Monoethanolamine dioxide

For example, hydrogen sulfide and carbon dioxide can be removed from natural gas by reaction with monoethanolamine in an absorber according to the following reactions ... 

These reactions can be reversed in a distillation column. This releases the hydrogen sulfide and carbon dioxide for further processing. The monoethanolamine can then be recycled. 

A.lkanolamine Process. Carbon dioxide is an acidic gas that reacts reversibly with aqueous alkaline solution to form a carbonate adduct. This adduct decomposes upon the addition of low level heat faciUtating CO2 removal. An aqueous solution of 15—20 wt % monoethanolamine (MEA) was the standard method for removing CO2 in early ammonia plants. 

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). 

Direct hydrogen cyanide (HCN) gas in a fuel oil gasification plant to a combustion unit to prevent its release. 4. Consider using purge gases from the synthesis process to fire the reformer strip condensates to reduce ammonia and methanol. 5. Use carbon dioxide removal processes that do not release toxics to the environment. When monoethanolamine (MEA) or other processes, such as hot potassium carbonate, are used in carbon dioxide removal, proper operation and maintenance procedures should be followed to minimize releases to the environment. 

Closed drain headers are normally provided for safe drainage of equipment containing severely toxic, corrosive, pollutant or high cost chemicals (e.g., phenol, sulfuric acid, monoethanolamine, sulfur dioxide, catacarb) where there is an appreciable inventory in a number of processing vessels in a plant. The header should be at least 50 mm in diameter, and should be tied into the major vessels and equipment with 25 mm minimum size connections (20 mm is considered adequate for pumps). The header may be routed to a gravity drain drum (with recovery to the process by pump or gas pressurization), or to a pumpout pump returning to the process, or in the case of sulfuric acid, to an acid blowdown drum. 

Emmert and Pigford (E2) have studied the reaction between carbon dioxide and aqueous solutions of monoethanolamine (MEA) and report that the reaction rate constant is 5400 liter/mole sec at 25°C. If it is assumed that MEA is present in excess, the reaction may be treated as pseudo first-order. This pseudo first-order reaction has been recently used by Johnson et al. (J4) to study the rate of absorption from single carbon dioxide bubbles under forced convection conditions, and the results were compared with their theoretical model. 

An attempt has been made by Johnson and co-workers to relate such theoretical results with experimental data for the absorption of a single carbon dioxide bubble into aqueous solutions of monoethanolamine, determined under forced convection conditions over a Reynolds number range from 30 to 220. The numerical results were found to be much higher than the measured values for noncirculating bubbles. The numerical solutions indicate that the mass-transfer rate should be independent of Peclet number, whereas the experimentally measured rates increase gradually with increasing Peclet number. The discrepancy is attributed to the experimental technique, where-... 

The hydrogen is separated from the carbon dioxide by contacting the mixture with a liquid chemical (monoethanolamine), which absorbs the carbon dioxide. The latter can be recovered in high purity from the monoethanolamine. 

Examples of reversible reactions are the removal of hydrogen sulfide and carbon dioxide from gas streams using a solution of monoethanolamine ... 

Econamine FG [Flue gas] A process for removing carbon dioxide from flue-gases by dissolution in an aqueous solution of monoethanolamine and a proprietary corrosion inhibitor. Originally developed by the Dow Chemical Company under the designation Gas/Spec FT, the process was acquired in 1989 by the Fluor Corporation and is now licensed by that company. 

Experiments involving the release of radioactive carbon dioxide from MSMA-14C treated soils were conducted in a system consisting of two test tubes connected in series. One tube contained 5g of treated soil (at 10 and lOOppm of monosodium methane arsenic acid carbon dioxide while a second tube contained a trapping mixture, 2-methoxyethanol and monoethanolamine (7-10, v/v). Carbon dioxide-free air was passed over the soil and metabolic 14CO was collected in the trapping solution. The soils studied were Sharkey cldy, Hagerstown silty clay loam, Cecil sandy loam, and Dundee silty clay loam. All soils were initially adjusted to field capacity and maintained at 28-30°C the evolved 14CO was sampled periodically. Some properties of these soils are shown in Tabfe 13.1. 

In many of these experiments, interfacial turbulence was the obvious visible cause of the unusual features of the rate of mass transfer. There are, however, experimental results in which no interfacial activity was observed. Brian et al. [108] have drawn attention to the severe disagreement existing between the penetration theory and data for the absorption of carbon dioxide in monoethanolamine. They have performed experiments on the absorption of C02 with simultaneous desorption of propylene in a short, wetted wall column. The desorption of propylene without absorption of C02 agrees closely with the predictions of the penetration theory. If, however, both processes take place simultaneously, the rate of desorption is greatly increased. This enhancement must be linked to a hydrodynamic effect induced by the absorption of C02 and the only one which can occur appears to be the interfacial turbulence caused by the Marangoni effect. No interfacial activity was observed because of the small scale and small intensity of the induced turbulence. 

Alkanolamines. Gas sweetening, ie, removal of hydrogen sulfide and carbon dioxide, using alkanolamines was patented in 1930. Several amine solvents are available as of the mid-1990s. The most widely used are monoethanolamine [141-43-5], diethanolamine [111-42-2], diglycolamine [929-06-6], and methyldiethanolamine [105-59-9]. Amine processes are generally applicable when hydrogen sulfide concentration in the feed gas is relatively low (eg,... 

Jeffery, P.-G., Kipping, P. J. The determination of carbon dioxide and nitrous oxide in solutions of monoethanolamine. Analyst 87, 594 (1962). 

Huang Q, Li Y, Jin X et al (2011) Chloride ion enhanced thermal stability of carbon dioxide captured by monoethanolamine in hydroxyl imidazolium based ionic liquids. Energy Environ Sci 4(6) 2125-2133... 

Some shift converters have high- and low-temperature sections, the high-temperature section converting most of the carbon monoxide to carbon dioxide. Cooling to 38°C is followed by carbon dioxide absorption with monoethanolamine (HOCH2CH2NH2). The carbon dioxide (an important by-product) is desorbed by heating the monoethanolamine and reversing this reaction. 

Alternatively, hot carbonate solutions can replace the monoethanolamine. A methanator converts the last traces of carbon dioxide to methane, a less interfering contaminant in hydrogen used for ammonia manufacture. 

Monoethanolamine is the oldest and probably still the most widely used solvent (Fig. 1). For desulfurization of natural gas, a 10 to 30% aqueous solution of monoethanolamine is normally used and a variety of solvents are available that vary in solvent selectivity for absorption of hydrogen sulfide and carbon dioxide, and this property, as well as the composition of the impurities in the gas being treated, frequently determines the choice of solvent. Some of... 

H. Hikita, S. Asai, H. Ishikawa, et ah, The kinetics of reactions of carbon dioxide with monoethanolamine, diethanolamine and triethanolamine by a rapid mixing method, Chem. Eng. Journal, 1977, 13, 7-12. 

In this case, carbon dioxide reacts reversibly in the adsorber with aqueous alkaline solutions to form a carbonate adduct (configuration 1). This adduct decomposes in the stripper upon heating. In early ammonia plants, an aqueous solution of 15-20 wt % monoethanolamine (MEA) was always standard for removing CO2. Primary alkanolamine solutions, however, require a relatively high heat of regeneration so that, nowadays, secondary and tertiary ethanol amines are mainly used. 

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