Carbon dioxide reduction chemical reactions

The iron ores commercially used come from mostly BIF, i.e., iron oxides, Fe Oj or FOjO. How would you produce the iron metal from these ores The iron in these ores is in oxidized states, either Fe(II) or Fe(III). Fe(II) is two electrons short of the iron metal Fe (Fe(0)), and Fe(III) is three electrons short. Therefore, in order to produce the iron metal from the ores, you have to add electrons to the iron oxides. Such a chemical reaction is called reduction. In the modem industrial process, the reducing agent is coke, made from coal. It is essentially carbon, C. A carbon atom can gives four electrons to others when it turns to carbon dioxide. The chemical reactions involved are as follows ... 

As already mentioned, supercritical solvents have been used as chemical reaction solvents for a long time. However, their study in the context of clean processes or Green Chemistry is relatively recent It was during the 1990s that research on carbon dioxide as a reaction medium developed. The main goal was the reduction or complete ehmination of volatile organic solvents used in laboratory and industrial processes. 

Electron-transfer reactions occur all around us. Objects made of iron become coated with mst when they are exposed to moist air. Animals obtain energy from the reaction of carbohydrates with oxygen to form carbon dioxide and water. Turning on a flashlight generates a current of electricity from a chemical reaction in the batteries. In an aluminum refinery, huge quantities of electricity drive the conversion of aluminum oxide into aluminum metal. These different chemical processes share one common feature Each is an oxidation-reduction reaction, commonly called a redox reaction, in which electrons are transferred from one chemical species to another. 

Great promise exists in the use of graphitic carbons in the electrochemical synthesis of hydrogen peroxide [reaction (15.21)] and in the electrochemical reduction of carbon dioxide to various organic products. Considering the diversity in structures and surface forms of carbonaceous materials, it is difficult to formulate generalizations as to the influence of their chemical and electron structure on the kinetics and mechanism of electrochemical reactions occurring at carbon electrodes. 

The chemical processes occurring inside the blast furnace can be stated to start basically from the hot air coming into contact with the white-hot coke. The coke burns to form carbon dioxide. This reaction generates a very large quantity of heat, and it is this heat which maintains the high temperature necessary for the reduction process. As the gas is... 

A fundamental question for all reactions which could have been involved in the early phase of chemical evolution is that of the origin of the reduction equivalents necessary for the autotrophic synthesis. For example, the synthesis of one molecule of glucose from carbon dioxide requires 24 electrons, while the synthesis of the amino acid cysteine requires as many as 26 electrons per molecule of amino acid ... 

The amide functionality plays an important role in the physical and chemical properties of proteins and peptides, especially in their ability to be involved in the photoinduced electron transfer process. Polyamides and proteins are known to take part in the biological electron transport mechanism for oxidation-reduction and photosynthesis processes. Therefore studies of the photochemistry of proteins or peptides are very important. Irradiation (at 254 nm) of the simplest dipeptide, glycylglycine, in aqueous solution affords carbon dioxide, ammonia and acetamide in relatively high yields and quantum yield (0.44)202 (equation 147). The reaction mechanism is thought to involve an electron transfer process. The isolation of intermediates such as IV-hydroxymethylacetamide and 7V-glycylglycyl-methyl acetamide confirmed the electron-transfer initiated free radical processes203 (equation 148). 

Because the organic chemicals are destroyed in the GPCR reactor by reduction reactions, the main products are gases such as methane, carbon monoxide, and carbon dioxide. These gases, plus the excess feed hydrogen, must be removed at a controlled rate to maintain the set system pressure fluctuations in the system pressure are undesirable and may lead to process upsets. To accommodate the fluctuating reactor loading and gas production, the compressor must be controlled to remove gas from the system at a variable rate. This is accomplished with a variable-speed drive on the compressor. 

Combustion is an oxidation-reduction reaction between a nonmetallic material and molecular oxygen. Combustion reactions are characteristically exothermic (energy releasing). A violent combustion reaction is the formation of water from hydrogen and oxygen. As discussed in Section 9.5, the energy from this reaction is used to power rockets into space. More common examples of combustion include the burning of wood and fossil fuels. The combustion of these and other carbon-based chemicals forms carbon dioxide and water. Consider, for example, the combustion of methane, the major component of natural gas ... 

Reasons for interest in the catalyzed reactions of NO, CO, and COz are many and varied. Nitric oxide, for example, is an odd electron, hetero-nuclear diatomic which is the parent member of the environmentally hazardous oxides of nitrogen. Its decomposition and reduction reactions, which occur only in the presence of catalysts, provide a stimulus to research in nitrosyl chemistry. From a different perspective, the catalyzed reactions of CO and COz have attracted attention because of the need to develop hydrocarbon sources that are alternatives to petroleum. Carbon dioxide is one of the most abundant sources of carbon available, but its utilization will require a cheap and plentiful source of hydrogen for reduction, and the development of catalysts that will permit reduction to take place under mild conditions. The use of carbon monoxide in the development of alternative hydrocarbon sources is better defined at this time, being directly linked to coal utilization. The conversion of coal to substitute natural gas (SNG), hydrocarbons, and organic chemicals is based on the hydrogen reduction of CO via methanation and the Fischer-Tropsch synthesis. Notable successes using heterogeneous catalysts have been achieved in this area, but most mechanistic proposals remain unproven, and overall efficiencies can still be improved. 

---