Aniline adsorption

Figure 25. Various anilines adsorption on Cu0.5Zn0.5Fe204 at 100°C.

The cumene cracking activities over zeolites with different amounts of pyridine, quinoline and aniline adsorption were studied. The reaction rate data of cumene cracking were treated by linearization of eq. (11) as follows ... 

Huang SX, Fischer DA, Gland JL (1996) Aniline adsorption, hydrogenation, and hydrogenolysis on the Ni(100) surface. J Phys Chem 100 10223-10234... 

Ward and Upchurch (340) found an inverse relationship between the solubilities of 18 substituted anilines and their adsorption by nylon (R2 = 0.77) and cellulose triacetate (R = 0.80). It was suggested that steric and electronic effects of the molecules were also responsible for the adsorption differences of the compounds. Because of the low solubilities of the substituted anilines, adsorption by organic matter probably occurs at lipophilic sites through dipole-dipole interactions—e.g., hydrogen bonding or charge-transfer complexes. Low adsorption at clay surfaces probably occurs because the hydrophobic molecules do not readily associate with hydrated surfaces. Adsorption of the substituted anilines by dry clays might occur on the soil surface for instance, but in the... 

In the first case, to calculate adsorption, the values of the equilibrium surfactant concentrations in any phase may be taken, since under equilibrium conditions the chemical potentials of all components in the water and organic phases are equal and are interrelated through the distribution constant [44, 51]. Investigating aniline adsorption in the water-toluene system, Rehbinder was the first to experimentally show that at equilibrium the adsorption may be calculated from any phase [52]. He also proved the validity of the following equality ... 

Al-Johani H, Salam MA (2011) Kinetics and thermodynamic study of aniline adsorption by multi-waUed carbon nanotubes from aqueous solution. J Colloid Interface Sci 360 760-767. doi 10.1016/j.jcis.2011.04.097... 

The adsorption equation shows that a solute may very strongly lower the surface tension of a solvent, but cannot strongly raise it, since although T may reach high values by positive adsorption (in some cases, as with solutions of some aniline dyes, the pure solute appears as a thin skin on the surface), it can never sink below that of the pure solvent by negative adsorption. 

The adsorption pseudo-capacitance, Cg, is dominated by the factor ddjdE and hence a plot of C9 versus E gives direct information about the coverage. Figure 4 shows a Cg-E plot for aniline at mercury in aqueous solu-... 

A marginal hydrogenation of the benzenic ring of 1-naphthylamine leading to 5,6,7,8-tetrahydro-l-naphthylamine [72] was explained as due to a weaker adsorption of the benzene part than of the aniline part of the naphthylamine. However, this reaction was disregarded for the HDN of 1-naphthylamine, as the minor role it could play under the studied conditions. 

Aromatic molecules can be polymerized catalytically on clean metal surfaces, or electrochemically to produce oriented polymer films. Initial adsorption of aromatic molecules occurs by electron donation from the aromatic molecule to the surface. This electron donation creates radical cations that can polymerize. Molecular orientation in the films depends on the stable bonding configuration of the radical cation. Thiophene, pyridines, and pyrrole all polymerize with the ring substantially perpendicular to the surface, whereas aniline polymerizes with the phenyl rings parallel to the surface. The catalytically... 

A combination of column adsorption chromatography on basic alumina and GC of the eluate served for characterization of the trace fraction of nitrogen-containing compounds in hydroprocessed naphtha. These were subdivided into groups of four types, namely pyridines, pyrroles (the most abundant), anilines and indoles125. 

A comparison of active (using pumps) and passive (relying on diffusion) sampling techniques for the determination of nitrobenzene, benzene and aniline in air was mentioned in Section IV.A77. Several LLE methods for nitroaromatic compounds dissolved in water were evaluated. High recoveries were achieved with discontinuous or continuous extraction with dichloromethane, adsorption on a 1 1 1 mixture of Amberlite XAD-2, -4 and -8 resins and elution with dichloromethane445. 

As far as the mechanism of DMC-mediated mono-A-methylation reactions is concerned, adsorption phenomena of reagents over zeolite catalysts have to be examined. Model cases of aniline and DMC are suitable to this investigation. 

Based on Figure 4.6 and Scheme 4.12, the proposed mechanism for the mono-A-methyl of aniline with DMC is described pictorially on Scheme 4.13. Once the reagents (amine and DMC) diffuse into the supercages of NaY, they can approach each other only according to the steric requisites of their adsorption... 

O Brien, J., Curtin, T., and O Dwyer, T.F. (2005) An investigation into the adsorption of aniline from aqueous solution using H-beta zeolites and copper-exchanged beta xeolites. Adsorpt. Sd. Technol, 23, 255. 

Weber et al. (2001) reported that initial sorption of aniline (<4 h) increases with decreasing pH. The long term adsorption rate (>4 h) is almost independent of solution pH greater than the pKa... 

A detailed investigation of aniline N-methylation on Cui xZnxFc204 was carried out through in situ FTIR spectroscopy. The reactants (aniline and methanol) and possible products (NMA, DMA and o-toluidine) were adsorbed on the catalysts and analyzed [106,107]. Adsorption of methanol indicated a dissociative chemisorption as methoxy species on catalyst surface at 100°C. As the temperature increased, oxidation of methoxy species to formaldehyde to dioxymethylene to formate species was observed, and above 300°C complete oxidation takes place to CO, CO2 and H2. Indeed methanol alone on Cui xZnxFc204 and Cui.xCoxFc204 behaves in a similar way [79,107]. 

Adsorption of aniline on Cui xZnxFc204 at <100°C indicates a simple molecular adsorption through N-atom on an acid-base pair site. However, above 100°C, N-H bond dissociates and aniline chemisorbed strongly on the catalyst surface. Chemisorbed aniline... 

A summary of aniline N-methylation mechanistic features on Cui xZnxFe204 ferrospinel catalysts is given in Figure 27. It was possible, due to in-situ IR studies, to observe a dissociative adsorption and possible orientation of reactants on the catalyst surface, their conversion to product at low temperatures, and desorption-limited kinetics, all under conditions that are close to the reaction conditions. Although Cu is the active center for the aniline A-methylation reaction, and IR studies reveal that Zn acts as the main methyl species source. 

---