NH3 absorptions

It should be noted that the highest possible absorption rates will occur under conditions in which the hquid-phase resistance is negligible and the equilibrium back pressure of the gas over the solvent is zero. Such situations would exist, for instance, for NH3 absorption into an acid solution, for SO9 absorption into an alkali solution, for vaporization of water into air, and for H9S absorption from a dilute-gas stream into a strong alkali solution, provided there is a large excess of reagent in solution to consume all the dissolved gas. This is known as the gas-phase mass-transfer limited condition, wrien both the hquid-phase resistance and the back pressure of the gas equal zero. Even when the reaction is sufficiently reversible to allow a small back pres-... 

In the first freeze drying plant [2.9] phosphorous pentoxide has been used to absorb the water vapor, but to day this technique is outdated. The development of refrigeration technology with compressors or NH3 absorption and the availability of LN2 has replaced water absorption by silica gel or similar products. Some trials aiming to revive this technology are detailed in Section 1.2.6. 

According to Strobel (945,946) the upper atmosphere ( > 100 km) photochemistry is dominated by the photolysis of methane. Only below 100 km the atmosphere contains suflicient ammonia to be photochemically important. The photochemically effective wavelengths for NH3 photolysis are in the range from 1600 A, the onset of CH4 absorption, to 2300 A, the onset of NH3 absorption. The photolysis of NH3 has already been discussed (see... 

Heats of NH3 absorption further confirm that the heteropolyacids are stronger acids than zeolites or simple metal oxides 150kJmol 1 for HZSM-5 and 140 kJ mol" for y-Al203 (133). 

Fig. 17. Differential heat of NH3 absorption as a function of the ammonia uptake for heteropolyacids. (From Ref. 132.)...

FIGURE 2 Solubility data for NH3 absorption from air using H20. [Data from Perry, R. H., ed. (1985). Chemical Engineer s Handbook, McGraw-Hill, New York.]... 

In the next paper of the series, Takeyama and Miyama reported the kinetics of NH3 disappearance following the induction period, studied by monitoring NH3 absorption. This required determining the extinction coefficient of NH3 at 2245 A at various temperatures. Over the temperature range of 2100 -2600 °K, they found the NH3 consumption to obey the rate law... 

A further advantage of absorption plus reaction is the increase in the mass-transfer coefficient. Some of this increase comes from a greater effective interfacial area, since absorption can now take place in the nearly stagnant regions (static holdup) as well as in the dynamic liquid holdup. For NHj absorption in H2SO4 solutions, K a was 1.5 to 2 times the value for absorption in water.Since the gas-film resistance is controlling, this effect must be due mainly to an increase in effective area. The values of K a for NH3 absorption in acid solutions were about the same as those for vaporization of water, where all the interfacial area is also expected to be effective. The factors and... 

During absorption, a gas component is selectively dissolved by contact with a liquid in which the component is soluble. Absorption is used for scrubbing gas streams to remove components such as CO2, H2S, SO2 and NH3. Absorption may be either physical or chemical (or a combination of both). Physical absorption involves the solubility (Henry coefficient). Chemical absorption involves a reaction of the primarily physically absorbed solute with the absorbing... 

If Henry s law constant for NH3 absorption is described via and water concentration is... 

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