Claus process

Piles of sulfur produced in Alberta by the Claus process awaiting shipment at docks in Vancouver, Canada.

The Claus process is the most significant gas desulfurizing process, recovering elemental sulfur from gaseous hydrogen sulfide. First patented in 1883 by the chemist Carl Friedrich Claus, the Claus process has become the industry standard.

The multi-step Claus process recovers sulfur from the gaseous hydrogen sulfide found in raw natural gas and from the by-product gases containing hydrogen sulfide derived from refining crude oil and other industrial processes. The by-product gases mainly originate from physical and chemical gas treatment units (Selexol, Rectisol, Purisol and amine scrubbers) in refineries, natural gas processing plants and gasification or synthesis gas plants. These by-product gases may also contain hydrogen cyanide, hydrocarbons, sulfur dioxide or ammonia.

Gases with an H2S content of over 25% are suitable for the recovery of sulfur in straight-through Claus plants while alternate configurations such as a split-flow set up or feed and air preheating can be used to process leaner feeds.[1]

Hydrogen sulfide produced, for example, in the hydro-desulfurization of refinery naphthas and other petroleum oils, is converted to sulfur in Claus plants.[2] The reaction proceeds in two steps:

2 H2S + 3 O2 → 2 SO2 + 2 H2O
4 H2S + 2 SO2 → 3 S2 + 4 H2O

The vast majority of the 64,000,000 tonnes of sulfur produced worldwide in 2005 was byproduct sulfur from refineries and other hydrocarbon processing plants.[3][4][5] Sulfur is used for manufacturing sulfuric acid, medicine, cosmetics, fertilizers and rubber products. Elemental sulfur is used as fertilizer and pesticide.

  1. ^ Gas Processors Association Data Book, 10th Edition, Volume II, Section 22
  2. ^ Gary, J.H.; Handwerk, G.E. (1984). Petroleum Refining Technology and Economics (2nd ed.). Marcel Dekker, Inc. ISBN 0-8247-7150-8.
  3. ^ Sulfur production report by the United States Geological Survey
  4. ^ Discussion of recovered byproduct sulfur
  5. ^ Der Claus-Prozess. Reich an Jahren und bedeutender denn je, Bernhard Schreiner, Chemie in Unserer Zeit 2008, Vol. 42, Issue 6, Pages 378-392.