Difference Between Syngas and Water Gas

Main Difference – Syngas vs Water Gas

Syngas and water gas are two types of fuel gases. Syngas, also known as synthetic gas, is composed of hydrogen, carbon monoxide, and very often some carbon dioxide. Water gas consists mainly of carbon monoxide and hydrogen and is produced from syngas. These fuel gases are produced from different processes. The main difference between Syngas and water gas is that Syngas is composed of carbon dioxide whereas water gas has no carbon dioxide.

Key Areas Covered

1. What is Syngas
     – Definition, Production, Uses
2. What is Water Gas
     – Definition, Production, Different Types
3. What is the Difference Between Syngas and Water Gas
     – Comparison of Key Differences

Key Terms: Carbon Dioxide, Carbon Monoxide, Coal, Fuel, Gasification, Hydrogen, Syngas, Water Gas

Difference Between Syngas and Water Gas - Comparison Summary

What is Syngas

Syngas is the short name used for synthesis gas, which is mainly composed of carbon monoxide (CO), carbon dioxide (CO2) and hydrogen. It is a fuel gas mixture. Syngas is a product of gasification of a carbon-containing fuel. Some examples for gasification process that give syngas include gasification of coal emissions, steam reforming of coke, etc.

The chemical composition of syngas varies based on the raw materials used in its production. However, syngas produced by coal gasification generally contains following proportions of each component.

  • Carbon monoxide (30-60%)
  • Hydrogen (25-30%)
  • Carbon dioxide (5-15%)
Difference Between Syngas and Water Gas

Figure 1: Coal Gasification produces Syngas

Syngas has many important applications: as an intermediate in generating synthetic natural gas, to create ammonia and methanol, to create synthetic petroleum to be used as a lubricant or fuel. Syngas cannot be burnt directly. It is used indirectly as a fuel source.

What is Water Gas

Water gas is a combustion fuel containing carbon monoxide (CO) and hydrogen gas (H2). Water gas is produced from syngas. The process of production includes passing steam over heated hydrocarbons. A reaction takes place between steam and hydrocarbons, giving syngas. Water gas is produced by reducing the carbon dioxide level in syngas and enriching it with more hydrogen. The major reaction used in producing syngas from water gas is water-gas shift reaction (given below). 

CO + H2O → CO2 + H2

Main Difference - Syngas vs Water Gas

Figure 1: Associative and Redox Mechanism of the Water Gas Shift

There are few types of water gas as follows.

  • Carburetted water gas – this form of water gas is made by passing the gas through a heated retort, into which oil is sprayed. This is done to boost the heat of combustion of water gas.
  • Semi-water gas – this form of gas is a mixture of producer gas and water gas. Producer gas is a mixture of carbon dioxide, carbon monoxide, hydrogen and nitrogen gas.

Difference Between Syngas and Water Gas

Definition

Syngas: Syngas is the short name used for synthesis gas which is mainly composed of carbon monoxide (CO), carbon dioxide (CO2) and hydrogen.

Water Gas: Water gas is a combustion fuel containing carbon monoxide (CO) and hydrogen gas (H2).

Composition

Syngas: Syngas contains carbon monoxide, carbon dioxide and hydrogen.

Water Gas: Water gas contains carbon monoxide and hydrogen gas.

Production

Syngas: Syngas is produced via gasification of a carbon-containing fuel.

Water Gas: Water gas is produced from syngas using water-gas shift reaction.

Conclusion

Syngas and water gas are used as fuel gases. Syngas is a product obtained from gasification of carbon-containing materials such as coal. Water gas is produced from syngas.  The main difference between Syngas and water gas is that Syngas is composed of carbon dioxide whereas water gas has no carbon dioxide.

Reference:

1. Helmenstine, Anne Marie. “Water Gas Definition.” ThoughtCo, Aug. 9, 2017, Available here.
2. “Syngas.” Wikipedia, Wikimedia Foundation, 22 Jan. 2018, Available here.
3. “What is Syngas.” Biofuel.org.uk, Available here.

Image Courtesy:

1. “Gasifier types” By Kopiersperre – Own work (CC BY-SA 3.0) via Commons Wikimedia
2. “WGS mechanism” By Zwickipedia – Own work (CC BY-SA 3.0) via Commons Wikimedia

About the Author: Madhusha

Madhusha is a BSc (Hons) graduate in the field of Biological Sciences and is currently pursuing for her Masters in Industrial and Environmental Chemistry. Her interest areas for writing and research include Biochemistry and Environmental Chemistry.

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