Ionic liquid-based hydrogen sulfide and mercaptan scavengers

A method for removing a sulfur compound from a hydrocarbon stream containing the sulfur compound, the method comprising:

• contacting the hydrocarbon stream with an amount of a basic ionic liquid effective to react with the sulfur compound to form at least one reaction product in a treated hydrocarbon stream;
• where:
• the basic ionic liquid comprises:
• a quaternary ammonium compound having the formula R4N+ X− or X− R3N+R′N+R3 X−, where R is independently an alkyl group, an alkylbenzyl group, a hydroxyalkyl group, or a hydroxyalkylbenzyl group, and R is straight or branched and has 1 to 22 carbon atoms, R′ is a straight or branched alkylene or oxyalkylene having 1 to 10 carbon atoms, and where X− is selected from the group consisting of hydroxide, carbonate, alkylcarbonate, bicarbonate or alkoxide, where the alkyl group of the alkylcarbonate or alkoxide, if present, is straight or branched and has 1 to 8 carbon atoms;
• and
• a liquid selected from the group consisting of water, a monohydric or polyhydric alcohol having 1 to 8 carbon atoms, and an aromatic solvent;
• where hydrocarbons in the hydrocarbon stream range from C1-C12.

A method for removing a sulfur compound selected from the group consisting of hydrogen sulfide thiophenes, disulfides, thioethers, mercaptans, and combinations thereof from a hydrocarbon stream containing the sulfur compound, the method comprising:

• contacting the hydrocarbon stream with an amount of a basic ionic liquid effective to react with the sulfur compound to form at least one reaction product in a treated hydrocarbon stream;
• where:
• the basic ionic liquid comprises a quaternary ammonium compound having the formula R4N+ X− or X− R3N+R′N+R3 X−, where R is independently an alkyl group, an alkylbenzyl group, a hydroxyalkyl group, or a hydroxyalkylbenzyl group, and R is straight or branched and has 1 to 22 carbon atoms, R′ is a straight or branched alkylene or oxyalkylene having 1 to 10 carbon atoms, and where X− is selected from the group consisting of hydroxide, carbonate, alkylcarbonate, bicarbonate or alkoxide, where the alkyl group of the alkylcarbonate or alkoxide, if present, is straight or branched and has 1 to 8 carbon atoms;
• contacting the hydrocarbon stream with the basic ionic liquid is conducted by a method selected from the group consisting of:
• as an extraction by passing the hydrocarbon stream through the basic ionic liquid in a contact tower;
• and
• contacting the hydrocarbon stream with the basic ionic liquid is conducted by adding the basic ionic liquid to the hydrocarbon stream.