Ammonia excess

Conversion at Equilibrium. The maximum urea conversion at equilibrium attainable at 185°C is ca 53% at infinite heating time. The conversion at equiUbtium can be increased either by raising the reactor temperature or by dehydrating ammonium carbamate in the presence of excess ammonia. Excess ammonia shifts the reaction to the right side of the overall equation ... 

The process flowsheet inside the battery limits (IBL) is at this stage unknown. However, the recycle of reactant may be examined. The patent reveals that the catalyst ensures very fast reaction rate. Conversion above 98% may be achieved in a fluid-bed reactor for residence time of seconds. Thus, recycling propylene is not economical. The same conclusion results for ammonia. The small ammonia excess used is to be neutralized with sulfuric acid (30% solution) giving ammonium sulfate. Oxygen supplied as air is consumed in the main reaction, as well as in the other undesired combustion reactions. 

The desired primary aminoalkylsilanes can be synthesized starting from the corresponding chloroalkyl precursors. The educts are reacted with excess ammonia (molar ratios 1 20 to 1 150) at pressures ranging from 30 to 200 bar and temperatures of 40 to 200 °C. The large ammonia excess is necessary to supress side reactions yielding higher alkylated amines (Eq. 1). 

If PbCl4 is allowed to react with liquid ammonia, one obtain black PbNCl or PbsN6Cl4 depending upon the reaction time and ammonia excess. Both arc explosive, the latter extremely so [208], PbCl and N, are the products of these... 

The NO reduction with ammonia in tlie presence of oxygen was performed over CeNa-MOR(58) at three NH3 to NO feed ratios, i.e., NH3/NO = 1, 1.3 or 1.6. As shown in Table 2, tlie maximum NO conversion (87 %) observed at equivalent amounts of NH3 and NO was found to improve to a complete conversion using a 30 % excess of ammonia at 300 - 500 °C. Moreover, tliere was no ammonia observed in the product gas at tins excess ratio above 200 °C. In otlier words, there was no ammonia slip even at a 30 % ammonia excess condition above 200 °C. At the NH3/NO ratio of 1.6, NO conversion remained at 100 %, though NH3 conversion was not complete under these conditions. It should be noted tliat at the NH3/NO ratio of 1.6, the converted ammonia (0.63 x572 ppm) at 200 °C is calculated to be 1.26 times more than tlie converted NO amount (0.81 x 357 ppm), and 1.33 times more at 300 °C (Table 2). These results suggest tliat under tlie present reaction conditions, ammonia can be introduced in excess of up to 30 % to obtain complete NO conversion witliout an ammonia slip above 200 °C. 

In conclusion, the observed complete conversions of NH3 and NO under excess ammonia conditions (> 200 °C) indicates great potential of cerium zeoUte. With ammonia applied in excess over NO, a stoichiometric amoimt of NH3 converts NO completely, and the excess NH3 will be simply converted to N2 by oxygen. With a certain shortage of NH3, a shghtly lower NO conversion may be obtained, but ammonia will be exhausted in the NO reduction anyway. This flexibility in ammonia feed concentration makes an approximate reductant injection control appUcable in practice. Under the present reaction conditions, an excess of ammonia up to 30 % is maximally allowed without ammonia slip. However, the effects of the reaction conditions, e.g., the space velocity, the presence of water or SO2, should be further examined to estimate such a "maximum ammonia excess value" in practice. 

The reactor is lowered into an electric furnace with its top near ground level, a seal is made at the top, and calcination begun. Ammonia, excess ammonium nitrate and water are removed as the temperature rises to... 

Operation with an excess of ammonia in the reactor has the effect of increasing the rate due to the term. However, operation with excess... 

An excess of ammonia in the reactor decreases the concentrations of monoetha-nolamine, diethanolamine, and ethylene oxide and decreases the rates of reaction for both secondary reactions. 

Thus an excess of ammonia in the reactor has a marginal eflFect on the primary reaction but significantly decreases the rate of the secondary reactions. Using excess ammonia also can be thought of as operating the reactor with a low conversion with respect to ammonia. 

The use of an excess of ammonia is home out in practice. A mole ratio of ammonia to ethylene oxide of 10 1 3delds 75 percent monoethanolamine, 21 percent diethanolamine, and 4 percent triethanolamine. Using equimolar proportions under the same reaction conditions, the respective proportions become 12, 23, and 65 percent. 

CH rCHCH NHCSNH. Colourless crystalline solid with a faint garlic-like odour m.p. 74 C. Manufactured by treating propenyl isothiocyanate with a solution of ammonia in alcohol. It has been given by injection in the treatment of conditions associated with the formation of excessive fibrous tissue. Toxic side reactions may occur. Propenyl thiourea is a chemical sensitizer for photographic silver halide emulsions. 

Because of ammine formation, when ammonia solution is added slowly to a metal ion in solution, the hydroxide may first be precipitated and then redissolve when excess ammonia solution is added this is due to the formation of a complex ammine ion, for example with copper(II) and nickel(II) salts in aqueous solution. 

If ammonia is used in large excess and the chlorine diluted with nitrogen, chloramine, NH Cl, is formed ... 

Ammonia may be estimated by dissolving the gas in a known volume of standard acid and then back-titrating the excess acid. In a method widely used for the determination of basic nitrogen in organic substances (the Kjeldahl method), the nitrogenous material is converted into ammonium sulphate by heating with concentrated sulphuric acid. The ammonia is then driven off by the action of alkali and absorbed in standard acid. 

By the evolution of ammonia with Devarda s alloy in alkaline solution in absence of ammonium ions this is used quantitatively, the ammonia being absorbed in excess standard acid and the excess acid back-titrated. 

Nitrogen trifluoride and trichloride can both be prepared as pure substances by the action of excess halogen on ammonia, a copper catalyst being necessary for the formation of nitrogen trifluoride. 

The reactions of aqueous solutions of nickel(II) salts with hydroxide ions, with excess ammonia, with sulphide ion and with dimethyl-glyoxime (see above) all provide useful tests for nickel(II) ions. 

It is readily dehydrated on warming, to give the black oxide CuO. It dissolves in excess of concentrated alkali to form blue hydroxo-cuprate(II) ions, of variable composition it is therefore slightly amphoteric. If aqueous ammonia is used to precipitate the hydroxide, the latter dissolves in excess ammonia to give the deep blue ammino complexes, for example [Cu(NH3)4(H20)2] ... 

When a copper(II) salt dissolves in water, the complex aquo-ion [Cu(H2p)6P is formed this has a distorted octahedral (tetragonal) structure, with four near water molecules in a square plane around the copper and two far water molecules, one above and one below this plane. Addition of excess ammonia replaces only the four planar water molecules, to give the deep blue complex [Cu(NH3)4(H20)2] (often written as [Cu(NHj)4] for simplicity). TTo obtain [Cu(NH3)6], water must be absent, and an anhydrous copper(II) salt must be treated with liquid ammonia. 

The aquo-complex [ZnlHjOlg] and the tetrahedral [ZnCU] have already been mentioned. Numerous hydroxo-complexes, foi example [ZnfOH) ], [Zn(OH)4] have been described. Additior. of excess ammonia to an aqueous Zn(II) solution produces the tetraamminozinc cation [Zn(N 113)4]-. Hence zinc tends to form 4-coordinate, tetrahedral or (less commonly) 6-coordinate octahedral complexes. 

In reactions (b) and (c) the hydrochloric and acetic acids formed are of course at once neutralised by the excess of ammonia. 

Oxamide differs from most aliphatic acid amides in being almost insoluble in water, and therefore can be readily prepared from the diethyl ester by Method 2(a). Place a mixture of 5 ml. of concentrated [d o-88o) ammonia solution and 5 ml. of water in a 25 ml. conical flask, for which a welTfitting cork is available. (The large excess of... 

Glycine is the simplest member of a large and very important class of compounds, the a-amino-carboxylic acids. TTiere are many different methods available for the synthesis of amino-acids, but glycine can be readily prepared by the action of an excess of ammonia on chloroacetic acid ... 

Sulphanilamide, the simplest member of a large series of bacteriostatic drugs, can readily be prepared by the following reactions. Acetanilide, when treated v ith an excess of chlorosulphonic acid, gives p-acetaniidobenzencsulphonyl chloride (Reaction A), w hich readily reacts with ammonia to give p-acetamido-benzenesulphonamide (Reaction H). The acetamido-group in the latter... 

Colorations or coloured precipitates are frequently given by the reaction of ferric chloride solution with.(i) solutions of neutral salts of acids, (ii) phenols and many of their derivatives, (iii) a few amines. If a free acid is under investigation it must first be neutralised as follows Place about 01 g. of the acid in a boiling-tube and add a slight excess of ammonia solution, i,e., until the solution is just alkaline to litmus-paper. Add a piece of unglazed porcelain and boil until the odour of ammonia is completely removed, and then cool. To the solution so obtained add a few drops of the "neutralised ferric chloride solution. Perform this test with the following acids and note the result ... 

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