Method for reducing the level of elemental sulfur and total sulfur in hydrocarbon streams

Abstract

A method for reducing the level of elemental sulfur from sulfur-containing hydrocarbon streams as well as reducing the level of total sulfur in such streams. Preferred hydrocarbon streams include fuel streams such as naphtha streams that are transported through a pipeline. The sulfur-containing hydrocarbon stream is contacted with a mixture of water, a caustic, at least one metal sulfide, and an aromatic mercaptan. This results in an aqueous phase and a hydrocarbon phase containing reduced levels of both elemental sulfur and total sulfur.

What is claimed is:  
     
         1 . A method for reducing both the level of elemental sulfur and total sulfur of a hydrocarbon stream containing same, which method comprises: a) mixing with said stream, water, a caustic, at least one metal sulfide, and at least one aromatic mercaptan, thereby resulting in a hydrocarbon phase and an aqueous phase, wherein said mixture is used in an effective amount and under effective conditions so that the elemental sulfur reacts with said at least one metal sulfide to form the corresponding metal polysulfide that is soluble in the aqueous phase; and b) separating said aqueous phase containing said metal polysulfide component, and said hydrocarbon phase that is substantially reduced in both elemental sulfur and total sulfur.  
     
     
         2 . The method of  claim 1  wherein the hydrocarbon stream is a naphtha boiling range stream.  
     
     
         3 . The method of  claim 1  wherein the caustic is represented by the formula MOH where M is selected from the group consisting of lithium, sodium, potassium, NH 4 , and mixtures thereof.  
     
     
         4 . The method of  claim 3  wherein the caustic is used in the range of about 0.01 to 20 molar.  
     
     
         5 . The method of  claim 1  wherein the sulfide is of a metal selected from Groups 1a and 2a of the Periodic Table of the Elements.  
     
     
         6 . The method of  claim 5  wherein the sulfide is selected from the group consisting of Na 2 S, K 2 S, Li 2 S, NaHS, (NH 4 ) 2 S, and mixtures thereof.  
     
     
         7 . The method of  claim 5  wherein the sulfide is used in range of about 0.1 wt. % to about 5 wt. %.  
     
     
         8 . The method of  claim 1  wherein the aromatic mercaptan is selected from the group consisting of thiophenol, ethyl thiophenol, methyoxythiophenol, dimethylthiophenol, naphtalenethiols, phenyl-di-mercapatan, and thiocresol.  
     
     
         9 . The method of  claim 7  wherein the aromatic mercaptan is present in a range from about 1 to about 1000 wppm.  
     
     
         10 . The method of  claim 1  wherein the aromatic mercaptan is added to the hydrocarbon stream.  
     
     
         11 . The method of 1 wherein the aromatic mercaptan is added to the aqueous phase.  
     
     
         12 . The method of  claim 1  wherein the aqueous phase is from about 0.05 to about 10 times the volume of the hydrocarbon phase.  
     
     
         13 . The method of  claim 12  wherein the aqueous phase is from about 0.1 to about 10 times the volume of the hydrocarbon phase.  
     
     
         14 . A method for reducing both the level of elemental sulfur and total sulfur of a hydrocarbon stream containing same, which method comprises: a) mixing with said stream, water, a caustic represented by the formula MOH where M is selected from the group consisting of lithium, sodium, potassium, NH 4 , and mixtures thereof, at least one metal sulfide of a metal selected from Groups 1a and 2a of the Periodic Table of the Elements, and at least one aromatic mercaptan, thereby resulting in a hydrocarbon phase and an aqueous phase, wherein said mixture is used in an effective amount and under effective conditions so that the elemental sulfur reacts with said at least one metal sulfide to form the corresponding metal polysulfide that is soluble in the aqueous phase; and b) separating said aqueous phase containing said metal polysulfide component, and said hydrocarbon phase that is substantially reduced in both elemental sulfur and total sulfur.  
     
     
         15 . The method of  claim 14  wherein the hydrocarbon stream is a naphtha boiling range stream.  
     
     
         16 . The method of  claim 14  wherein the caustic is used in the range of about 0.01 to 20 molar.  
     
     
         17 . The method of  claim 14  wherein the sulfide is selected from the group consisting of Na 2 S, K 2 S, Li 2 S, NaHS, (NH 4 ) 2 S, and mixtures thereof.  
     
     
         18 . The method of  claim 17  wherein the sulfide is used in range of about 0.1 wt. % to about 5 wt. %.  
     
     
         19 . The method of  claim 14  wherein the aromatic mercaptan is selected from the group consisting of thiophenol, ethyl thiophenol, methyoxythiophenol, dimethylthiophenol, naphtalenethiols, phenyl-di-mercapatan, and thiocresol.  
     
     
         20 . The method of  claim 19  wherein the aromatic mercaptan is present in a range from about 1 to about 1000 wppm.  
     
     
         21 . The method of  claim 14  wherein the aromatic mercaptan is added to the hydrocarbon stream.  
     
     
         22 . The method of 14 wherein the aromatic mercaptan is added to the aqueous phase.  
     
     
         23 . The method of  claim 14  wherein the aqueous phase is from about 0.05 to about 10 times the volume of the hydrocarbon phase.  
     
     
         24 . The method of  claim 23  wherein the aqueous phase is from about 0.1 to about 10 times the volume of the hydrocarbon phase.