Solvents monoethanolamine

The most widely used amine is monoethanolamine (MEA), which is considered as a benchmark solvent because of its high cyclic capacity, significant absorption-stripping kinetic rates at low C02 concentration and high solubility in water. Some other amine-based solvents such as diethanolamine (DEA), triethanolamine (TEA), diglycolamine (DGA), N-methyldiethanol-amine (MDEA), piperazine (PZ), 2-amino-2-methyl-l-propanol (AMP) and N-(2-aminoeth-yl)piperazine (AEP) have also traditionally been utilised. 

The H2 is separated from C02 and purified at the final stage of the process. Older variations of the SMR process (Figure 2.5a) used solvents to remove the acid gas (C02) from the gaseous stream after WGS reactors. Solvents commercially used for C02 removal in the gas separation unit include monoethanolamine (most preferred and widely used solvent), water, ammonia solutions, potassium carbonate solutions, and methanol. This operation allows the reduction of C02 concentration in the process gas to about 100 ppm. The remaining... 

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,... 

Solvents used for hydrogen sulfide absorption include aqueous solutions of ethanolamine (monoethanolamine, MEA), diethanolamine (DEA), and diisopropanolamine (DIPA) among others ... 

Mixed ligand complexes of Zn2+ with en and monoethanolamine (mea) in H20-MeOH systems have been investigated.192 At <20% MeOH, the presence of the complexes [Zn(en) —(mea)3 ]2+ (n = 0-3) and the complexes [Zn(en)2]2+ and [Zn(mea)2]2+ is indicated. At >20% MeOH, only the tris complexes (n = 0 or 3) are found. Stability constants for mixed complexes of Zn2+ with en and glycine in mixed aqueous solutions of methanol, dioxane, acetonitrile and DMF have been determined.193 In general, the stability constants increase with increasing composition of the co-solvent in the order H20 < MeOH < MeCN < DMF < dioxane. 

Typically, a solvent that is chemically similar to the target solute or that reacts with it will provide high solubility. Water is often used for polar and acidic solutes (e.g., HCl), oils for light hydrocarbons, and special chemical solvents for acid gases such as C02, S02, and H2S. Solvents are classified as physical and chemical. A chemical solvent forms complexes or chemical compounds with the solute, while physical solvents have only weaker interactions with the solute. Physical and chemical solvents are compared and contrasted by examining the solubility of C02 in propylene carbonate (representative physical solvent) and aqueous monoethanolamine (MEA representative chemical solvent). 

Since that time, a general correlation between yield of extract and carbon content has been reported for ethylenediamine (Table 10.2). Various other amine solvents (e.g., monoethanolamine) show similar behavior insofar as the extract yield may decrease markedly with increase in rank for coals under 85% carbon. On the other hand, the yield of extract using solvents such as benzylamine, piperidine, and pyridine may show much less variation with rank, and the effectiveness of many solvents may decrease markedly for coal having more than 88% carbon (van Krevelen, 1965). 

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... 

Substantial improvements have been made in the energy efficiency of CO2 removal systems. The first large-scale ammonia plants in the 1960 s typically used monoethanolamine (MEA) as a solvent. Energy input was over 50,000 kcal/kg-mol of CO2 removed. In 2001 plants use improved solvents and designs that can reduce the energy input to about 10,000 kcal/kg-mol of CO2 removed57. 

Amine solvents are widely used for sour gas removal, in syngas, fertilizer and natural gas plants. They are mainly used to withdraw the sour components CO2 and H2S from process gas streams, and the process is usually carried out in packed-bed columns. Depending on the specifics of a particular process, either aqueous primary (e.g., monoethanolamine, MEA), secondary (e.g., diethanolamine, DEA), tertiary (e.g., methyldiethanolamine, MDEA) amines or aqueous amine blends are employed. 

Monoethanolamine is used primarily in pharmaceutical formulations for buffering purposes and in the preparation of emulsions. Other uses include as a solvent for fats and oils and as a stabilizing agent in an injectable dextrose solution of phenytoin sodium. 

To date, all commercial plants for separation and concentration of CO2 use chemical absorption with a monoethanolamine solvent. This solvent was developed over 60 years ago to remove acid gases, such as CO2 and H2S, from natural gas streams. Monoethanolamine absorption is popular for the existing markets for high-purity CO2, because it produces a very high-grade product. The process has also been used to remove CO2 from flue gases, but it had to be modified... 

At ambient temperature, carbon dioxide is three to five times more soluble in most organic solvents than in water (Table I). The differences among polar (e.g. methanol, = 0.139) and nonpolar (e.g. carbon tetrachloride, % = 0- 094) solvents are small. Two solvents which have recently been of practical interest in removing carbon dioxide from natural gas are propylene carbonate ( ) and monoethanolamine (10) - this last ought to be classified as an acid-base reaction. Judging from the number of entries in the 10th collective index to Chemical Abstracts, there is a substantial chemical engineering literature on this topic. 

The joint evaluation report gives the results of toxicity testing on the final bitumen-salt products from the destruction of GB and GD. The toxicity was again measured in rats, with LD50 results of >5 x 103 mg/kg. This is a low level of toxicity and puts the material in the Russian State category Level III, which makes it as toxic as the monoethanolamine solvent. 

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