Carbon dioxide with ethanolamines

SolubiHty of carbon dioxide in ethanolamines is affected by temperature, amine solution strength, and carbon dioxide partial pressure. Information on the performance of amines is available in the Hterature and from amine manufacturers. Values for the solubiHty of carbon dioxide and hydrogen sulfide mixtures in monoethanolamine and for the solubiHty of carbon dioxide in diethanolamine are given (36,37). SolubiHty of carbon dioxide in monoethanolamine is provided (38). The effects of catalysts have been studied to improve the activity of amines and provide absorption data for carbon dioxide in both mono- and diethanolamine solutions with and without sodium arsenite as a catalyst (39). Absorption kinetics over a range of contact times for carbon dioxide in monoethanolamine have also been investigated (40). 

One of the principal aspects of refinery gas cleanup is the removal of acid gas constituents, ie, carbon dioxide, CO2, and hydrogen sulfide, H2S. Treatment of natural gas to remove the acid gas constituents is most often accompHshed by contacting the natural gas with an alkaline solution. The most commonly used treating solutions are aqueous solutions of the ethanolamines or alkah carbonates. There are several hydrogen sulfide removal processes (29), most of which are followed by a Claus plant that produces elemental sulfur from the hydrogen sulfide. 

The carbon dioxide emission has been quantified using the apparatus shown in Figure 1. Under controlled conditions of temperature and relative humidity the emitted carbon dioxide was continuously trapped in a solution of ethanolamine in dimethylformamide (11) and titrated continuously to a preset potential with tetrabutylammonlum hydroxyde in isopropanol. 

Procedures are reported for the synthesis of ethyleneurea from ethylene glycol or ethanolamine either with urea or with ammonia and carbon dioxide. Pressure and other variables affecting the reactions are discussed and a mechanism is suggested by which amination of the carbon skeleton takes place. 

Carbon dioxide, 4 an important green house gas,45 is obtained in combustion of carbon and hydrocarbons, calcination of CaC03, and so on. It forms complexes with transition metals (Section 7-14) and inserts into MH and other bonds (Section 21-3). The gas is very soluble in ethanolamines, which are used to scrub C02 from gas streams. Liquid C02 at pressures up to 400 bar is a solvent for some organic compounds and is used to extract caffeine from coffee beans many studies of other applications of supercritical C02 have been conducted.46... 

The aromatic polyimides, cited earlier, separate carbon dioxide over methane with a-valves of 150-160. Aromatic polyoxadiazoles have a-valves of 100-2 00.157 The permeability of one aromatic polyimide was improved by two to four orders of magnitude by carbonizing it on porous alumina,158 the final a-valve being 100. In this case, the final actual membrane was probably a porous carbon molecular sieve. Facilitated transport has also been used to increase the separation factor. A porous poly(vinylidene difluoride) membrane with ethanolamine or diethanolamine in the pores gave a separation factor of carbon dioxide over methane of 2000.159 Such a method is less energy-intensive than when an amine is used in the usual solvent method. 

In earlier work [14] a chemical method was proposed for concentrating trace amounts of carbon dioxide and hydrogen sulphide, based on the ability of substances with acidic properties to form unstable compounds with organic bases, such as ethanolamines, at room temperature. As the temperature is increased, these compounds readily dissociate into the starting components, and the concentrated zone of acidic gaseous trace components is separated into individual components in the chromatographic column. 

Separation of carbon dioxide from combustion products by absorption with aqueous solutions of an ethanolamine (Vol. 4, p. 358, 362)... 

With reference to row 6 in Tabie 1.1, for example, describe a separation process based on an operation other than absorption in ethanolamine to separate carbon dioxide from combustion products.)... 

The carbon dioxide may then be. removed by scrubbing with caustic solutions or, preferably, with amines such as ethanolamines. 

Measure 50 ml of the water sample into each of two 250-ml beakers (if concentration < 10 mg/1 Ca2+ use correspondingly more evaporate to 50 ml) and acidify with perchloric acid (2) (pH 2 - 3). Boil until the carbon dioxide is expelled, and when cool treat with 10 ml of masking solution. Leave the samples to stand for 10 minutes, then add 1 ml of triethanolamine solution and adjust to pH 10.5 with ethanolamine solution (thereby prevent-... 

The presence of carbon dioxide or hydrogen sulphide has no influence on the corrosion resistance of aluminium in ethanolamine solutions. Gas desulphurisation plants have been built with heat exchangers in 3003 [4],... 

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