Boudouard-equilibrium

Material 2 syringes, quartz reaction tube, two burners, gas tracing instrument (Draeger tubes for CO), small beakers carbon pieces, glass wool, carbon dioxide (lecture bottle), limewater. 

Observation The highest possible volume of 100 ml is not reached - a constant volume of about 60 ml can be measured. The test tube shows the presence of carbon monoxide, limewater also proves the presence of carbon dioxide. 

Tip Calculations with the aid of the initial and final volume lead to the equilibrium volume of 40 ml C02 and 20ml CO, the comparison of volume 

Material Gas generator, two syringes, two quartz combustion tubes, burner, small gas jar with glass cover, glass bowl concentrated ammonia solution, sodium hydroxide, pieces of nickel wire, copper oxide (wire form), wood splint. 

Observation (a) From 50 ml gaseous ammonia, 100 ml colorless gas is formed mixture of hydrogen and nitrogen, (b) By leading the gas mixture over heated black copper oxide, red-brown shiny copper is formed condensation of water is observed, approximately 25 ml of gas remains. This gas immediately extinguishes the flames of the burning wood splint nitrogen. 

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From 860 to 980 °C, the carbon monoxide yield increases from near zero to about 50%, while the carbon dioxide yield decreases from about 30 to 15% [2]. This shift is according to the Boudouard equilibrium. 

The first reaction (Boudouard equilibrium) favors carbon formation at lower temperatures compared to POX. The hydrogen concentrations attained depend on the fuel used in POX but it never reaches the theoretical level [27],... 

Boudouard equilibrium 322 337 boullies = slurries 289 368 bourrage = stemming 299 bourrage a I eau = water stemming 369... 

For low caloric propellants and for highly negative balanced explosives, such as TNT, the formation of element carbon must be assumed (.Boudouard equilibrium) ... 

Boudouard-Equilibrium Water-Gas Equilibrium Methanizing reactions... 

Boudouard Equilibrium. Equilibria can be well demonstrated when gases are involved. Carbon is used to reduce iron oxide minerals for the production of iron metal in a blast furnace. However, carbon itself barely functions as a means of reduction but rather the carbon monoxide, CO. It results in a reaction of gaseous carbon dioxide with glowing carbon by a temperature of approximately 1000°C ... 

If one refers to the temperature-volume diagram of the Boudouard equilibrium (see Fig. 6.7), one recognizes that the attained equilibrium exists at about 650°C, a temperature that can easily be produced with a good burner. One also recognizes that, at higher temperatures, the amount of carbon monoxide at equilibrium increases a lot and that the position of the equilibrium varies with the temperature. 

Equilibrium Constant. The position of the C02/CO equilibrium can be explained with the help of the equilibrium constant, using either the partial pressures or concentrations of both gases. In none of the cases the solid carbon is considered in the Boudouard equilibrium it neither adds to the complete pressure, nor does it allow a concentration to be specified. 

Summary. The discussed equilibria show, in the cases in which the concentrations of the reaction partners are measured, that these concentrations are not inevitably the same as students assume (see Sect. 6.1). For the Boudouard equilibrium, completely different pairs of values are possible (see Fig. 6.7). The same applies for the hydrogen-iodine example (see Figs. 6.8 and 6.9) and for the ammonia example (see Fig. 6.10). 

The Boudouard equilibrium also shows that the excess of solid matter does not play any role how much carbon is used or which part of the carbon pieces are heated is irrelevant. Even in the furnace process, neither the amount of coal mixed into the iron ore nor how full the furnace is affects the position of the equilibrium. In order to have an optimal reaction, though, it is only necessary to have an excess of coal. 

BaS is leached from the black ash by hot water. The resulting solution is filtered and then treated with soda ash or carbon dioxide or a combination of the two to precipitate fine BaC03 crystals, which in turn are filtered and dried. Sulfide values can be recovered as H2S, NaHS, Na2S, or elemental sulfur. Carbon dioxide, detrimental to high BaS yields, is repressed according to the Boudouard equilibrium... 

The preparation of single-walled nanotubes succeeds more easily by the so-called HiPCo-process that was published for the first time in 1998. The name is deduced from high-pressure carbon monoxide and signifies a crucial aspect of the method Here the carbon source is not a hydrocarbon, but carbon monoxide that does not suffer pyrolysis at the relevant temperatures. The formation of carbon material is based on the Boudouard equilibrium (3.9) ... 

Fig. 7.3 Predominance area diagram for the system Zn-O-C. The line for the Boudouard equilibrium crosses the coexistence line for ZnO/Zn (gas) at the point A at unit pressures of CO and Zn (gas). When 7" > then ZnO can be reduced to Zn using solid carbon.

The electrode potential curve for the equilibrum of pure carbon and a pure C0,C02 mixture (Boudouard-Equilibrium) at a total pressure p is shown in Figure 25-1. This is the border line of all electrode potential curves of pure COfZO mixtures. The plot is linear at low and high temperatures, because the concentration of either CO in comparison to COj or vice-versa can be ignored. In the limiting cases there are the equilibria... 

An interesting way of generating solar fuels can be seen in two classical inorganic carbon carriers CO and carbon itself. The gasification of carbon (2.154a) produces CO (generator gas) in the so-called Boudouard equilibrium ... 

The individual contributions of reactions (1) and (2) in reaction (3) at higher pressures (100 MPa) are strongly temperature dependent (Fig. 2). It is clear that the equilibrium amounts run in pairs CH4 + CO2, Cdiamond + H2O, and CO -I- H2. The deviation at higher temperatures stems from the influence of the Boudouard equilibrium... 

The process is carried out in huge electric arc or resistance furnaces and is comparable to the Acheson process. The reaction takes place between 1500 and 2500°C, is strongly endothermic and requires 1812kJ/mol, i.e., 9.1 kWh/kg [159, 160]. Since large quantities of carbon monoxide (approximately 2.3m /kg) are formed, the reaction of Eq. (2) is accelerated to the benefit of B4C. Both volatilized boron oxides and carbon monoxide generate an internal Boudouard equilibrium within the raw material mixture and thus contribute to a self-propagating purification process, which can be expressed by... 

The steam rate is appropriately set to ensure a difference of 100 to 120 °C between the reactor outlet temperature and the Boudouard equilibrium temperature. In addition to its moderating effect upon combustion in the initial combustion zone, the steam will then also safely prevent soot formation in the reaction zone and tends to reduce the residual methane content. The oxygen demand may be calculated from the system heat demand. 

Although under the conditions prevailing in the reaction zone, neither the Boudouard equilibrium nor the heterogeneous water gas reaction would justify soot formation, flee carbon is produced together with the reformed gas at a rate of O.S-2wt % in terms of the feedstock, depending on the temperature and the quantity of steam added, but also on the retention time. When the soot is recycled together with the feedstock, the soot content in the reformed gas does... 

At the same time, it must be remembered that at temperatures above 750°C, the so-called Boudouard equilibrium is established ... 

As an example, we shall examine the ease of the Boudouard equilibrium for reaction [3R.25] between monoxide, carbon dioxide and... 

Under the conditions of partial oxidation, carbon should not be present according to the Boudouard equilibrium [Eq. (6.2.6)], but nevertheless soot can be present in the raw gas. During partial oxidation of methane soot formation is practically zero, whereas in heavy-oil gasification of up to 4% by mass of feedstock is converted into soot. 

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