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The chemistry of 'doctor sweetening' was described in detail by G. Wendt and S. Diggs in 1924. They also showed that the lead oxide solution brought about oxidation of the mercaptans to the corresponding organic disulfides, which are comparatively odourless. Lead oxide (litharge) dissolves in
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When this alkaline solution is agitated with petroleum, the two liquids do not dissolve in one another, but any mercaptan in the oil will unite with an equivalent amount of the lead (which then passes into the petroleum) to form what is called a lead mercaptide, soluble in the oil:
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If the mixture is now treated with powdered sulfur, which has a high affinity for lead, a black suspension of lead sulfide forms, and conversion of the mercaptide into a so-called disulfide (which remains in the oil) is induced:
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It is evident that the process does not remove the sulfur from the oil but even may increase the sulfur content if too much powdered sulfur is added, and some of the lead may remain in the petroleum.
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With no sulfur added, but in the presence of atmospheric oxygen, the same conversion occurs, but only slowly, and probably not completely:
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if, after shaking with sodium plumbite solutions, the addition of powdered sulfur fails to produce a dark precipitate of lead sulfide.
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reasonably concentrated solutions of sodium hydroxide or potassium hydroxide owing to formation of a soluble compound, sodium
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199:{\displaystyle {\ce {{\overset {sour~gasoline}{2RSH}}+{Na2PbO2}+S->{\overset {alkyl~disulfide}{R-S-S-R}}+{PbS}+2NaOH}}}
720:
McGraw-Hill
Dictionary of Scientific and Technical Terms, 6th edition, published by The McGraw-Hill Companies, Inc., 2003
645:
for the sweetness or sourness of gasoline (i.e., the extent of sulfur contamination). A gasoline is described as
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Fortschritte auf dem
Gebiete der Mineralöle. Die technische Entwicklung der Erdölindustrie nach dem Kriege
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16:
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40:
into disulfides. Sulfur compounds darken gasoline, give it an offensive odor and increase toxic
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680:, Angewandte Chemie, Band 42, Ausgabe 20, p. 508-518, WILEY-VCH Verlag GmbH, May 18, 1929
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Tetraethyllead
Susceptibilities of Gasoline Doctor Treatment vs. Caustic Washing
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661:
Petroleum deodorized: Early canadian history of the âdoctor sweeteningâ process
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47:
These sulfur compounds can be removed with the following chemical reactions:
628:{\displaystyle {\ce {2(RS)2Pb + 4NaOH + O2 -> 2RS-SR + 2Na2PbO2 + 2H2O}}}
33:
687:, American Artisan and Patent Record (New York), new series 5, p. 310, 1867
216:
694:, Industrial and Engineering Chemistry, Ausgabe 16, pp. 1113-1115, 1924
733:, Industrial and Engineering Chemistry, Ausgabe 16, p. 1113-1115, 1924
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20:
Doctor
Sweetening Process; version as patented by Kalinowsky (1954)
15:
664:, Annals of Science, Vol. 48, Issue 2, Taylor & Francis, 1991
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engine emissions. However, this process only reduces the odor.
394:{\displaystyle {\ce {2RSH + Na2PbO2 -> (RS)2Pb + 2NaOH}}}
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The
Chemistry of "Sweetening" in the Petroleum Industry
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The
Chemistry of "Sweetening" in the Petroleum Industry
295:{\displaystyle {\ce {PbO + 2NaOH -> Na2PbO2 + H2O}}}
760:
Saeid
Mokhatab; William A. Poe; J. G. Speight (2006).
475:{\displaystyle {\ce {-(RS)2Pb + S -> RS-SR + PbS}}}
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Handbook of natural gas transmission and processing
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641:The described chemistry is also the basis of the
766:. Gulf Professional Publishing. pp. 397â.
750:, "Doctor sweetening process using sulfur"
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667:L. M. Henderson, W. B. Ross, C. M. Ridgway:
673:, Ind. Eng. Chem., 1939, 31 (1), p. 27â30
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703:, US patent 2871187 January 27, 1957
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210:Chemistry of the process
127:in the presence of NaOH
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803:Oil refining
777:. Retrieved
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647:doctor sweet
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643:doctor test
792:Categories
708:References
653:Literature
34:mercaptans
562:−
551:⟶
459:−
452:⟶
418:−
354:⟶
244:⟶
172:disulfide
157:−
149:−
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779:3 August
217:plumbite
122:→
77:gasoline
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754:
169:
74:
166:alkyl
781:2010
768:ISBN
532:NaOH
388:NaOH
241:NaOH
193:NaOH
71:sour
24:The
590:PbO
469:PbS
342:PbO
322:RSH
261:PbO
231:PbO
182:PbS
101:PbO
66:RSH
36:in
794::
577:Na
566:SR
558:RS
522:Pb
506:RS
463:SR
455:RS
443:Pb
427:RS
378:Pb
362:RS
329:Na
248:Na
219::
88:Na
783:.
622:O
614:2
610:H
605:2
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161:R
153:S
145:S
137:R
117:S
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105:2
92:2
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62:2
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