Water gas is a synthesis gas, containing carbon monoxide and hydrogen. It is a useful product but requires careful handling because of the risk of carbon monoxide poisoning. The gas is made by passing steam over red-hot coke:

C + H₂O → CO + H₂

The reaction is endothermic so the coke must be continually re-heated to keep the reaction going. This was usually done by alternating the steam stream with an air stream.

Contents 1 History 2 Lowe's gas process 3 Variations 4 References 5 See also

[edit] History

The water-gas shift reaction was discovered by Italian physicist Felice Fontana in 1780. Water gas had been made in England since 1828 by blowing steam through red-hot coke, this water gas was carburized by petrol according to a process invented by Thomson and Hind (Singer 119). Charles Singer also states in his "A History of Technology" that, in the United States, natural gases were often used for carburizing (Singer 119).

[edit] Lowe's gas process

In 1873, Thaddeus S. C. Lowe developed and patented the water gas process by which large amounts of hydrogen gas could be generated for residential and commercial use in heating and lighting. Unlike the common coal gas, or coke gas which was used in municipal service, this gas provided a more efficient heating fuel. The process used the water gas shift reaction:

CO + H₂O → CO₂ + H₂

The process was discovered by the passing of high-pressure steam over hot coal, the major source of coke gas. Lowe's process improved upon the chimney systems by which the coal could remain superheated thereby maintaining a consistently high supply of the gas. This process created a thermo-chemical reaction of applying hydrogen, in the steam, to carbon monoxide, in the coke gas. The reaction produced carbon dioxide and pure hydrogen which after a process of cooling and "scrubbing," passing through water vapor, left just a pure hydrogen gas.

The process spurred on the industry of gas manufacturing, and gasification plants were established quickly along the Eastern seaboard of the United States. Similar processes, like the Haber Process, led to the manufacture of ammonia (NH₃) by the combining of nitrogen, found in air, with high volumes of hydrogen. This spurred on the refrigeration industry which long used ammonia as its refrigerant. Prof. Lowe also held several patents on artificial ice making machines, and was able to run successful businesses in cold storage as well as products which operated on hydrogen gas.

[edit] Variations

Water gas had a lower calorific value than coal gas so the calorific value was often boosted by passing the gas through a heated retort into which oil was sprayed. The resulting mixed gas was called carburetted water gas.

Semi-water gas is a mixture of water gas and producer gas made by passing a mixture of air and steam through heated coke. The heat generated when producer gas is formed keeps the temperature of the coke high enough to allow water gas to be formed.

Pure hydrogen can be obtained from water gas by using the Water gas shift reaction.

[edit] References

• Mellor, J.W., Intermediate Inorganic Chemistry, Longmans, Green and Co., 1941, pp 210-211
• Adlam, G.H.J. and Price, L.S., A Higher School Certificate Inorganic Chemistry, John Murray, 1944, page 309
• Singer, Charles Joseph; Raper, Richard. A history of technology : edited by Charles Singer ... [et al.]. Clarendon Press, 1954-1978. History e-book project.. ACLS Humanities E-book. Vol 5. "The use of mineral oil" p. 119

[edit] See also

• Gasification
• Gasification, gasifier, pyrolysis, pyrolyser
• Lane hydrogen producer
• Linde-Frank-Caro process
• Town gas
• Wood gas
• Mond gas