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Osaka Gas’ residential polymer electrolyte fuel cell (PEFC) cogeneration system
About the fuel processing system


Return to the process flow of the fuel processing system

In case the fuel gas contains sulfur compounds, the performance of the fuel processing system decreases; for this reason, the desulfurizer removes the sulfur components.

Desulfurization can be performed in three different methods described below:

Conventional desulfurization by means of hydrogenation reaction

(1) A sulfur compound reacts with hydrogen on catalyst (Ni-Mo-based; Co-Mo-based) to be converted into hydrogen sulfide (at 250˚C to 400˚C).
(2) Hydrogen sulfide is taken into zinc oxide to be removed (350˚C to 400˚C)
  • A method generally adopted in hydrogen production plants
  • Have to wait until the temperature of the hydrogenation catalyst layer rises.
  • Sulfur content cannot be removed below 0.1ppm.

Normal temperature desulfurization


Sulfur compound is removed with an adsorbent like zeolite (at room temperature)

  • Operating at room temperature allows a simple system configuration.
  • With sulfur compound being adsorbed simply on the surface of the desulfurizer, a large amount of adsorbent are required for longer operation.
  • Fluctuations in the conditions, such as temperature, pressure, and fuel gas will cause the adsorbed sulfur compound to be released.

Osaka Gas’ unique ultra-high-level desulfurization technology


Ultra-high-level desulfurization has both features of a hydrogenation desulfurization and normal temperature desulfurization.

  • This technology allows operation at room temperatures; for this reason, it is not necessary to wait for the temperature of the desulfuriser to rise. (The desulfuriser is normally used at a temperature of about 250˚C in practice.)
  • On account of its extremely strong affinity with sulfur, sulfer content is reduced to below a ppb (one thousandth of a ppm) level
  • Only one liter of ultra-high-level desulfuriser is enough to operate a 1-kW PEFC system for 90,000 hours.
  • The adsorption capability is not affected by humidity.
  • COS, which cannot be removed by normal temperature desulfurization, can be removed easily by this method.
  • Composed of inexpensive materials excluding noble metals; this method makes it possible to reduce costs.
Click here to look at Osaka Gas’ fuel processing system for ENE・FARM Osaka Gas’ unique technology that integrates all reactors into one package, enables the CO concentration to be reduced below 1 ppm.。

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