Ammonia synthesis stoichiometry

After desulfurization, steam is added and the mixture heated to 480 to 550°C before it is fed into the primary reformer. The gas leaving the primary reformer contains between 7 and 10% methane. This is removed in so-called secondary reformers in which the gas leaving the primary reformer is partially burnt with air in nickel catalyst-filled shaft furnaces (autothermal process), whereupon the temperature increases to ca. 1000°C. Under these conditions the methane reacts with the steam reducing the methane content in the synthesis gas to ca. 0.5 mole %. The quantity of air is adjusted to give the nitrogen to hydrogen ratio required for the stoichiometry of the ammonia synthesis. 

If oxygen-enriched air is u.sed, its quantity is adjusted to give the nitrogen to hydrogen ratio required for the stoichiometry of the ammonia synthesis. 

The ammonia synthesis reaction is represented by Eq. 11.6, which establishes the stoichiometry of 2 mol (volumes) of ammonia produced for each 4 mol (volumes) of reacting gases. 

Stoichiometry of ammonia synthesis (2.6.1), with side reaction (2.7.2). 

There is no necessary conne,qdon between order and the stoichiometric coefficients in the reaction equation that is, it is no j-equired that a and = tn reactiqn (275). For example, the stoichiometry of the ammonia-synthesis reaction is -f. 

The ammonia synthesis is carried out in the gas phase at 25°C, 1 bar, using an initial feed containing three moles of hydrogen for each mole of nitrogen. The stoichiometry for the reaction was determined in 7.4.2. In 10.3.3 we found the value of the equilibrium constant to be... 

Problem 14.9 a) Calculate the equilibrium constant at 1000 °C for ammonia synthesis in the stoichiometry written below ... 

FeO has three chemical characteristics, i.e., oxidative, non-stoichiometry and meta-stability. They must be taken seriously during the manufacture, reduction and application of Fei xO based ammonia synthesis catalyst. As shown in the researches on iron catalyst during the past century, the iron oxides precursor of the catalysts is Fe304 all along, so it has been studied intensively, while that of FeO is not. Hence, here is a detailed introduction to FeO. 

Figure 1.10 shows surface micrographs of CoMo intermetallic alloys after carburization in an attempt to synthesize a bimetallic (ternary) carbide. Such phases are of increasing interest as catalysts for a variety of industrial processes, including hydro-treating to remove S, N, and O impurities from fossil fuels, ammonia synthesis, water gas shift reaction to produce hydrogen, and fuel cell catalysts [44 7]. They are typically formed by gas reactions of complex oxide precursors or by molecular precursor or chemical synthesis [48-50] routes. The use of intermetallic precursors offers the potential to leverage a different set of precursor stoichiometries and structures to form new complex... 

The synthesis of 4-unsubstituted DHPs in a focused microwave reactor has been reported using alkyl acetoacetates and hexamethylenetetramine 19 as the source of both formaldehyde and ammonia, with additional ammonium acetate to maintain the stoichiometry [57], Irradiation for 100 s under solvent-free conditions gave, for example, 1,4-DHP 20 in 63% isolated yield (Scheme 5). 

Liquid ammonia is not a classical solvent for sulfur because it dissolves sulfur in the course of a reversible and slow disproportionation process as has been described earlier. Ammonia is a very useful solvent for the investigation of polysulfides because it allows their synthesis with an easy control of their stoichiometry. After evaporation of ammonia and drying under high vacuum, a solid with the overall composition M28 is obtained. The solid is either a polysulfide or a mixture of polysulfide (s) with sulfur, depending... 

Three important distinguishing facts concerning the synthesis of acetyl-P and formyl-P will be brought to mind (1) that unlike the synthesis of carbamyl-P, no ammonia is involved in the synthesis of ace-tyl-P or formyl-P (2) that Mn+2 rather than Mg 2 is the most active cation in acetyl-P and formyl-P synthesis and in ATP synthesis from acetyl-P (while Mg+2 is most active in the synthesis of carbamyl-P, Mn+2 is again more active in the utilization of ATP by the frog liver enzyme in the absence of ammonium ions) and (3) that the stoichiometry of the reaction with respect to ATP appears to differ with the product, one ATP being utilized per mole of formyl-P synthesized (evidence indicates that the same is the case for acetyl-P synthesis). 

The synthesis of the first dinuclear alumoxane (4) containing a terminal hydroxide was accomplished (26) soon after the discovery of aluminum dihydroxide 3, just by changing the reaction stoichiometry (Scheme 3). It is assumed that excess LAII2 generates LAl(OH)2 and LAI (0H)NH2. Condensation of the two leads to the elimination of ammonia and the formation of the alumoxane dihydroxide [LAl(0H)]2([r-0). 

Ammonia decomposition, on the other hand, may be carried out under more favorable conditions. Stoichiometry favors low pressure, 0 normal atmospheric-pressure equipment is sufficient. Equilibrium yields increase with temperalun and kinetic rates are measured with precision. This is why ammonia decomposition, which is less interesting, has historically received so much attention in the search for improved synthesis catalysts. ... 

Consider synthesis of ammonia from nitrogen and hydrogen carried out in the gas phase at 1 bar, 25°C. The stoichiometry for this reaction was determined in 7.4.2. At 25°C and a standard pressure = 1 bar, the JANAF tables [5] give the standard change in Gibbs energy to form one mole of ideal-gas NH3 from its elements that value is Ag° = -16.45 kJ/(mol ammonia formed). With this we can use (10.3.14) to obtain the value for K,... 

Anhydrous halogen derivatives of metals can be converted into metal alkoxides via reaction with either alkali metal alkoxides or with alcohols in the presence of ammonia. The reaction is usually carried out in other solvents than alcohols (hydrocarbon or ether ones) on cooling and with the amoimts of alcohols only slightly exceeding the stoichiometry. The reason is that oxo-alkoxides or oxo-alkoxide halides can otherwise be formed as impurities. This approach can be used successfully for synthesis of, for example, alkoxides of Sn(IV) [87], Bi (III) [114], and Fe(III) [82] ... 

Howev, at the molecular level, there is no such thing as half of a N2 molecule or half of a H2 molecule. Therefore, the above reaction, which describes the stoichiometry of the commercial synthesis of ammonia, cannot he elementary as written. 

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