NEWS EDITION
MARCH 20,1936
105
The "Sulphidine'' Process for Recovering Sulfur Dioxide 1 Hans W e i d m a n n a n d Gerhard Roesner, Metallgesellschaft, A.-G., Frankfurt a. M . , Germany
NEW process for recovering sulfur A dioxide in pure form from dilute gaseous mixtures based on the use of an aqueous suspension of crude xylidine or its homologs in water has lately attracted favorable attention in several installations abroad, particularly in Germany and the Netherlands. The "sulphidine" process
into sulfite makes it soluble, and hence when the enriched liquor goes to the regenerator it consists of a water solution of xylidine sulfite. The xylidine used is the raw product of reduction of nitroxylene and may contain all of the six isomers. Toluidine may be similarly used. By conducting the absorption at 15°
C o m m e n d a b l e Cooperation A MEMBER, who had found it necessary to
resign temporarily from the AMERICAN
CHEMICAL SOCIETY, found upon requesting
reinstatement that he could not qualify under present admission rules for full membership. He has accepted the junior status, and in so doing has the following to say:
I was fully conversant with the SOCIETY'S present bimembership plan when making my application for reinstatement and therefore did not expect to be admitted to full membership. You may convey m y respects to the membership committee and say to them that I hold no ill will against them. I t is perfectly right and proper that a society or organization which is working for the advancement of science endeavor to stimulate such by inducing a higher standard of training among its members. One of the ways of accomplishing this is occasion ally and gradually to raise the requirement for membership. Anyone who has the true spirit of progress but who through force of circumstances in the past was not able to be prepared for the advancing requirements of the present will not feel grieved but rather will rejoice that progress is still attainable.
An example of commendable coopera tion indeed. T e n t h Birthday Celebration | ^ Η Ε tenth anniversary of the establishJL ment of the Division of Organic and Fibrous Materials of the National Bureau of Standards was celebrated on the eve ning of March 5 by an open house in the Industrial Building of the bureau. War ren E. Emley, who has been chief of the division from the beginning, acted as host to the director of the bureau, Lyman J. Briggs, and the bureau's staff, as well as to a considerable number of invited guests representing the Department ci Commerce and scientific and technical bureaus and organizations in Washington. The members of the staff, which num bers 66, 14 of whom have been with the division since it was started in 1926, helped to give an idea of the wide variety of work carried on. Among the interest ing exhibits were the experimental paper mill in operation; the machines for testing the durability of tires, shoes, and hosiery; and the equipment for determining the best conditions for the preservation of important records. The newest section is studying transparent organic plastics for use as windows in airplanes, and had an exhibit showing how the resistance of these materials to abrasion and weathering is studied. The number and variety of in struments (many of which have been de veloped by the bureau), used in deter mining the properties of organic and fibrous materials, was a surprise even to members of the other divisions of the bureau. Γ
" S U L P H I D I N E " EXPERIMENTAL PLANT
was developed by the Gesellschaft fur Chemische Industrie in Basel and the Metallgesellschaft, A.-G., of Frankfurt a. M. 2 I t has pronounced advantages over other previously proposed processes in the higher absorptive capacity of the solution, especially when dilute gaseous mixtures are treated, and in the ease with which sulfate can be removed from the absorbent solution without loss of the aromatic amine. The method consists of washing gases containing sulfur dioxide (freed from dust, sulfur, and sulfur trioxide) in a scrubber with a 1 t o 1 mixture of xylidine and water, adding sodium, carbonate (or sulfite) to convert any xylidine sulfate present to sodium sulfate, and heating the enriched liquor t o 80° to 100° C. to drive off the sulfur dioxide in pure form. The re moval of sulfate from the solution is ac complished, wlien this has accumulated to a point justifying it, by withdrawing the aqueous layer (in which the xylidine is only slightly soluble on account of its dissolved salt content), and replacing it with fresh water. The original mixture of xylidine and water consists of two layers, but during the absorption of sulfur dioxide the conversion of the oily xylidine 1 Abstracted from Afetallges. Periodic Rev., No. 11, 1935. « German Patents, 557,723 (March 9, 1930) and 606,447 (May 7, 1933). French Patent 695,500 (May 13. 1930). Swiss Patent 142,731 (October 15, 1930). U. S. Patent 1,893,385 (January 3, 19333-
to 3 0 ° C , the exit gases from the absorbers can be reduced to as low as 0.1 per cent sulfur dioxide, thus giving an efficiency above 98 per cent with a raw gas contain ing as much as 7 per cent sulfur dioxide. The regeneration of the sulfur dioxide is substantially complete as the process is operated and the gas is better than 99 per cent pure. Before compression it is washed with sulfuric acid to free it from traces of xylidine vapors and dried. The amount of xylidine vapor escaping from the absorbers with the waste gases is rather high (2.5 grams per cubic meter at 20° to 25° C.) and these must be washed with alkaline bisulfite or sulfuric acid solu tion, from which the xylidine is recovered in the desulfation of the absorbent solu tion. The advantage of the process rests in the ability of the absorbent to utilize gases of even low concentration. In the Norddeutsche Affinerie in Hamburg waste gases containing 0.5 to 8.0 per cent sul L u c a s A w a r d f o r A c h i e v e m e n t i n fur dioxide (average 3.6 per cent) from Petroleum Engineering treating copper matte in converters are HE American Institute of Mining and successfully used as sources of 100 per Metallurgical Engineers has authorized cent sulfur dioxide. the appointment of a committee to draw up rules of procedure under which awards HIPMENTS of chemicals and related prod can be made to petroleum engineers for ucts from Continental United States outstanding contributions to the art of to the territories of Hawaii, Puerto Rico, finding and producing oil and gas. The and Alaska continued at high levels during awards will be sponsored by the Petroleum 1935 and aggregated $11,602,600 in value, Division of the institute and are in memory compared with $10,950,280 for 1934, ac of Anthony F. Lucas, a pioneer in the oil cording to the Commerce Department's industry. The first medal is to be preChemical Division. sented in February, 1937.
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