Industrial electrolysis

EEC Directive on mercury (chlor-alkali electrolysis industry)... 

EEC Directive on mercury from non-chlor-alkah electrolysis industry 84/491/EEC Directive on hexachlorocyclohexane discharges... 

Recently, rhodium and ruthenium-based carbon-supported sulfide electrocatalysts were synthesized by different established methods and evaluated as ODP cathodic catalysts in a chlorine-saturated hydrochloric acid environment with respect to both economic and industrial considerations [46]. In particular, patented E-TEK methods as well as a non-aqueous method were used to produce binary RhjcSy and Ru Sy in addition, some of the more popular Mo, Co, Rh, and Redoped RuxSy catalysts for acid electrolyte fuel cell ORR applications were also prepared. The roles of both crystallinity and morphology of the electrocatalysts were investigated. Their activity for ORR was compared to state-of-the-art Pt/C and Rh/C systems. The Rh Sy/C, CojcRuyS /C, and Ru Sy/C materials synthesized by the E-TEK methods exhibited appreciable stability and activity for ORR under these conditions. The Ru-based materials showed good depolarizing behavior. Considering that ruthenium is about seven times less expensive than rhodium, these Ru-based electrocatalysts may prove to be a viable low-cost alternative to Rh Sy systems for the ODC HCl electrolysis industry. 

Council Directive of 22 March 1982 on limit values and quality objectives for mercury discharges by the chlor-alkali electrolysis industry (OJ No L81, 27.3.82, p.29). 

Proposal for a Directive concerning the chloralkali electrolysis industry sent to the Council on 20 June 1979, adopted on 22 March 1982 (OJ No L81, 27.3.1982). Proposal for a Directive on other industries in preparation... 

Nickel, which is not as electrocatalytically active as iron toward the HER, exhibits excellent corrosion resistance in hot, concentrated, alkaline solutions. Motivated by the stability of Ni in caustic solutions (Fig. 4.6.3) and the extensive investigations by tire water electrolysis industry to develop Ni-based cathodes, significant efforts have been made to develop catalytic cathodes for application in chlor-alkali cells. 

The shape of the electrode is indicated by its function and the nature of the product. In aluminium electrowinning, the cell body serves as the cathode in the water electrolysis industry both of the electrodes are simple vertical... 

Fluorine cannot be prepared directly by chemical methods. It is prepared in the laboratory and on an industrial scale by electrolysis. Two methods are employed (a) using fused potassium hydrogen-fluoride, KHFj, ill a cell heated electrically to 520-570 K or (b) using fused electrolyte, of composition KF HF = 1 2, in a cell at 340-370 K which can be electrically or steam heated. Moissan, who first isolated fluorine in 1886, used a method very similar to (b) and it is this process which is commonly used in the laboratory and on an industrial scale today. There have been many cell designs but the cell is usually made from steel, or a copper-nickel alloy ( Monel metal). Steel or copper cathodes and specially made amorphous carbon anodes (to minimise attack by fluorine) are used. Hydrogen is formed at the cathode and fluorine at the anode, and the hydrogen fluoride content of the fused electrolyte is maintained by passing in... 

The reduction of acrylonitrile, CH2=CHCN, to adiponitrile, NC(CH2)4CN, is an important industrial process. A 0.594-g sample of acrylonitrile is placed in a 1 -L volumetric flask and diluted to volume. An exhaustive controlled-potential electrolysis of a 1.00-mL portion of the diluted acrylonitrile requires 1.080 C of charge. What is the value of n for this reduction ... 

Zirconium trifluoride [13814-22-7], ZrP, was first prepared by the fluorination of ZrH2 using a mixture of H2 and anhydrous HP at 750°C (2). It can also be prepared by the electrolysis of Zr metal in KF—NaF melts (3). Zirconium trifluoride is stable at ambient temperatures but decomposes at 300°C. It is slightly soluble in hot water and readily soluble in inorganic acids. This compound is of academic interest rather than of any industrial importance. 

The electrochemical route to duoroaromatics (90) based on controlled potential electrolysis in the absence of hydrogen duoride (platinum anode, +2.4 V acetonitrile solvent tetraalkylammonium duoride electrolyte) has not been commercialized. However, considerable industrial interest in the electrochemical approach stiU exists (91—93). 

Potential fusion appHcations other than electricity production have received some study. For example, radiation and high temperature heat from a fusion reactor could be used to produce hydrogen by the electrolysis or radiolysis of water, which could be employed in the synthesis of portable chemical fuels for transportation or industrial use. The transmutation of radioactive actinide wastes from fission reactors may also be feasible. This idea would utilize the neutrons from a fusion reactor to convert hazardous isotopes into more benign and easier-to-handle species. The practicaUty of these concepts requires further analysis. 

These reactions can be carried out at room temperature. Hydrogen gas can also be produced on a laboratory scale by the electrolysis of an aqueous solution. Production of hydrogen through electrolysis is also used industrially. This involves the following reaction at the cathode of the electrochemical cell ... 

Water-Splitting Techniques. Only one water-sphtting method, electrolysis, is practiced industrially for the production of hydrogen, and that only to a limited extent. 

The deposition of RE metals from aqueous solutions does not work because of the highly electropositive nature of the REE. Therefore, industrial production of RE metals is carried out by fused salt electrolysis or metaHothermic reduction. 

The matte can be treated in different ways, depending on the copper content and on the desired product. In some cases, the copper content of the Bessemer matte is low enough to allow the material to be cast directly into sulfide anodes for electrolytic refining. Usually it is necessary first to separate the nickel and copper sulfides. The copper—nickel matte is cooled slowly for ca 4 d to faciUtate grain growth of mineral crystals of copper sulfide, nickel—sulfide, and a nickel—copper alloy. This matte is pulverized, the nickel and copper sulfides isolated by flotation, and the alloy extracted magnetically and refined electrolyticaHy. The nickel sulfide is cast into anodes for electrolysis or, more commonly, is roasted to nickel oxide and further reduced to metal for refining by electrolysis or by the carbonyl method. Alternatively, the nickel sulfide may be roasted to provide a nickel oxide sinter that is suitable for direct use by the steel industry. 

For well over 100 years after its discovery and initial preparation, oxygen was made either chemically or by the electrolysis of water. Early in the twentieth century, Linde and Claude introduced processes for the Hquefaction and distillation of air that have since grown into a mature and highly competitive industry. In 1991, over 13.4 X 10 (4.7 x 10 ft ) of oxygen was produced in the United States. About 70 X 10 (24.7 x 10 ft ) was... 

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