Ethane absorption

Ethylenediamine.—The volume of this compound is rapidly increased by the action of the silent electric discharge. Hydrogen is primarily developed, with some ammonia, nitrogen, and methane or ethane. Absorption of nitrogen and ammonia soon occurs, and hydrogen is split off. In the second stage the formation of condensation products (polyamines) presumably predominates, while in the first period the decomposition of the material started with prevails. 

The butane-containing streams in petroleum refineries come from a variety of different process units consequently, varying amounts of butanes in mixtures containing other light alkanes and alkenes are obtained. The most common recovery techniques for these streams are lean oil absorption and fractionation. A typical scheme involves feeding the light hydrocarbon stream to an absorber-stripper where methane is separated from the other hydrocarbons. The heavier fraction is then debutanized, depropanized, and de-ethanized by distillation to produce C, C, and C2 streams, respectively. Most often the stream contains butylenes and other unsaturates which must be removed by additional separation techniques if pure butanes are desired. 

LPG is recovered from natural gas principally by one of four extraction methods turboexpander, absorption (qv), compression, and adsorption (qv). Selection of the process is dependent on the gas composition and the degree of recovery of ethane and LPG, particularly from large volumes of lean natural gas. 

Adsorption. Adsorption processes have been used to recover hydrocarbons that are heavier than ethane from natural gas. Although the adsorption process has appHcations for the recovery of pentane and heavier hydrocarbons from lean gas, the percentage recovery of LPG components in these plants usually is low compared to the normal recovery of LPG in modem turboexpander or oil-absorption plants. 

When acetylene is recovered, absorption—desorption towers are used. In the first tower, acetylene is absorbed in acetone, dimethylformarnide, or methylpyroUidinone (66,67). In the second tower, absorbed ethylene and ethane are rejected. In the third tower, acetylene is desorbed. Since acetylene decomposition can result at certain conditions of temperature, pressure, and composition, for safety reasons, the design of this unit is critical. The handling of pure acetylene streams requires specific design considerations such as the use of flame arrestors. 

Absorption recovers valuable light components such as propane/propylene and butane/ butylene as vapors from fractionating columns. These vapors are bubbled through an absorption fluid, such as kerosene or heavy naphtha, in a fractionating-like column to dissolve in the oil while gases, such as hydrogen, methane, ethane, and ethylene, pass through. Absorption is effectively performed at 100 to 150 psi with absorber heated and distilled. The gas fraction is condensed as liquefied petroleum gas (LPG). The liquid fraction is reused in the absorption tower. 

Figure 13.14 The origin of spin-spin splitting in bromo-ethane. The nuclear spins of neighboring protons, indicated by horizontal arrows, align either with or against the applied field, causing the splitting of absorptions into multiplets.

From the gaseous product, HCl is recovered by absorption in water. The other gases (CO, propane, ethane) are incinerated and released. The liquid phase is separated into an organic condensate and an aqueous condensate. Solutions containing HCl can be reused in the downstream separation process. The solid phase... 

In a sensitive and specific colorimetric method 1,1,1-trichloro-2,2-bis(p-methoxyphenyl)-ethane is extracted from plant or animal tissue, using benzene or petroleum ether as the solvent. The solvent is evaporated at room temperature by a current of air and the residue dehydroha log ena ted with 2% alcoholic potassium hydroxide. By petroleum ether extraction the resulting 1,1-dichloro-2,2-bis(p-methoxyphenyl)-ethylene is removed from the reaction mixture. After the solvent is removed by air evaporation the dehydroha log ena ted methoxychlor is isolated from the nonsaponifiable portion of the fats and waxes by dissolving the residue in hot acetone, chilling, and filtering. After the acetone is removed by air evaporation, the residue is treated with 85% sulfuric acid. This produces a red solution with an absorption maximum at 555 m/z, the intensity of which can be read on a colorimeter and is a function of the methoxychlor concentration. Beer s law is obeyed over the range of 1 to 50 micrograms. 

The foregoing equation can be used to give the evolution of (E). For N2, exponential decay of (E) was seen, indicating efficient thermalization but this was not observed for He. For highly efficient moderators such as ethane, the absorption signal essentially follows the pulse shape. 

The initial product of the inhibition step is not known in this case and may be a molecular complex.8 The direct reaction of the ethane with the peroxy radical is an example of a covalent compound giving a reaction resembling that of a related free radical. The molecular weight determination by Gomberg was therefore a necessary part of the proof that he was dealing with radicals and not merely an unusually reactive hydrocarbon. The presence of free radicals has since been confirmed by measurements of the paramagnetic susceptibility and the paramagnetic resonance absorption.9-10 The latter evidence also rules out an alter-... 

In the cyclophane 1, although the overlap between the n-system (2p) and the bridging cr-bonds (2s2p) is most effective, these orbital energy levels match worst, the first ionization potentials being 9.25 eV for benzene and 12.1 eV for ethane. As a result, the HOMOs are the almost pure it MOs with the b2g and b3g combinations. Both the PE spectrum and theoretical calculation demonstrate the degeneracy of the two HOMO levels. The absorption bands are attributed to the 17-17 transitions associated with the HOMOs. 

Figure 4 illustrates the infrared spectrum for a sample of PPE. The absorptions of the peaks at 3.4, 6.9 and 7.3 pm were assigned to C-H stretch and C-H bending frequencies in CH2 and CH3 (33). These absorptions are proportional to the surface density of deposited ethane (16). However, the absorptions at photons near 10 pm are attributable to OH deformations and CO stretchings of alcoholic groups and vibrations of alkyl ketones (22). They also indicate the existence of branches in unsaturated chain (33). 

Hubrich C, Stuhl F. 1980. The ultraviolet absorption of some halogenated methanes and ethanes of atmospheric interest. J Photochem 12 93-107. 

The complex Os04(4-dimethylaminopyridine) has been synthesized. It shows an absorption at 473 nm which is assigned to LMCT transition. Excitation of this band in ethanol leads to a reduction of Os to Os and oxidation of ethanol to ethanal with a quantum yield of 0.1 at 436 nm. 

Figures 4.44 and 4.45 show absorption spectra of some simple chlorofluoro-methanes and ethanes, respectively (Hubrich and Stuhl, 1980). Tables 4.37 and 4.38 give the recommended absorption cross sections for some of these compounds (DeMore et al., 1997). None of these compounds absorb in the actinic region above 290 nm, but do around 180-200 nm, wavelengths only found in the stratosphere. As discussed in Chapter 12, it is photolysis at these short wavelengths to generate atomic chlorine that is responsible, along with bromine and perhaps in some cases, iodine atoms, for the chain destruction of stratospheric ozone.

Hubrich, C., and F. Stuhl, The Ultraviolet Absorption of Some Halogenated Methanes and Ethanes of Atmospheric Interest, J. Photochem., 12, 93-107 (1980). 

On the other hand, for strontium di(9-fluorenyl)ethane (n 2) the tight ion pair spectrum ( 361 nm for this salt) remains practically unchanged down to -90°. When this temperature is reached, a small fraction (W0.05) of loose ion pairs ( 391 nm) can be detected In the optical spectrum. On further cooling, the 391 nm peak gradually increases with time, and when kept at about -100°C the only absorption maximum In the spectrum after one hour Is that of the 391 nm loose Ion pair. Following this conversion (an Isosbestic point is observed), precipitation... 

---