Syngas from methane

Steam reforming (allothermal process) is the most widely used process for the production of syngas from methane. The important steam reforming reactions are shown in Reactions 2.1—2.3. Reaction 2.1 represents the endothermic steam reforming reaction where synthesis gas is produced in a 3 1 H2/CO ratio. 

Williams, K., LeClerc, C. A., Schmidt, L. D., Rapid lightoff of syngas from methane A transient product analysis, AIChE J., 51(1), 2005, 247-260. 

The oxygen plant accounts for about 55% of the investment for the production of syngas from methane. To lower these costs, Syntroleum have operated a demonstration unit in which air instead of oxygen is fed to a low pressure au-tothermal reformer (11). The problem, however, is that the syngas contains about 50% nitrogen and hence the partial pressures of the reactants in the low pressure downstream FT reactors are very low and so the reactor capacities too are low. The tail gas, after condensation of the liquid FT products, will contain about 85% nitrogen and so cannot be recycled to the reformers or be used as fuel gas. Unless demonstrated to be otherwise, the process does not appear to be competitive. 

In the preparation of syngas from methane, there is always some total oxidation of methane to CO2 and H2O as well as coke formation. Coke formation can be reduced by improving the catalytic selectivity, while CO2 and H2O can be reused in reforming reactions ... 

ICI Low Pressure Methanol A process for making methanol from methane and steam. The methanol is first converted to syngas by steam reforming at a relatively low pressure. The syngas is then converted to methanol over a copper-based catalyst ... 

Nitric acid is made from methane by first reacting CH4 with H2O to form syngas. Water is added to the CO + Hz mixture to form H2 and CO2 which is easily separated. Hydrogen is reacted with N2 from a liquid air plant. Ammonia is oxidized to NO over a Pt catalyst, and additional air is added to form NO2, and the product is dissolved in water. 

Modeling for Syngas from Steam Reforming of Methane... 

Raw syngas from the primary reformer furnace is a mixture of hydrogen, carbon monoxide, carbon dioxide and unreacted methane. A typical reformer outlet gas composition is shown in Table 1. This composition corresponds to a furnace outlet temperature of 1620 F, outlet pressure of 340 psig and a S/C ratio of 4.0 [1]. 

Recycling of all the CO2 in the syngas product from methane will yield a syngas with a H2/CO ratio close to the stoiciometric ratio of 3 1. To obtain lower ratios, supplemental CO2 is required. Imported CO2 is often used for syngas in the production of methanol and 0x0 alcohols. It is technically feasible to add supplemental CO2 to the reformer feed so that the final syngas product H2/CO ratio approaches 2 1 (this is described in more detail in Section III.C). However, obtaining ratios below 2 1 presents technical limitations and economic penalties. 

Similarly to the aforementioned reactions in the CH4-CO2 mixture, the reaction of methane and water vapor in thermal plasma leads to the production of syngas (H2, CO). Non-thermal plasma is also usually applied to produce the H2-CO mixture (see Chapter 10). As was demonstrated by Okazaki and Kishida (1999), application of non-thermal plasma permits the direct production of methanol from methane ... 

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