Ammonia catalyst exchange reaction

The log—log plot of the adsorption isotherm, which can possibly be correlated to the pressure-dependency of the catalytic reaction rate, is very flat. The adsorption of ethylene on nickel increases only by 10% for an increase of the equilibrium pressure by a factor of 10, although the surface is still far from being covered by a monolayer. The work of Laidler et al. (3), who studied the ammonia-deuterium exchange reaction on a promoted iron catalyst by means of the microwave method, also throws doubt on the zero-order kinetics with respect to observations made by Farkas (4). 

Sulfonation of anthraquinone to form the 1-sulfonic acid is achieved at approximately 120°C with 20% oleum in the presence of mercury or a mercury salt as a catalyst [2], Without this catalyst, the reaction produces the 2-sulfonic acid. Exchange with aqueous ammonia (30%) at about 175°C under pressure converts the potassium salt of 1-sulfonic acid to 1-aminoanthraquinone in 70 to 80% yield. To avoid sulfite formation, the reaction is performed in the presence of an oxidant, such as m-nitrobenzosulfonic acid, which destroys sulfite. 

The main by-products are 1-chlorobutadiene, produced from the residual dichloro 2-butenes or formed during the reaction, polymers, sodium chloride and monochloro-butenes (l-chloro 1-butene, 2-diloro 2-butenes, 2-chloro 1-butene, etc.) To control the undesirable polymerizations, the reaction takes place in an oxygen-free environment, at the lowest possible temperature, and with an inhibitor. Also effective is the presence of a solvent (methanol, ethanol) or a catalyst In this case, however, it is necessary to raise the caustic soda concentrations (30 per cent) or to employ other bases (liquid ammonia, ion exchange resins, etc.). In the absence of catalyst, the residence time is 3 to 5 h. and selectivity exceeds 95 molar percent for a once-through conversion of nearly 95 per cent... 

An objection to this view was made by Laidler (3), who found that the rate of the exchange reaction between deuterium and ammonia on a promoted iron catalyst passed through a maximum with increase of the ammonia pressure, contrary to the zero-order kinetics with respect to ammonia reported by Farkas (4). 

To cause the deuterium exchange reaction between hydrogen and ammonia to take place at a useful rate, it is necessary to have 1 to 2 m/o (mole percent) of potassium amide, KNH2, dissolved in the liquid phase to serve as a homogenous catalyst [C2]. Presence of potassium amide complicates the process for three reasons ... 

Polarographic evidence has been presented for the four-membered electron-transfer series [M(Et2dtc)2(mnt)F, z = -2-> 4-1, for the bis-(NA-disubstituted-dithiocarbamatodithiolene) complexes of iron and ruthenium. In the case of the latter metal all steps are reversible. For the exchange z = -1 to z = 0 for iron, there is a decrease in electron density around the metal and there may be significant Fe character in this species in which all six primary co-ordination sites are occupied by sulphur. Studies of the iron(ii)/(iii) couple in liquid ammonia show the reaction to be almost completely reversible on vitreous carbon or reduced gold electrodes. The process is interpreted in terms of the spin states of the metal centres. Iron(ra) carboxylate complexes have been postulated as catalysts in the reduction of iron(m) by phosphine in the presence of iodide in carboxylate media. ... 

The effectiveness of the promoter in the nitrogen exchange reaction can be further extended by supporting ruthenium/potassium on basic oxides such as BeO, CaO, and MgO in place of the more usual acidic and neutral oxides. A steady increase in the nitrogen exchange TON with support basicity is seen but, surprisingly, there is no effect on the ammonia synthesis TON relative to that observed on the carbon-supported catalysts. This may reflect a marked shift in the overall synthesis kinetics, which are strongly dependent on both the support and the promoter. 

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