Reduction natural processes

The intermediary is often forced to present complex material in a simple manner, i.e., to carry out a didactic reduction . Such processes naturally cause problems, resembling a walk on a jagged mountain ridge. On the one side is the abyss of an inordinate simplification of the scientific conclusions (and the resulting condemnation by the experts), on the other that of the complexity of scientific thought, which is only really understood by the specialist. 

Armco A direct reduction ironmaking process which used natural gas as the reductant. Operated in Houston, TX, from 1972, dismantled in 1982. See DR. 

HyL [Hojalata y Lamina] A direct reduction ironmaking process in which pellets or lumps of ore are reduced in a batch reactor using a mixture of hydrogen and carbon monoxide. Used in countries which have natural gas and cannot afford to invest in blast furnaces. Developed in the 1950s in Mexico by the Hojalata y Lamina Steel Company (now Hylsa) and the MW Kellogg Company, and now operated in nine other countries too. See DR. 

Plasmared [Plasma reduction] A direct reduction ironmaking process, using natural gas as the reductant and heated by an electric plasma. Operated in Sweden by SKF from 1981 to 1984. See DR. 

When CFCs slowly rise in the atmosphere and reach the ozone layer, they are broken down into component molecular compounds and atoms by the UV rays of the sun. Some of these chemicals then react with ozone to break it down, thus reducing the amount of O3. Further, some chlorine (also from the oceans) and some other elements combine with the O and to form other chemicals. This also contributes to the reduction of ozone faster than natural processes can reform it. Ozone is a renewable resource. The issue is this can a balance be obtained between the destruction of ozone in the atmosphere, by both natural and man-made causes, and its natural regeneration ... 

From the lithium chemistry point of view, the carbon-fluorine bond cannot be considered as a carbon-halogen bond because alkyl or aryl fluorides are not adequate starting materials in lithiation processes, due to the fact that this bond is the strongest that carbon can form . On the other hand, a possible reductive defluorination process could be important from an environmental point of view due to the difficult degradation of fluoro derivatives in nature . 

The reduction of C02 to cellulose occurs in the natural process of photosynthesis. It involves the photoelectrochemical reduction of water to hydrogen and oxygen (Bockris and Tunulli, 1980) and the subsequent formation of CH20 by chemical steps from the released H2 and C02. This natural process gives rise to expectations of the possibilities of fixing atmospheric C02 by artificial photoelectrochemical means. The best would be if one could form methanol photoelectrochemically from the inexhaustible supply of C02 in the air. 

The SCR technology can be used in any nitric acid plant. The costs per tonne of CO2 equivalents removed range from 1.3 to 3.0 EUR. The reductant (natural gas or LPG) is the largest cost item in these processes and makes up 20% to 60% of the total costs221. 

Photocatalytic C02 reduction over simple oxide semiconductors, although characterized by low efficiencies, might contribute to natural processes occurring in atmosphere of young Earth (see section 10.3, Chapter 10). More sophisticated systems developedi in future may be useful for C02 utilization as a substrate for production of chemicals. Until now yields of these processes, usually allowing formation of micromoles of products, are still not sufficient. Selected examples of C02 reduction in heterogeneous photocatalytic systems are described below. 

When anything burns in air or oxygen, it is by a process of oxidation/reduction. Natural gas CH4 burns in air ... 

Reduction of nitroaromatics is a well-studied reductive transformation process. Major steps in the reduction are important naturally occurring organic reductants ... 

In this paper aspects of the carbon dioxide chemistry we have developed will be reviewed and discussed with reference to relevant natural processes. A few examples of utilisation of either enzymes or biomimetic systems will be presented, covering both the fixation and reduction reactions. 

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