied by an overpressure of 60 mbar for hydrogen-air in a 10-m radius balloon (Schneider and Pfortner 1981). For all other fuels, flame speeds were below 40 m/s and corresponding overpressures were below 35 mbar. Hence, weak ignition of an unconfined... 

In the methane and hydrogen jet experiments, blast static overpressure was measured at various distances from the cloud (Figure 4.6). The propane jet experi-... 

Figure 4.6. Decay of peak overpressure with distance for ignited subcritical 10-mm diameter hydrogen gas jets at various velocities, Uq. A = mean value.

Hot spot formation witliin tlie reactor can result in catalyst breakdown or physical deterioration of tlie reactor vessel." If tlie endothermic cyanide reaction has ceased (e.g., because of poor catalyst performance), the reactor is likely to overheat. Iron is a decomposition catalyst for hydrogen cyanide and ammonia under the conditions present in the cyanide reactor, and e. posed iron surfaces in the reactor or reactor feed system can result in uncontrolled decomposition, which could in turn lead to an accidaital release by overheating and overpressure. 

Aluminium powder can (depending on the surface texture of the metal) react with water, forming hydrogen, which can provoke explosions due to the overpressures created if the interaction occurs in a closed container. The same thing happens, whatever the surface texture, if the reaction occurs with an aqueous sodium hydroxide solution. 

Anaqueous aluminium chloride is dangerous. In contact with water, it hydrolyses, forming hydrogen chloride. If it is kept in a closed bottle in which there are water traces, the overpressure that is created can cause the bottle to detonate. There have been numerous accidents illustrating this. 

There was an explosion in a closed steel container in which phosphoric acid was present with chloride ions. In these conditions, the hydrogen that is produced created an overpressure. 

Concentrated sulphuric acid is used to obtain anaqueous hydrogen chloride. There was an accident due to the overpressure created by the gas in a confined apparatus. This drying operation was also tried with silica. The exo-... 

Zinc gives an explosive reaction with manganese dichloride, whereas with calcium chloride, which was in a galvanised iron container, the detonation is blamed on the overpressure created by the release of hydrogen, which is formed in these conditions. 

There have been several accidents with metalloids detonation with fluorine very violent reaction with boron at 700°C, and ignition with white phosphorus. In the last case, the dangerous character of the reaction of the preparation of hydrogen iodide by distillation of the phosphorus/moist iodide mixture was also mentioned. The formation of phosphonium iodide often causes the conduits of the apparatus to block, which causes the apparatus to detonate due to overpressure. Several accidents involve this factor, which is not due to a reaction that is intrinsically dangerous. 

When it was submitted to a pressure of 955 bar and a temperature of 327°C and then violently compressed to 4860 bar, propylene detonated, creating an overpressure, which reached 10000 bar. It was thought that such a pressure rise would lead to the formation of methane and hydrogen. 

Butanol gave rise to aluminium tributanoate when it came into contact with equipment containing aluminium. The equipment detonated because of the overpressure created by the hydrogen formed. The exothermicity of this reaction is also a risk factor. 

---