Hydrogen by electrolysis of water

The simplest kind of cell construction, shown in Figure 19.19(d), suffices for the production of hydrogen by electrolysis of water and for the recovery of chlorine from waste HC1. The term filter-press cell is applied to this kind of equipment because of the layered construction. These two electrolyses are economically feasible under some conditions. Some details are given by Hine (1985). 

For small hydrogen requirements it is possible to economically reform methanol especially if there is a low cost supply of methanol by-product available. This is an economical alternative to liquid hydrogen purchase or generation of gaseous hydrogen by electrolysis of water for quantities in the range of 100-2000 N mVh (3500-7000 SCF/h). The process developed by... 

Volume production of hydrogen by electrolysis of water is achieved using one of the following process variants ... 

Since 1960, about 95% of the synthetic ammonia made in the United States has been made from natural gas worldwide the proportion is about 85%. Most of the balance is made from naphtha and other petroleum Hquids. Relatively small amounts of ammonia are made from hydrogen recovered from coke oven and refinery gases, from electrolysis of salt solutions, eg, caustic chlorine production, and by electrolysis of water. In addition there are about 20 ammonia plants worldwide that use coal as a hydrogen source. 

Total production of hydrogen in the United States in 1988 was 61.5 x 10 (49). Total hydrogen production by electrolysis of water in 1988 was... 

Deuterium discovered specU oscopically and enriched by gaseous diffusion of hydrogen and by electrolysis of water (H. C. Urey, F. G. Brickwedde and G. M. Murphy). 

Self-Test 4.13B Students collecting hydrogen and oxygen gases by electrolysis of water failed to separate the two gases. If the total pressure of the dry mixture is i 720. Torr, what is the partial pressure of each gas ... 

Another problem encountered by manufacturers and users of NiCads batteries is the breakdown, by electrolysis, of water. This ought to be prevented otherwise the cells may explode. As with lead-acid batteries, NiCads are also prone to electrolysis-mediated breaking down of water in the electrolyte into potentially explosive hydrogen and oxygen. Battery manufacturers take great steps... 

Analogous to the formation of metal hydrides, a technique has been proposed in which carbons are used to sorb hydrogen produced in situ by electrolysis of water. Here, the carbon is used as a negatively polarized electrode. The process itself is attractive considering... 

Oxygen can be produced by electrolysis of water using a salt as an electrolyte that produces hydrogen at the opposite electrode. When potassium chlorate (KClOj) is heated in a test tube with a small amount of manganese dioxide (MnO ) as a catalyst, the chemical reaction that releases the oxygen from potassium chlorate will be accelerated. Use of potassium nitrate (KNOj) will also produce small amounts of oxygen. 

Hydrogen gas may be produced by several methods. It is commercially obtained by electrolysis of water. It also is made industrially by the reaction of steam with methane or coke ... 

Oxygen may be produced by electrolysis of water. In such electrolytic procedure, small amounts of H2SO4 or NaOH may be added to water. Electrolysis methods, however, are not used as much commercially as are air bquefaction processes which cost less. However, in making hydrogen from water by electrolysis, oxygen is obtained as a by-product. 

Hydrogen is produced as a by-product of the refining of fossil fuels and by electrolysis of water. It has a low density and weak intermodular forces. Hydrogen is a good reducing agent for species with positive standard potentials. 

The purest hydrogen (>99.95% pure) is made by electrolysis of water. However, this process requires a large amount of energy—286 kj per mole of H2 produced— and thus is not economical for large-scale production. 

Small amounts of 02 can be prepared in the laboratory by electrolysis of water, by decomposition of aqueous hydrogen peroxide in the presence of a catalyst such as Fe3+, or by thermal decomposition of an oxoacid salt, such as potassium chlorate, KC103 ... 

Where inexpensive electric power is available, for example off-peak hydro-power or nuclear power, hydrogen can be produced by electrolysis of water. Another approach is to use solar energy to "split" water into H2 and 02. The feasibility of this scheme depends on the development of catalysts that absorb sunlight and then use the energy to reduce water to hydrogen. 

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