3007.     SABLATNÖG, A.  [Purification of Synthesis Gases.]  Österr. Chem.-Ztg., vol. 51, 1950, pp. 198-201, 220-233, 242-244; Chem. Abs., vol. 45, 1951, p. 4022.

        In cleaning water gas for use in the Fischer-Tropsch synthesis, investigation was made of various purification masses to remove the so-called condensates that passed the usual purifiers and were present in the gas in a concentration of about 1 gm. per m.³  The mode of origin, the thermal stability, and the constituents of the condensates are discussed.  The water-gas process of Koppers and Didier-Bubiag is described, and it is shown that the amount and composition of the condensates vary widely according to the process used, when the same brown coal was used for gasification.  Four purification masses were investigated:  (1) A mixture of Fe oxide and Na₂CO₃ -- this mixture does not remove all organic S compounds; thiophenes especially pass almost undecomposed, and gum-forming hydrocarbons always occur in the gas.  (2) Active C -- complete removal of gum formers and H₂S could be obtained and the organic S content was down to 0.01 gm. per m.³ synthesis gas.  The method, however, was objectionable because the active C must be regenerated with a loss of absorption power after each regeneration.  (3) Granular coke from brown coal -- this cheap material almost equaled active C in purification power, but the service time was very short, so that replacements were often necessary.  (4) Addition of finely powdered coke from brown coal to the synthesis gas -- this method proved satisfactory and economical.  With a gas flow of 50-100 m.³ per hr. the condensates with a concentration of 1 gm. per m.³ could be entirely removed by adding 30 gm. powdered brown coal coke per m.³ of gas, washed out after a contact time of 2-3 sec.  The H₂S must be oxidized first by adding 1% air and then removed.  The absorption temperature should not be higher than 30° if complete absorption is desired.  Finally the method was tested in a large-capacity water-gas plant by using the Didier-Bubiag process.  The conditions here were not so favorable as in the pilot plant.  The gas had a powdered coke content of only 1-2 gm. per m.³, the temp. was 50°-60°, and the contact time 1 sec.  Even under these conditions the condensates concentration dropped from 0.1-1.5 gm. per m.³ to 0.2-0.3 gm.  These residual condensates can only be removed with a higher coke-dust content, a longer contact time, and lower absorption temperature.