Carbon Dioxide in the Gas Phase

C02 in the gas phase can be determined by means of its significant infrared absorbance (Fig. 10) at wave lengths (A) 15 pm, particularly at 4.3 pm [289], or by acoustic means. Integrated photoacoustic spectroscopy and magnetoacoustic (PAS/MA) technology for combined C02 and 02 analysis has rapid response time and a small sample volume is sufficient. The acoustic methods are accurate, stable over long periods and very simple to use. 

---

The factor a has been estimated by measuring the concentration of carbon dioxide in the gas phase and in the film at equilibrium. 

A carbon particle is large enough so that the burning rate is diffusion-controlled. In one case the carbon monoxide leaving the surface bums to carbon dioxide in the gas phase in another, no further carbon monoxide... 

An alternative method of suppressing carbonate decomposition is possible because the decomposition pressure of calcium carbonate is low enough to be overcome by a trace of carbon dioxide in the gas phase. When 2% carbon dioxide was added to the feed gas (10-psia carbon dioxide), the carbonate decomposition was much less than in the corresponding pure hydrogen runs. 

The carbonic acid, which in (6) comes to equilibrium with the carbon dioxide in the gas phase, is in this experiment neutralized by the base,... 

Gas Composition. To remove the restriction of constant dissolved carbon dioxide concentration, it is necessary to consider the interactions between the gas and liquid phases of the reactor. At equilibrium the dissolved carbon dioxide concentration can be related to the partial pressure of carbon dioxide in the gas phase by Henry s law as shown in Equation 23. 

A material balance must also be made on the carbon dioxide in the gas phase to calculate the partial pressure of carbon dioxide for use in Henrys law. This is given (assuming complete mixing) in Equation 29. 

The units in which the carbon dioxide in the gas phase are expressed, moles C02/liter of reactor gas volume, can be converted to a partial pressure of carbon dioxide by using Equation 30. 

Process failure by organic overloading was simulated by a sudden or step change in So from 167 to 667 mmoles/liter, and the results are shown in Figures llA and IIB. The volatile acids concentration and percentage of carbon dioxide in the gas phase both increase and the bicarbonate alkalinity and pH both decrease in a manner similar to that... 

Calorimetric data indeed confirm this interaction (66). Since the adsorption of carbon dioxide does not modify the electrical conductivity of the oxygen-precovered sample, it does not seem that a bivalent carbonate species [COj fads)] is formed. Moreover, the reactivity toward carbon monoxide of the products of interactions (5a) or (8) between preadsorbed carbon monoxide and oxygen or between preadsorbed oxygen and carbon dioxide, being identical, we believe that, in both cases, the same surface species C08-(ads) is formed. During the catalytic reaction, however, interaction between adsorbed oxygen and gaseous carbon dioxide is unimportant since all carbon dioxide in the gas phase is condensed in a cold trap placed near the catalyst. 

Ross and co-workers [9,10] have explored the influence of CO2 on the oxidative coupling of methane over the Li/MgO catalyst. They found that carbon dioxide in the gas phase lowers both the methane conversion and the yield of ethane/ethylene products. They also found that carbon dioxide significantly improves the stability of the catalyst against deactivation. Based on the observations of surface species from FTIRS and transient experiments. In addition, most of the observations and experimental results reported to date cover a limited range of methane to oxygen feed ratios. There is a need to study the reaction over a wide range of methane to oxygen ratios and to quantify the effects of carbon dioxide on the reaction rates. 

Ammonium carbamate has been prepared by the direct combination of ammonia and carbon dioxide in the gas phase and also in cooled inert solvents such as absolute alcohol and petroleum ether. The direct laboratory preparation from readily available Dry Ice and liquid ammonia offers a convenient source of ammonium carbamate. It is interesting to note that under other conditions these same reactants produce urea. 

The term sweet is commonly applied to petroleum production environments containing carbon dioxide (CO2) tind no hydrogen sulfide. These environments tire genertdly defined for corrosion purposes on the basis of the partial pressure of carbon dioxide in the gas phase. This grossly defines the level of dissolved CO2 in the water phase and, according to mjiny sources, roughly defines the relative aggressiveness of the water pheise. 

Davies stressed the importance of an adequate supply of carbon dioxide for optimal secretion for the reason that some investigators, notably myself, performed similar experiments in which tied sacs of mucosa were incubated in phosphate-buffered salt solution with no carbon dioxide in the gas phase. Davies allowed that in such an experimental situation, carbon dioxide produced by the tissue s metabolism could be recycled so that phosphate could become the ultimate determinant of the oxyntic cells internal neutrality, but he repeatedly asserted that the gastric mucosa does not secrete acid at its maximal rate in the absence of exogenous carbon dioxide. 

Another new development in the use of hydrogen as a fuel is in the fuel cell car developed by Daimler-Chrysler, the NECAR. This prototype electric car uses hydrogen as a fuel for a fuel cell in which the energy of hydrogen oxidation to water is converted to electricity. The car runs on a mixture of methanol and water. Using a relatively low-temperature catalyst, these substances react to produce hydrogen and carbon dioxide, in the gas phase ... 

---