Ammonia by steam reformation

Figure 8.3.1 is a typical process diagram for tlie production of ammonia by steam reforming. Tlie first step in tlie preparation of tlie synthesis gas is desulfurization of the hydrocarbon feed. Tliis is necessary because sulfur poisons tlie nickel catalyst (albeit reversibly) in tlie reformers, even at very low concentrations. Steam reforming of hydrocarbon feedstock is carried out in tlie priiiiiiry and secondary reformers. 

The steam-methane reforming process produces ammonia by steam reforming natural or refinery gas under pressure, followed by carbon monoxide shift, purification of raw synthesis gas, and ammonia synthesis. In the process, saturated and unsaturated hydrocarbons are decomposed by steam according to the basic equation ... 

A simplified flow diagram for the production of ammonia by steam reforming of natural gas or naphtha is shown in Figure 6.3. In the following discussion, each of the steps will be discussed in the sequence in which they occur. 

Methane. The largest use of methane is for synthesis gas, a mixture of hydrogen and carbon monoxide. Synthesis gas, in turn, is the primary feed for the production of ammonia (qv) and methanol (qv). Synthesis gas is produced by steam reforming of methane over a nickel catalyst. 

Over 90% of all carbon dioxide is made by steam-reforming of hydrocarbons, and much of the time natural gas is the feedstock. It is an important by-product of hydrogen and ammonia manufacture. 

As we learned in Chapters 3 and 4, many inorganic compounds, not just ammonia, are derived from synthesis gas, made from methane by steam-reforming. In the top 50 this would include carbon dioxide, ammonia, nitric acid, ammonium nitrate, and urea. No further mention need be made of these important processes. We discussed MTBE in Chapter 7, Section 4, and Chapter 10, Section 9, since it is an important gasoline additive and C4 derivative. In Chapter 10, Section 6, we presented -butyraldehyde, made by the 0x0 process with propylene and synthesis gas, which is made from methane. In Chapter 11, Section 8, we discussed dimethyl terephthalate. Review these pertinent sections. That leaves only two chemicals, methanol and formaldehyde, as derivatives of methane that have not been discussed. We will take up the carbonylation of methanol to acetic acid, now the most important process for making this acid. Vinyl acetate is made from acetic... 

The methanation reaction is primarily used to remove any traces of CO and C02 in the hydrogen feed gas for ammonia synthesis. The reaction has been known for more than a century [141]. This reaction has found renewed interest in connection with the transformation of coal to natural gas. The hydrogen for ammonia synthesis is here normally produced by steam reforming with subsequent water gas... 

It is also anticipated that this plant will be part of a larger chemical complex. Ammonia will be produced by steam reforming of natural gas. The nitric acid plant will take a portion of the ammonia product, and nitric acid and ammonia will then be used to produce ammonium nitrate. 

The process for ammonia manufacture will vary somewhat with the source of hydrogen, but the majority of ammonia plants generate the hydrogen by steam reforming natural gas or hydrocarbons such as naphtha (Fig. 2). 

If the hydrogen is made by steam reforming, air is introduced at the secondary reformer stage to provide nitrogen for the ammonia reaction. The... 

The latest improvements in ammonia production by steam reforming of natural gas indode the foDowing ... 

Based on pure methane, it is possible to formulate a stoichiometric equation (95) for ammonia production by steam reforming ... 

The production of hydrogen and synthesis gas mixtures (CO/H2) from methane and higher hydrocarbons by steam reforming involves numerous reaction steps with different catalysts. The synthesis of ammonia and the oxidation of SO2 to SO3 are long-known equUibrium reactions in which the target product is removed from the product stream and the unchanged starting material is recycled. 

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