A methane reformer is a device based on

steam reforming Steam reforming or steam methane reforming (SMR) is a method for producing syngas (hydrogen and carbon monoxide) by reaction of hydrocarbons with water. Commonly natural gas is the feedstock. The main purpose of this technology is hydrogen product ...

autothermal reforming Steam reforming or steam methane reforming (SMR) is a method for producing syngas (hydrogen and carbon monoxide) by reaction of hydrocarbons with water. Commonly natural gas is the feedstock. The main purpose of this technology is hydrogen produc ...

partial oxidation Partial oxidation (POX) is a type of chemical reaction. It occurs when a substoichiometric fuel-air mixture is partially combusted in a reformer, creating a hydrogen-rich syngas which can then be put to further use, for example in a fuel cell. A d ...

and is a type of

chemical synthesis As a topic of chemistry, chemical synthesis (or combination) is the artificial execution of chemical reactions to obtain one or several products. This occurs by physical and chemical manipulations usually involving one or more reactions. In mod ...

which can produce pure

hydrogen Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-toxic ...

gas from

methane Methane ( , ) is a chemical compound with the chemical formula (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The relative abundance of methane on Ea ...

using a

catalyst Catalysis () is the process of increasing the rate of a chemical reaction by adding a substance known as a catalyst (). Catalysts are not consumed in the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recyc ...

. There are multiple types of reformers in development but the most common in industry are autothermal reforming (ATR) and steam methane reforming (SMR). Most methods work by exposing methane to a catalyst (usually

nickel Nickel is a chemical element with symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel is a hard and ductile transition metal. Pure nickel is chemically reactive but large pieces are slow ...

) at high temperature and pressure.

Steam reforming

Steam reforming (SR), sometimes referred to as steam methane reforming (SMR) uses an external source of hot gas to heat tubes in which a catalytic reaction takes place that converts steam and lighter hydrocarbons such as methane,

biogas Biogas is a mixture of gases, primarily consisting of methane, carbon dioxide and hydrogen sulphide, produced from raw materials such as agricultural waste, manure, municipal waste, plant material, sewage, green waste and food waste. It is a ...

or refinery feedstock into hydrogen and

carbon monoxide Carbon monoxide (chemical formula CO) is a colorless, poisonous, odorless, tasteless, flammable gas that is slightly less dense than air. Carbon monoxide consists of one carbon atom and one oxygen atom connected by a triple bond. It is the simple ...

(syngas). Syngas reacts further to give more hydrogen and carbon dioxide in the reactor. The carbon oxides are removed before use by means of

pressure swing adsorption Pressure swing adsorption (PSA) is a technique used to separate some gas species from a mixture of gases (typically air) under pressure according to the species' molecular characteristics and affinity for an adsorbent material. It operates at ne ...

(PSA) with molecular sieves for the final purification. The PSA works by adsorbing impurities from the syngas stream to leave a pure hydrogen gas. :CH₄ + H₂O (steam) → CO + 3 H₂ Endothermic :CO + H₂O (steam) → CO₂ + H₂ Exothermic

Autothermal reforming

Autothermal reforming Steam reforming or steam methane reforming (SMR) is a method for producing syngas (hydrogen and carbon monoxide) by reaction of hydrocarbons with water. Commonly natural gas is the feedstock. The main purpose of this technology is hydrogen produc ...

(ATR) uses oxygen and carbon dioxide or steam in a reaction with methane to form syngas. The reaction takes place in a single chamber where the methane is partially oxidized. The reaction is exothermic due to the oxidation. When the ATR uses carbon dioxide the H₂:CO ratio produced is 1:1; when the ATR uses steam the H₂:CO ratio produced is 2.5:1 The reactions can be described in the following equations, using CO₂: : 2 CH₄ + O₂ + CO₂ → 3 H₂ + 3 CO + H₂O And using steam: : 4 CH₄ + O₂ + 2 H₂O → 10 H₂ + 4 CO The outlet temperature of the syngas is between 950-1100 °C and outlet pressure can be as high as 100 bar. The main difference between SMR and ATR is that SMR only uses oxygen via air for combustion as a heat source to create steam, while ATR directly combusts oxygen. The advantage of ATR is that the H₂:CO can be varied, this is particularly useful for producing certain second generation biofuels, such as DME which requires a 1:1 H₂:CO ratio.

Partial oxidation

{{main, Partial oxidation Partial oxidation (POX) is a type of chemical reaction. It occurs when a substoichiometric fuel-air mixture is partially combusted in a reformer, creating a hydrogen-rich syngas which can then be put to further use.

Advantages and disadvantages

The capital cost of steam reforming plants is prohibitive for small to medium size applications because the technology does not scale down well. Conventional steam reforming plants operate at pressures between 200 and 600 psi with outlet temperatures in the range of 815 to 925 °C. However, analyses have shown that even though it is more costly to construct, a well-designed SMR can produce hydrogen more cost-effectively than an ATR for smaller applications.AIA: Software Analyzes Cost of Hydrogen Production – Archives – ASSEMBLY
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References

External links