ON FUEL ECONOMY. 259 



Appendix III. 



Memorand^nn upon the Skinningrove Process for the Production of 

 Alcohol from Coke Oven Gas. 



The following is a brief outline of the process devised by Messrs. Bury and 

 Ollander for the removal of ethylene from debenzolised coke oven gas and its 

 conversion into ethyl alcohol. 



The average amount of defines present in a debenzolised gas from a typical 

 Durham coking coal is usually between 2"0 and 2o per cent. They consist chiefly 

 of ethylene with small quantities of propylene and possibly other higher members 

 of the series. 



The process for their removal from tEe gas is based upon the well-known 

 fact that ethylene is absorbed by concentrated sulphuric acid forming ethyl 

 hydrogen sulphate, which may be subsequently hydrolyeed by the dilution of 

 the acid with water yielding ethyl alcohol and sulphuric acid. The sequence of 

 the reactions concerned may be represented by the following equations : — 



(a) C^Hi+H^SO^^ > 



.'SO,, 



C H 

 (6) ^ °NsOi-l-H20 = CjH50H+H2S04. 



The problem presented to the investigators was not only the determination 

 of the conditions under which 2 per cent, of ethylene in an industrial gas can 

 be rapidly absorbed by concentrated sulphuric acid so as to produce ethyl 

 hydrogen sulphate exclusively, but also how the much smaller quantities of 

 higher olefinas contained in the gas can be removed from it prior to the desired 

 absorption of ethylene. 



Laboratory experiments proved (i) that, although the absorption of ethylene 

 by concentrated sulphuric acid proceeds far too slowly at ordinary temperatures, 

 yet between 60° and 80° C, the time of contact required between the acid and 

 coke oven gas, in order to ensure the absorption of 70 per cent, of its total ethylene 

 content, need be no more than 2^ minutes, and (ii) that under such conditions 

 the only product formed is ethyl hydrogen sulphate. On the other hand, if the 

 temperature be allowed to exceed 80° C. some decomposition occurs and ethyl 

 ether is produced. 



The successful operation of such an absorption process on a large scale pre- 

 supposes the elimination from the crude gas of tars, ammonia, naphthalene, and 

 benzol hydrocarbons in the order named. At the Skinningrove Works the 

 Otto direct process is employed for this purpose. 



The next step consists in the successive elimination from the cooled and 

 debenzolised gas of (a) sulphuretted hydrogen, and (6) higher defines than 

 ethylene, together with most of its water vapour content. For the elimination 

 of the sulphuretted hydrogen it is proposed to make use of the well-known 

 reaction between sulphuretted hydrogen and sulphur dioxide gases :— 



2Hj +SO2 :s;Stl2K._0 + 3S. 



The advantage of such a procedure is that it would not only dispense with 

 the necessity of employing iron oxide purifiers (except perhaps as a final pre- 

 caution), but it would also enable the small amount of sulphur dioxide arising 

 from the reduction of the hot strong sulphuric acid during the later ethylene 

 absorption process to be utilised. 



Propylene and other higher olefinee are next removed by scrubbing the g-as 

 with an 80 per cent, sulphuric acid at the ordinary temperature in a tower on the 

 counter-current principle, which also effects the removal of about 97 per cent 

 of its water vapour content. The resulting cooled and dried gas ia then passed 



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