Amines vapor pressure

The amine cooler is typically an air-cooled, fin-fan cooler, which low-er.s the lean amine temperature before it enters the absorber. The lean amine entering the absorber should be approximately 10°F warmer than the sour gas entering the absorber. Lower amine temperatures may cause the gas to cool in the absorber and thus condense hydrocarbon liquids. Higher temperatures would increase the amine vapor pressure and thus increase amine losses to the gas. The duty for the cooler can be calculated from the lean-amine flow rate, the lean-amine temperature leaving the rich/lean exchanger and the sour-gas inlet temperature. 

The methylamiaes and ethylamiae have vapor pressures above atmospheric at ambient temperatures and are available ia the pure form only ia pressurized containers. These amines are also sold as aqueous solutions with vapor pressures below atmospheric for ease of handling. Diethylamiae, triethylamiae, and all of the higher mol wt amines are sold as the pure compounds. 

Alkylamiaes are toxic. Both the Hquids and vapors can cause severe irritations to mucous membranes, eyes, and skin. Protective butyl mbber gloves, aprons, chemical face shields, and self-contained breathing apparatus should be used by aH personnel handling alkylamiaes. Amines are flammable and the lower mol wt alkylamiaes with high vapor pressures at ordiaary temperatures have low flash poiats. Amines should be handled ia weH-veatilated areas only after eliminating potential sources of ignition. 

Catalysts serve a dual purpose in one-component moisture-curing urethanes. The first purpose is to accelerate the prepolymer synthesis. The second purpose is to catalyze the curing reaction of the adhesive with moisture. The most common catalysts used to promote both prepolymer formation (NCO/OH) and later the adhesive curing reaction (NCO/H2O) are dibutyltin dilaurate and DMDEE ((tertiary amine. A stabilizer such as 2,5-pentanedione is sometimes added when tin is used, but this specific stabilizer has fallen from favor in recent years, due to toxicity concerns. DMDEE is commonly used in many one-component moisture-curing urethanes. DMDEE is one of the few tertiary amines with a low alkalinity and a low vapor pressure. The latter... 

DGA systems typically circulate a solution of 50-70% DGA by weight in water. At these solution strengths and a loading of up to 0.3 mole of acid gas per mole of DGA, corrosion in DGA systems is slightly less than in MEA systems, and the advantages of a DGA system are that the low vapor pressure decreases amine losses, and the high solution strength decreases circulation rates and heat required. 

It can be seen that water has the highest vapor pressure therefore, provided these amines are stored in cool places with adequate ventilation, there is little risk of dangerous inhalation. Drums should not be stored in confined spaces. 

Recent developments for reactive C02 sorbents include sterically hindered amines such as 2-amino-2-methyl-l-propanol (AMP) and 1,8-p-methanediamine (MDA) and 2-piperidine ethanol (PE), which are claimed to have good reversible C02 capacity (Veawab et al., 1998) and low-temperature molten salts called ionic liquids (Bates et al., 2002). Ionic liquids are attractive due to their negligible vapor pressure up to their decomposition at... 

In the multimedia models used in this series of volumes, an air-water partition coefficient KAW or Henry s law constant (H) is required and is calculated from the ratio of the pure substance vapor pressure and aqueous solubility. This method is widely used for hydrophobic chemicals but is inappropriate for water-miscible chemicals for which no solubility can be measured. Examples are the lower alcohols, acids, amines and ketones. There are reported calculated or pseudo-solubilities that have been derived from QSPR correlations with molecular descriptors for alcohols, aldehydes and amines (by Leahy 1986 Kamlet et al. 1987, 1988 and Nirmalakhandan and Speece 1988a,b). The obvious option is to input the H or KAW directly. If the chemical s activity coefficient y in water is known, then H can be estimated as vwyP[>where vw is the molar volume of water and Pf is the liquid vapor pressure. Since H can be regarded as P[IC[, where Cjs is the solubility, it is apparent that (l/vwy) is a pseudo-solubility. Correlations and measurements of y are available in the physical-chemical literature. For example, if y is 5.0, the pseudo-solubility is 11100 mol/m3 since the molar volume of water vw is 18 x 10-6 m3/mol or 18 cm3/mol. Chemicals with y less than about 20 are usually miscible in water. If the liquid vapor pressure in this case is 1000 Pa, H will be 1000/11100 or 0.090 Pa m3/mol and KAW will be H/RT or 3.6 x 10 5 at 25°C. Alternatively, if H or KAW is known, C[ can be calculated. It is possible to apply existing models to hydrophilic chemicals if this pseudo-solubility is calculated from the activity coefficient or from a known H (i.e., Cjs, P[/H or P[ or KAW RT). This approach is used here. In the fugacity model illustrations all pseudo-solubilities are so designated and should not be regarded as real, experimentally accessible quantities. 

Alkad A process for improving the safety of alkylation processes using hydrofluoric acid as the catalyst. A proprietary additive curtails the emission of the acid aerosol that forms in the event of a leak. Based on observation of G. Olah in the early 1990s that liquid polyhydrogen fluoride complexes (of amines such as pyridine) depress the vapor pressure of HF above alkylation mixtures. Developed by UOP and Texaco and operated at Texaco s refinery at El Dorado, TX, since 1994. A competing process is ReVAP, developed by Phillips and Mobil. 

UOP in a joint venture with ChevronTexaco developed an additive technology named Alkad . The additive is based on HF salts of amines, which form liquid onium polyhydrogen fluoride complexes with HF, reducing the vapor pressure of the catalyst 65% to more than 80% aerosol reduction is claimed with this additive. As in the ReVap technology, additional separation columns have to be installed. Both additives are claimed to increase the product octane number, especially when propene, isobutylene, and pentenes are employed in the feedstock. 

In these equations RR NH is the chemical formular of the alkanolamine. Tertiary amines, such as triethanolamine, lack the extra hydrogen atom and do not form carbamates. The chemical reactions are accompanied by the vapor-liquid equilibria of the volatile species C02, H2S and H20. Under the conditions of interest, the vapor pressures of the amines are very small and it can be assumed that the amine is present only in the liquid phase. 

The power and beauty of jet techniques is the ability to produce a beam of molecules that are vibrationally and rotationally cold but are still vapors. These advantages of supersonic expansions, however, rely on the possibility of producing sufficient partial vapor pressure of the molecules of interest, typically a few millibars. By regulating the temperature of the beam, it is possible to vary the vapor pressure of the sample to the required values. As an example, hquid molecules, such as aromatic alcohols, have to be heated at about 80 °C to obtain the right vapor concentration in the beam, while other largely volatile molecules, such as aliphatic amines, must be kept in a cold bath around 0 °C to avoid saturation. 

Molecular weights of the products as measured with vapor pressure osmometry were in good agreement with the calculated ones. Interestingly, resins based on hexahydrophthalic anhydride and diisopropanolamine with tertiary amines as functional groups are soluble in water without quaternization of the... 

A vapor pressure of 4.5><10 mm Hg at 20 °C has been reported (DCMA 1989). Prior to OSHA 1974 regulations, benzidine and 3,3 -dichlorobenzidine were manufactured in open systems that permitted atmospheric releases of suspended particles at the work site (Shriner et al. 1978), but no historical data were located specifically for 3,3 -dichlorobenzidine emissions (atmospheric or in water). The absence of data may be attributed to analytical methods used at that time that could not distinguish benzidine from its derivatives or many other aromatic amines (Shriner et al. 1978). Under OSHA regulations adopted in 1974, only closed manufacturing systems are permitted, and atmospheric emissions are presumably reduced because of this regulation. 

Honomer Properties (Table I). The amide/acetal 1 (R=He or Et) and Its amine precursor are Ames negative. Compound 1 shows a very high LD50 and low skin or eye Irritation. A low vapor pressure, Its liquid form and Infinite miscibility with water and common solvents are additional pluses. 

MDI offers a number of advantages. First, it is somewhat safe to use based on its much lower vapor pressure and is available in convenient forms. It is produced by the reaction of an amine and phosgene. The result is a mixture of multi-ring isocyanates. The purest form is the two-ring isomer shown in Figure 2.2. The isomer is recovered by distillation. What is left behind is the so-called polymeric MDI that... 

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