Amine absorption systems

We have proposed an initiation mechanism for the ROOH-amine system in which some H-bond complex may be formed [36]. Then Sun et al. [37,38] thoroughly investigated the initiation mechanism of ROOH-Amine through IR spectra of TBH-triethylamine, TBH-DMT, and CHP-DMT. From the wideness of the shift of OH absorption bands at 3120, 3336, and 3257 cm were... 

McCann N, Maeder M, Attalla M (2008) Simulation of enthalpy and capacity of C02 absorption by aqueous amine systems. Ind Eng Chem Res 47(6) 2002-2009... 

The cooled process gas that leaves the Syngas Scrubber is fed to the Amine unit. The amine unit consists of an absorption-stripping system plus associated equipment. In this system a circulating amine stream (activated MDEA - or Methyl Diethanolamine) absorbs the C02 in the C02 Absorber. The amine is regenerated in the C02 Stripper with the C02 being recycled to the compressor. 

In an amine system, one way to increase absorption is to increase amine concentration. A higher amine concentration requires 1) more extensive filtration to keep the solution clean and 2) the addition of corrosion inhibitors and to minimize corrosion. Another option is to change from monoethanolamine (MEA) to methyl diethanolamine (MDEA)86. 

Table 3. Absorption maxima of azophenol crown 4-sec. amine systems in EtOH (nm)...

Fig. 12. Absorption maxima (in nm) of visible spectra for dye-amine systems in CHC13...

Fig. 18. Absorbance at absorption maxima of podand dye-amine systems in chloroform...

An azophenol crown including a pyridine unit, 66, (Fig. 19) reacts with all of amines in acetonitrile to form ammonium phenolates. The absorption maxima of 66-prim, amine systems appear in a region of 574-586 nm, which is definitely distinct from those of sec. and tert. amine systems (Xmax 602 — 606 nm except for the dimethylamine system which gave 592 nm) as shown in Fig. 19. On the other hand, a dyed crown including an additional benzene unit, 65 (Fig. 19), reacts with various amines to make ammonium phenolates which show absorption maxima of nearly constant wavelength. 

T vo carbon-capture processes have been studied in this chapter. Both use a two-column absorber/stripper flowsheet. The low-pressure amine system presents more problems in dynamic simulation than does the high-pressure physical absorption system. The plantwide control structures that are effective for the two systems are quite sunilar. 

NIR (near infrared) Epoxy/amine systems [72] Homogeneous (bulkand solution) and heterogeneous (suspension and emulsion) polymerizations [73-75] Non-invasive/Broad bands, chemometry required and of limited usefulness for waterborne systems because of the strong absorption of water All polymerization techniques... 

The compounds 1 (Xmax = 411 nm, s = 1,460 dm mol ) and 2 ( max = 418 nm, e = 5,470 dm mol" ) show an even stronger absorption at their maximum than CQ (Figure 4.6) [MOS 08]. However, the absorption spectra of acyl germanium initiators only slightly overlap with emission spectra of common dental polymerization lamps. In this sense, the efficiency of 1 is rather limited compared to CQ/amine systems [GAN 08]. Also, it has been shown that increasing concentrations of these t) es of initiators decreases the depth of cure compared to CQ-/amine-based restorative materials [MOS 08, MOS 07]. 

This concludes the major units in a refinery. There is one major auxiliary unit in a refinery that requires cleaning. This is the amine unit While there are many processes to remove HjS and/or CO2 from gas streams, the most widely used are the amine systems that depend on the reactivity of H2S with amino nitrogen for their absorption properties. The most currently used processes today are monoethanolamine (MEA), diethanolamine (DEA), diglycolamine (DGA), and diisopropylamine (DIPA). Deposits/solvent related to units described above that are not to be considered in more detail are given in Table 1. 

When H2S is the solute to be removed from the gas stream, the design of an amine system is similar to that just described for CO2 absorption. However, the K a value for CO2 absorption into MEA is only about 40% of the Koa value for H2S absorption into the same MEA solution. The Koa value for H2S absorption is influenced by the same variables in the same manner as for CO2 absorption, with the exception of the temperature influence. The Kq3. for H2S absorption decreases with increasing solvent temperature, probably because of reduced H2S solubility in the liquid phase. The Kca value applicable at 75" F will be reduced to at higher liquid temperatures. 

Procedures, General Design Concept, Choice of Solvent, Selection of Column Diameter, Physical Absorption, Solvent Absorption, Natural Gas Dehydration, Gas Drying, Sulfuric Acid Manufacture, Formaldehyde Absorption, Absorption with Chemical Reaction, Cracked Gas Scrubbing, Amine Systems, Hot Carbonate Systems, Multicomponent Absorption, Reboiled Absorbers, Example Problem, Notation, References... 

TABLE 3-1 Emittance (e) and Solar Absorptance (a s) values calculated for a Poly-(aromatic Amine) system with a polymeric dopant in several device configurations (here labeled CONI, CON2, and CONS), from difriise reflectance data, as a function of applied potential in 2-electrode mode. Data courtesy of Ashwin -Ushas Corp., Inc. 

A simplified flow diagram of an amine system appears in Fig. 6.43. Feed gas is passed counterflow to the liquid in a tray or packed tower. The absorption process is a chemical reaction between the acid gases, water, and amine in which amine carbonates, bicarbonates, and hydrosulfides are formed. The rich amine solution is stripped of the acid gases in a distillation column by the addition of heat, which reverses the chemical reaction. 

Thioxanthones (Table 11) in conjunction with tertiary amines are efficient photoinitiators [140] with absorption characteristics that compare favorably with benzophenones absorption maxima are in the range between 380 and 420 nm (e = lO L moP cm ), depending on the substitution pattern. The reaction mechanism has been extensively investigated by spectroscopic and laser flash photolysis techniques [64,141-143]. It was found that in conjunction with tertiary amines, reactions similar to that of benzophenone-amine systems take place. 

I. Alatiqi, M.F. Sabri, W. Bouhamra, E. Alper, Steady-state rate-based modelling for C02/amine absorption-desorption systems. Gas Sep. Purif. 8 (1994) 3-11. 

A second type of uv curing chemistry is used, employing cationic curing as opposed to free-radical polymerization. This technology uses vinyl ethers and epoxy resins for the oligomers, reactive resins, and monomers. The initiators form Lewis acids upon absorption of the uv energy and the acid causes cationic polymerization. Although this chemistry has improved adhesion and flexibility and offers lower viscosity compared to the typical acrylate system, the cationic chemistry is very sensitive to humidity conditions and amine contamination. Both chemistries are used commercially. 

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