Chlorine from electrolysis

Explosion Hazards. The electrolysis of aqueous solutions often lead to the formation of gaseous products at both the anode and cathode. Examples are hydrogen and chlorine from electrolysis of NaCl solutions and hydrogen and oxygen from electrolysis of water. The electrode reactions. 

The only reasonably successful advance in this sense is the Alcoa process, based on the electrolysis of aluminium trichloride in a 2-15 per cent concentration at 700°C in a 3 2 mixture of molten sodium chloride and potassium chloride using carbon electrodes. Aluminium oxide is previously converted into aluminium chloride using chlorine from electrolysis. The reactions are thus... 

The main raw material for the primary chlorine production is sodium chloride. The chlorine from electrolysis plants supplies about two third of the chlorine demand. 

Chlorine from HCl. Most organic chlorination reactions consume only half the CI2 to produce the desired product the other half is converted to HCl. Depending on demand and supply of CI2 vs HCl, chlorine recovery from hydrochloric acid is sometimes attractive. Two commercial routes are available electrolysis and oxidation (69). 

Chlorine from the Magnesium Process. Magnesium is produced by the fused salt electrolysis of MgCl2 (see Magnesium and magnesium... 

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. 

In general, the electrolysis of a molten salt at inert electrodes produces the metal at the cathode, e.g., calcium from calcium chloride (melting point 774 °C). The anion is often a halide ion which, on discharge, yields the halogen, e.g., chlorine from calcium chloride. 

As was noted above, functional fluoropolymers produced by copolymerization of fluoroolefins with functional PFAVE have several unique properties, with the main disadvantage of these materials being the extremely high cost of functional monomers and the resulting high cost of the functional polymers produced from them. The fact that they are so expensive limits their wider industrial application in other fields such as catalysis and membrane separation, except for chlorine-alkali electrolysis and fuel cells, where the only suitable materials are fully fluorinated polymers because of the extreme conditions associated with those processes. 

With respect to the German case study used in Chapter 14 to discuss the build-up of a hydrogen infrastructure, Fig. 10.9 shows where surplus hydrogen capacities (from chlorine-alkali electrolysis) exist in Germany. If these capacities are added up, the resulting total amount is about 1 billion Nm3 per year (around 4% of total German hydrogen production). 

Dormagen and from chlorine-alkali electrolysis in Leverkusen, to feed this into the hydrogen pipeline network of the... 

Since the products of the electrolysis of aqueous NaCl will react if they come in contact with each other, an essential feature of any chloralkali cell is separation of the anode reaction (where chloride ion is oxidized to chlorine) from the cathode reaction (in which OH- and H2 are the end products). The principal types of chloralkali cells currently in use are the diaphragm (or membrane) cell and the mercury cell. 

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). 

All the free halogens are produced commercially by oxidation of their anions. Fluorine and chlorine are both produced by electrolysis fluorine from a molten 1 2 mixture of KF and HF, and chlorine from molten NaCl. 

Since chloramine itself is prepared by chlorination of ammonia, hydrazine is generally prepared by treatment of excess ammonia with chlorine. The similarity to H2O2 is exemplified by the detection of hydrazine at the anode in electrolysis of ammonium salts, just as H2Q2 or its derivatives can result from electrolysis of aqueous acid solutions. 

Chlorine and sodium hydroxide are made by the electrolysis of brine using membrane cells. Conventional and improved membrane cell arrangements are described in U.S. 4,391,693, assigned to Dow Chemical. U.S. 4,470,889 (also to Dow) gives data on membrane materials and performance. What price of electricity is needed for it to be economical to produce chlorine from sea water (3.5 wt% NaCl) ... 

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