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| The '''Boudouard reaction''', named after [[Octave Leopold Boudouard]], is the [[redox]] reaction of a [[chemical equilibrium]] mixture of [[carbon monoxide]] and [[carbon dioxide]] at a given temperature. It is the [[disproportionation]] of carbon monoxide into carbon dioxide and [[graphite]] or its reverse:<ref>[http://gasifiers.bioenergylists.org/files/Boudouard%20Reaction.xls Bioenergylist.org – Boudouard Reaction spreadsheet]</ref> | | The author is called Irwin Wunder but it's not the most masucline title out there. North Dakota is where me and my spouse live. To collect cash is a thing that I'm totally addicted to. Managing people is what I do and the wage has been really fulfilling.<br><br>Here is my site std testing at home; [http://www.ddaybeauty.com/node/14766 simply click for source], |
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| <div align="center"><math>2CO \rightleftharpoons CO_2 + C</math></div>
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| [[File:DeltaH for Boudouard Reaction by Temperature.png|thumb|Standard enthalpy of the Boudouard reaction at various temperatures]]
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| The Boudouard Reaction to form carbon dioxide and carbon is [[exothermic]] at all temperatures. However, the [[enthalpy#Heat of reaction|standard enthalpy]] of the Boudouard reaction becomes less negative with increasing temperature,<ref name="ReacWeb">[http://www.crct.polymtl.ca/reacweb.htm Reaction Web]</ref> as shown to the side.
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| While the [[formation enthalpy]] of {{chem|CO|2}} is higher than that of {{chem|CO}}, the formation entropy is much lower. Consequently, the standard [[Gibbs free energy|free energy of formation]] of {{chem|CO|2}} from its component elements is almost constant and independent of the temperature, while the free energy of formation of {{chem|CO}} decreases with temperature.<ref>[[List of standard Gibbs free energies of formation]]</ref> At high temperatures, the forward reaction is therefore [[endergonic]], favoring the ([[exergonic]]) reverse reaction toward CO, even though the forward reaction is still [[exothermic]].
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| The effect of temperature on the extent of the Boudouard reaction is indicated better by the value of the [[equilibrium constant]] than by the standard [[Gibbs free energy#Free energy of reactions|free energy of reaction]]. The value of log(K<sub>eq</sub>) for the reaction (valid between 500–{{val|fmt=commas|2200|ul= K}}) is:<ref name="ReacWeb" />
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| <div align="center"><math>Log(K_{eq}) = \frac{9141}{T} + 0.000224T - 9.595</math></div>
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| Log(K<sub>eq</sub>) has a value of zero at {{val|975|ul=K}}.
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| The implication of the change in K<sub>eq</sub> with temperature is that a gas containing {{chem|CO}} and {{chem|CO|2}} may form elemental carbon if the mixture cools below a certain temperature. The thermodynamic activity of carbon may be calculated for a {{chem|CO}}/{{chem|CO|2}} mixture by knowing the partial pressure of each species and the value of K<sub>eq</sub>. For instance, in a high temperature reducing environment, such as that created for the [[Direct reduced iron|reduction of iron oxide]] in a [[Blast furnace#Process engineering and chemistry|blast furnace]] or the preparation of [[carburizing]] atmospheres,<ref>ASM Committee on Furnace Atmospheres, [http://openlibrary.org/books/OL5930494M/Furnace_atmospheres_and_carbon_control ''Furnace atmospheres and carbon control''], Metals Park, OH [1964].</ref> carbon monoxide is the stable oxide of carbon. When a gas rich in {{chem|CO}} is cooled to the point where the activity of carbon exceeds one, the Boudouard Reaction can take place. Carbon monoxide then tends to disproportionate into carbon dioxide and graphite, which forms [[soot]].
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| In industrial [[catalysis]], this is not just an eyesore; sooting (also called coking) can cause serious and even irreversible damage to catalysts and catalyst beds. This is a problem in the [[Catalytic reforming|catalytic reforming of petroleum]] and the [[Steam reforming|steam reforming of natural gas]].
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| The reaction is named after the French chemist, [[Octave Leopold Boudouard]] (1872–1923), who investigated this equilibrium in 1905.<ref name="InorganicChem">{{cite book | last1 = Holleman | first1 = Arnold F. | last2 = Wiber | first2 = Egon | last3 = Wiberg | first3 = Nils |title = Inorganic Chemistry | url = http://books.google.com/books?id=vEwj1WZKThEC&pg=PA810 | accessdate = 12 July 2013 | year = 2001 | publisher = Academic Press | isbn = 978-0-12-352651-9 | page = 810 }}</ref>
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| == Uses ==
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| Although the damaging effect of [[carbon monoxide]] on catalysts is undesirable, this reaction has been used in producing [[graphite]] flakes, filamentous graphite and lamellar graphite crystallites, as well as producing [[carbon nanotubes]].<ref name="Graphite1">{{cite journal | last = Baird | first = T. | last2 = Fryer | first2 = J. R. | last3 = Grant | first3 = B.| year = Oct 1974 | title = Carbon | contribution = Carbon formation on iron and nickel foils by hydrocarbon pyrolysis—reactions at 700°C | volume = 12 | pages = 591–602 | url = http://www.sciencedirect.com/science/article/pii/0008622374900608 | doi = 10.1016/0008-6223(74)90060-8}}</ref><ref name="Graphite2">{{cite journal | last = Trimm | first = D. L. | year = 1977 | title = Catalysis Reviews: Science and Engineering | contribution = The formation and removal of coke from nickel catalyst | volume = 16 | pages = 155–189 | url = http://www.tandfonline.com/doi/abs/10.1080/03602457708079636#.UeRDyI2PMm0 | doi = 10.1080/03602457708079636}}</ref><ref name="CNT1">{{cite journal | last = Dal | first = H. J. | last2 = Rinzler | first2 = A. G. | last3 = Nikolaev | first3 = P. | last4 = Thess | first4 = A. | last5 = Colbert | first5 = D. T. | last6 = Smalley | first6 = R. E. | year = 1996 | title = Chem. Phys. Lett. | contribution = Single-wall nanotubes produced by metal-catalyzed disproportionation of carbon monoxide | volume = 260 | pages = 471–475 }}</ref><ref name="CNT2">{{cite journal | last = Chen | first = P. | last2 = Zhang | first2 = H. B. | last3 = Lin | first3 = G. D. | last4 = Hong | first4 = Q. | last5 = Tsai | first5 = K. R. | year = 1997 | title = Carbon | contribution = Growth of carbon nanotubes by catalytic decomposition of CH<sub>4</sub> or CO on a Ni-MgO catalyst | volume = 35 | pages = 1495–1501 | url = http://www.sciencedirect.com/science/article/pii/S0008622397001000 | doi = 10.1016/S0008-6223(97)00100-0}}</ref> In graphite production, catalysts used are [[molybdenum]], [[magnesium]], [[nickel]], [[iron]] and [[cobalt]],<ref name="Graphite1"/><ref name="Graphite2"/> while in carbon nanotube production, [[molybdenum]], [[nickel]], [[cobalt]], [[iron]] and Ni-MgO catalysts are used.<ref name="CNT1"/><ref name="CNT2"/>
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| The Boudouard reaction is an important process inside a [[blast furnace]]. The reduction of iron oxides is not achieved by carbon directly, as reactions between solids are typically very slow, but by carbon monoxide. The resulting carbon dioxide undergoes a Boudouard reaction upon contact with [[Coke (fuel)|coke]] carbon.
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| == References ==
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| {{Reflist}}
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| ==External links==
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| {{cite web | last = Robinson | first = R. J. | authorlink = | title = Boudouard Process for Synthesis Gas | work = | publisher = ABC of Alternative Energy | url = http://www.abc-alternative-energy.de/bioenergy/boudouard-process.html | accessdate = 12 July 2013 }}
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| [[Category:Carbon-heteroatom bond forming reactions]]
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| [[Category:Name reactions]]
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