Trapping of carbon dioxide

Saylor, B. Zerai, B. 2004. Injection and trapping of carbon dioxide in deep saline aquifers. In Giere, R. Stille, P. (eds). Energy, Waste, and the Environment a Geochemical Perspective. Geological Society, London, Special Publications, 236, 285-296. 

Injection and trapping of carbon dioxide in deep saline aquifers... 

Basalts are also widely distributed in nature. Commonly, they have low porosity, low permeability and low pore space continuity. These properties do not bode well for gas storage. Nonetheless, basalt may have some potential for the permanent mineral trapping of carbon dioxide, because the gas may react with silicates in the matrix to form carbonate minerals. This requires further investigation. 

The carbon dioxide needed for this step enters through pores in the photosynthetic leaf (called stromata). Plants close these pores during hot, dry times of the day (to prevent water loss) so the details of carbon fixing vary for plants from different climates. In hot climates, where stomata are closed for a higher percentage of time, the trapping of carbon dioxide has to be more efficient than in cooler climates. This biochemical difference in photosynthesis helps explain why plants from one climate do not grow as well in warmer (or cooler) places. 

The most overlooked hazard and contaminant is water (99). Water reacts with isocyanates at room temperature to yield both ureas and large quantities of carbon dioxide. The presence of water or moisture can produce a sufficient amount of CO2 to overpressurize and mpture containers. As Httle as 30 mL of water can result in 40 L of carbon dioxide which could result in pressures of up to 300 kPa (40 psi). For these reasons, the use of dry nitrogen atmospheres is recommended during handling. If a plant air system must be used, purification equipment, such as oil traps and drying beds, should be installed between the source and the isocyanate vessel. 

Another requirement for proper leavening is the presence of a protein matrix sufftciendy elastic to trap small carbon dioxide bubbles. Wheat gluten fulfills this requirement. Rye protein is less suitable and the proteins of other cereals, eg, rice, oats, or com, are practically useless. 

In the case of carbanion and radical intermediates the solvent is less important but the products are partially determined by the resistance of the medium to proton or hydrogen atom abstraction respectively. The increased stability of these intermediates compared with carbonium ions allows the reaction mechanism to be more readily modified by the addition of trapping agents. For example, carbanions are trapped in high yields by the presence of carbon dioxide in the electrolysis medium (Wawzonek and Wearring, 1959 Wawzonek et al., 1955). 

Problems may arise when the atmospheric concentration of greenhouse gases increases. Since the beginning of the industrial revolution, atmospheric concentrations of carbon dioxide have increased nearly 30%, methane concentrations have more than doubled, and nitrous oxide concentrations have risen by about 15%. These increases have enhanced the heat-trapping capability of the earth s atmosphere. 

Use of a steel chisel to open a drum of carbide caused an incendive spark which ignited traces of acetylene in the drum. The non-ferrous tools normally used for this purpose should be kept free from embedded ferrous particles [1], If calcium carbide is warm when filled into drums, absorption of the nitrogen from the trapped air may enrich the oxygen content up to 28%. In this case, less than 3% of acetylene (liberated by moisture) is enough to form an explosive mixture, which may be initiated on opening the sealed drum. Other precautions are detailed [2], Use of carbon dioxide to purge carbide drums, and of brass or bronze non-sparking tools to open them are advocated [3],... 

Equation (44) has indeed been confirmed by electrical conductivity measurements and by the detection of carbon dioxide condensed in the cold trap (53). 

The photoelimination of carbon dioxide from esters and lactones is a process that has been the subject of detailed investigations. Discussion here is limited to nitrogen containing systems. 3,4-Diphenylsydnone (464), on irradiation in benzene, is converted via the nitrile imine 465 into 2,4,5-triphenyl-1,2,3-triazole (466)388 initial bond formation between N-2 and C-4 followed by loss of carbon dioxide to give the diazirine 467 is proposed to account for the formation of the nitrile imine. Nitrile imines generated in this way have been trapped with alkenes and alkynes to give pyrazoles389... 

A full understanding will be needed of the complex chemistry by which the atmosphere and the earth interact, including the dependence of global climate on carbon dioxide concentrations in the atmosphere. Is there a way to deal with the carbon dioxide produced by burning coal and other hydrocarbon fuels so that it causes no problem Chemical scientists will need to investigate effective ways to trap C02 that would otherwise build up in the atmosphere. Alternatively, it will be necessary to find ways to reduce the generation of carbon dioxide. As human... 

A) 2-Bromophthalide.—The apparatus shown in Fig. 6 is used for the bromination. Flasks A and B are of 200-cc. capacity. Bromine is introduced by means of a current of carbon dioxide, which passes through mineral oil or sulfuric acid in the bubble counter, then through the bromine in flask B, and finally through the drying tower. The tower is conveniently made from a condenser jacket and is filled with anhydrous calcium chloride. Flask A is surrounded by an oil bath and is equipped with a thermometer, an outlet tube of wide bore connected to a gas absorption trap, and a gas inlet tube having an inside diameter of 2 mm. The inlet tube reaches to the bottom of the flask. 

One of the changes that happens during the dough development stage is that the dough traps the carbon dioxide. 

Hydrogenation of carbon dioxide in the presence of an epoxide generates a mixture of the diol, its formate esters, and the cyclic carbonate. While the reaction has been shown to operate in high yield (1300 TON for the cyclic carbonate Eq. (10)) [93], the fact that a mixture is generated and that the cyclic carbonate could be made more cleanly in the absence of H2 makes the reaction uninteresting for synthesis. Sasaki s group showed that this reaction in the presence of an amine base gives CO rather than cyclic carbonate (Eq. (11)) [94]. The epoxide then serves as a trap for the water. 

Since the calcium chloride contains basic constituents the filling must be saturated with carbon dioxide before the absorption tube is used. For this purpose connect the side tube which leads to the water trap to the Kipp apparatus, interposing a drying tube, pass a strong current of carbon dioxide for 10 minutes, close the outlet, and allow to stand for half an hour, maintaining the pressure of the Kipp. After 200 c.c. of dry air have been drawn through the tube by means of the aspirator, the tube is ready for use. 

DBU = l,8-diazabicyclo[5.4.0]undec-7-ene (15) is a nonnucleophilic base employed in conjunction with piperidine in dimethylformamide (1 1 48) for removal of fluorenylmethyl-based protectors. The piperidine is necessary as a nucleophile to trap the expelled moiety that does not react with DBU. DBU has no effect on phthalimido [Pth-NH of -Lys(Pht)-], dialky-lphosphoryl [-Tyr(P03R2)-], or Dde-NH [-Lys(Dde)- see Section 6.4], but it promotes aspartimide formation at the pertinent residues of susceptible sequences (see Section 6.13). In dichloromethane, it promotes a reaction between two molecules of urethane-protected amino acid /V-carboxyanhy-dride with release of carbon dioxide (see Section 7.14). 

Further data from the polarography and cyclic voltammetry in dimethylformamide are given in Table 5.1 for a series of overall two-electron processes leading to cleavage of a benzyl-heteroatom bond. The first electron transfer step is of the dissociative electron transfer type leading to a benzyl radical. This radical is reduced firrther, at the working potential, to the benzyl carbanion. The carbanion fi om benzyl chlorides, esters, ethers, sulphides, sulphones and quaternary ammonium salts can be trapped by carbon dioxide to form phenylacetic acid [2]. Reac-... 

Wawzonek [47] first noted that the radical-anion from benzophenone can be trapped by carbon dioxide in dimethylformamide to yield benzilic acid. The radical-anion of carbon dioxide has E° = - 2.2 V vs. see [48] and will not be formed in... 

Anhydro-5-hydroxy-1,2,3,4-oxatriazolium hydroxides (4) are relatively stable at elevated temperatures under neutral and salt-free conditions. However, prolonged heating of (17) in the presence of lithium chloride gives rise to elimination of carbon dioxide with formation of an azide which can be trapped by 1,3-dipolar cycloaddition to an alkyne (Scheme 2) <68CB536>. 

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