Partial oxidation (POX) is a type of

chemical reaction A chemical reaction is a process that leads to the IUPAC nomenclature for organic transformations, chemical transformation of one set of chemical substances to another. Classically, chemical reactions encompass changes that only involve the pos ...

. 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 distinction is made between ''thermal partial oxidation'' (TPOX) and ''catalytic partial oxidation'' (CPOX).

Principle

Partial oxidation is a technically mature process in which

natural gas Natural gas (also called fossil gas or simply gas) is a naturally occurring mixture of gaseous hydrocarbons consisting primarily of methane in addition to various smaller amounts of other higher alkanes. Low levels of trace gases like carbo ...

or a heavy hydrocarbon fuel ( heating oil) is mixed with a limited amount of oxygen in an exothermic process. * General reaction: + \frac\mathit -> \mathit + \frac\mathitH2 * Idealized reaction for heating oil: + 6O2 -> + 12H2 * Idealized reaction for coal: + 12O2 -> + 6H2 The formulas given for coal and heating oil show only a typical representative of these complex fuels. Water may be added to lower the combustion temperature and reduce soot formation. Yields are below stoichiometric due to some fuel being fully combusted to carbon dioxide and water.

TPOX

TPOX (''thermal partial oxidation'') reaction temperatures are dependent on the air-fuel ratio or oxygen-fuel ratio. Typical reaction temperatures are 1200

°C The degree Celsius is the unit of temperature on the Celsius scale (originally known as the centigrade scale outside Sweden), one of two temperature scales used in the International System of Units (SI), the other being the Kelvin scale. The ...

and above.

CPOX

In CPOX (''catalytic partial oxidation'') the use of 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 ...

reduces the required temperature to around 800°C – 900°C. The choice of reforming technique depends on the sulfur content of the fuel being used. CPOX can be employed if the sulfur content is below 50 ppm. A higher sulfur content can poison the catalyst, so the TPOX procedure is used for such fuels. However, recent research shows that CPOX is possible with sulfur contents up to 400ppm.Electricity from wood through the combination of gasification and solid oxide fuel cells
Ph.D. Thesis by Florian Nagel, Swiss Federal Institute of Technology Zurich, 2008

History

1926 – Vandeveer and Parr at the

University of Illinois The University of Illinois Urbana-Champaign (U of I, Illinois, University of Illinois, or UIUC) is a public land-grant research university in Illinois in the twin cities of Champaign and Urbana. It is the flagship institution of the Univer ...

used oxygen to replace air.''Industrial Gas Handbook'', Frank G. Kerry, p. 230

References

{{reflist Chemical reactions Hydrogen production Industrial gases Redox

Principle

TPOX

CPOX

History

See also

References