Formulations and methods to remove non-acidic sulfur compounds from gas streams
Non-acidic sulfur compounds can be extracted from a gas stream by contacting the gas stream with a carbonate solvent that contains at least one organic carbonate in an amount that is effective to solvate at least a portion of the non-acidic sulfur compounds. The gas steam can then be separated from the carbonate solvent that contains the non-acidic sulfur compounds. The carbonate solvent may optionally include a co-solvent and/or a mercaptan scavenger.
1 . A carbonate solvent for removing non-acidic sulfur compounds from a gas stream, the carbonate solvent comprising:
at least one organic carbonate;
a mercaptan scavenger, wherein the mercaptan scavenger is an oxazolidine; and
a co-solvent selected from the group consisting of caprolactam, valerolactam, azetidinone, aza-2-cyclooctanone, aminododecanolactam, and combinations thereof.
2 . The carbonate solvent of claim 1 , wherein the organic carbonate is selected from the group consisting of ethylene carbonate, propylene carbonate, glycerol carbonate, dimethyl carbonate, diethyl carbonate, styrene carbonate, and combinations thereof.
3 . The carbonate solvent of claim 1 , wherein the organic carbonate comprises propylene carbonate.
4 . A method for extracting non-acidic sulfur compounds from a gas stream, the method comprising the steps of:
obtaining a carbonate solvent, where the carbonate solvent comprises at least one organic carbonate;
contacting the gas stream with an amount of the carbonate solvent that is effective to solvate at least a portion of the non-acidic sulfur compounds from the gas stream; separating the gas stream from the carbonate solvent containing the non-acidic sulfur compounds;
removing the at least a portion of the non-acidic sulfur compounds from the carbonate solvent to obtain a regenerated carbonate solvent; and
treating a subsequent volume of gas stream having non-acidic sulfur compounds with the regenerated carbonate solvent.
5 . The method of claim 4 , wherein the at least one organic carbonate is selected from the group consisting of ethylene carbonate, propylene carbonate, glycerol carbonate, dimethyl carbonate, diethyl carbonate, styrene carbonate, and combinations thereof.
6 . The method of claim 4 , wherein the non-acidic sulfur compounds are selected from the group consisting of thiols, sulfides, disulfides, sulfoxides, thiolanes, thiophenes, benzothiophenes, dibenzothiophenes, benzonaphthothiophenes, and combinations thereof.
7 . The method of claim 4 , wherein the non-acidic sulfur compounds comprise dimethyl sulfide.
8 . The method of claim 4 , wherein the non-acidic sulfur compounds are present in a concentration of between about 20 ppm and about 10,000 ppm in the gas stream before the step of contacting the gas stream with the amount of the carbonate solvent.
9 . The method of claim 4 , wherein the non-acidic sulfur compounds are present in a concentration of about 100 ppm in the gas stream before the step of contacting the gas stream with the amount of the carbonate solvent.
10 . The method of claim 4 , wherein the step of obtaining the carbonate solvent further comprises the step of mixing the at least one organic carbonate with at least one co-solvent selected from the group consisting of caprolactam, valerolactam, azetidinone, aza-2-cyclooctanone, aminododecanolactam, and combinations thereof.
11 . The method of claim 4 , wherein the step of contacting the gas stream further comprises bubbling the gas stream through the carbonate solvent.
12 . The method of claim 4 , wherein the step of contacting the gas stream further comprises the step of introducing the gas stream to the carbonate solvent in a contact tower.
13 . The method of claim 4 , wherein the step of contacting the gas stream is performed at a temperature between −10° C. and 60° C.
14 . A method for extracting non-acidic sulfur compounds from a gas stream, the method comprising the steps of:
obtaining a carbonate solvent comprising at least one organic carbonate;
bubbling the gas stream through a first amount of the carbonate solvent that is effective to solvate at least a first portion of the non-acidic sulfur compounds from the gas stream, wherein the non-acidic sulfur compounds comprise dimethyl sulfide;
bubbling the gas stream through a second amount of the carbonate solvent that is effective to solvate a second portion of the non-acidic sulfur compounds from the gas stream;
separating the gas stream from the carbonate solvent containing the non-acidic sulfur compounds; and
removing the first portion and the second portion of the non-acidic sulfur compounds from the carbonate solvent.
15 . The method of claim 14 where the at least one organic carbonate is selected from the group consisting of ethylene carbonate, propylene carbonate, glycerol carbonate, dimethyl carbonate, diethyl carbonate, styrene carbonate, and combinations thereof.
16 . The method of claim 4 , wherein the step of removing the at least a portion of the non-acidic sulfur compounds from the carbonate solvent to obtain the regenerated carbonate solvent comprises regenerating the carbonate solvent through electrolysis.
17 . The method of claim 4 , wherein the step of removing the at least a portion of the non-acidic sulfur compounds from the carbonate solvent to obtain the regenerated carbonate solvent comprises filtration of the carbonate solvent through a solid activated media selected from the group consisting of activated carbon and silica gel.
18 . The method of claim 14 , wherein the gas stream is selected from the group consisting of syngas, propane, liquefied propane gas, and flue gas.