Carbonyl sulfide removal

Solid-Bed Caustic Treatment. SoHd-bed caustic units utilizing methanol [67-56-1] injection into the LPG feed stream can be used for carbonyl sulfide removal. The methanol—caustic solution must be drained periodically from the beds and discarded. When the soHd bed is exhausted, the spent caustic must be discarded and replaced. The LPG from the treater has a low enough water content to meet the propane specification. 

Conversion of carbon in the coal to gas is very high. With low rank coal, such as lignite and subbituminous coal, conversion may border on 100%, and for highly volatile A coals, it is on the order of 90—95%. Unconverted carbon appears mainly in the overhead material. Sulfur removal is faciUtated in the process because typically 90% of it appears in the gas as hydrogen sulfide, H2S, and 10% as carbonyl sulfide, COS carbon disulfide, CS2, and/or methyl thiol, CH SH, are not usually formed. 

Molecular Sieve Treatment. Molecular sieve treaters can be designed to remove H2S, organic sulfur compounds (including carbonyl sulfide), and water in one step. SoHd-bed units are utilized and regeneration occurs in the same manner as simple, soHd-bed dehydrators. 

Physica.1 Properties. Carbonyl sulfide [463-58-1] (carbon oxysulfide), COS, is a colorless gas that is odorless when pure however, it has been described as having a foul odor. Physical constants and thermodynamic properties are Hsted ia Table 1 (17,18). The vapor pressure has been fitted to an equation, and a detailed study has been made of the phase equiUbria of the carbonyl sulfide—propane system, which is important ia the purification of propane fuel (19,20). Carbonyl sulfide can be adsorbed on molecular sieves (qv) as a means for removal from propane (21). This approach has been compared to the use of various solvents and reagents (22). 

Alternative means for removal of carbonyl sulfide for gas streams iavolve hydrogenation. For example, the Beavon process for removal of sulfur compounds remaining ia Claus unit tail gases iavolves hydrolysis and hydrogenation over cobalt molybdate catalyst resulting ia the conversion of carbonyl sulfide, carbon disulfide, and other sulfur compounds to hydrogen sulfide (25). 

To effectively remove carbonyl sulfide from a gas stream, special alkaline scmbbiag Hquors are used. These contain sodium aluminate or sodium plumbite, or they are made of alkaUes with a hydrolysis catalyst based on Zn, Fe, Ni, or Cu. Diethanolamine, diglycolamine, or other alkanolamines (qv) mixed with water remove carbonyl sulfide from sour, ie, acid-gas-containing, gas streams (25,26) (see Carbon dioxide). 

Carbonyl sulfide occurs as a by-product ia the manufacture of carbon disulfide and is an impurity ia some natural gases, ia many manufactured fuel gases and refinery gases, and ia combustion products of sulfur-containing fuels (25). It tends to be concentrated ia the propane fraction ia gas fractionation an amine sweetening process is needed to remove it. 

Although the continuous-countercurrent type of operation has found limited application in the removal of gaseous pollutants from process streams (Tor example, the removal of carbon dioxide and sulfur compounds such as hydrogen sulfide and carbonyl sulfide), by far the most common type of operation presently in use is the fixed-bed adsorber. The relatively high cost of continuously transporting solid particles as required in steady-state operations makes fixed-bed adsorption an attractive, economical alternative. If intermittent or batch operation is practical, a simple one-bed system, cycling alternately between the adsorption and regeneration phases, 1 suffice. 

The Beaven process is also effective in removing small amounts of sulfur dioxide, carbonyl sulfide, and carbon disulfide that are not affected by the Claus process. These compounds are first converted to hydrogen sulfide at elevated... 

TliCNC reactions are reversible. DEA reacts with carbonyl sulfide (CUS) and carbon disulfide (CS2) to form compounds that can be regenerated in the stripping column. Therefore, COS and CS2 are removed without a loss i)f DEA. Typically, DEA systems include a carbon filter but do not include a reclaimer. 

Diisopropanolamine Systems. Diisopropanolamine (DIPA) is a secondary amine used in the Shell ADIP process to sweeten natural gas. DIPA systems are similar to MEA systems but offer the following ad an-tages carbonyl sulfide (COS) can be removed and regenerated easily and the system is generally noncorrosive and requires less heat input. 

Adip [Possibly an acronym of DIPA, di-isopropanolamine] A process for removing hydrogen sulfide, mercaptans, carbonyl sulfide, and carbon dioxide from refinery streams by extraction into an aqueous solution of di-isopropanolamine or methyl diethanolamine. Developed and licensed by the Shell Oil Company, Houston, TX. More than 320 units were operating in 1992. 

Beavon [Beavon Sulfur Removal] Also called BSR. A process for removing residual sulfur compounds from the effluent gases from the Claus process. Catalytic hydrogenation over a cobalt/molybdena catalyst converts carbonyl sulfide, carbon disulfide, and other... 

COMBISULF A process for removing sulfur compounds from the gases from combined-cycle power plants with integrated coal gasification. Carbonyl sulfide is removed by catalytic hydrolysis hydrogen sulfide is removed by selective absorbtion in aqueous MEDA and the sulfur is recovered from both processes by a modified Claus unit. Developed by Krupp Koppers and first operated in Spain in 1996. See PRENFLO. 

Katasorbon A process for removing carbonyl sulfide and other organic sulfur compounds from syngas by combined catalysis and adsorption. Offered by Lurgi. 

Malaprop A process for removing carbonyl sulfide from gas streams by scrubbing with diethylene glycolamine (DGA). 

Sulfinol A process for removing hydrogen sulfide, carbon dioxide, carbonyl sulfide, and organic sulfur compounds from natural gas by scrubbing with di-isopropanolamine dissolved in a mixture of sulfolane and water. Developed in the 1960s by Shell International Research Mij N.V, The Netherlands and Shell Development Company, Houston. In 1996, over 180 commercial units were operating or under construction. 

The manufacturing processes for liquefied petroleum gas are designed so that the majority, if not all, of the sulfur compounds are removed. The total snlfnr level is therefore considerably lower than for other petrolenm fuels, and a maximnm limit for sulfur content helps to define the prodnct more completely. The snlfnr compounds that are primarily responsible for corrosion are hydrogen snlfide, carbonyl sulfide, and sometimes, elemental sulfur. Hydrogen sulfide and mercaptans have distinctive unpleasant odors. 

The Gassman indole synthesis involves a one-pot process in which a hypohalite, a P-carbonyl sulfide derivative, and a base are added sequentially to an aniline or a substituted aniline to provide 3-thioalkoxyindoles. The sulfur can be easily removed by hydrogenolysis or Raney nickel. 

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