Controlled catalytic oxidation of MEROX process by-products in integrated refinery process
An integrated controlled catalytic oxidation process converts low value disulfide oil (DSO) compounds produced as a by-product of a generalized mercaptan oxidation (MEROX) process into oxidized DSO (ODSO) compounds including sulfoxides, sulfones, sulfonates and sulfinates that are completely or partially water soluble and which have utility, e.g., as lubricity additives in diesel fuel and as a solvent in aromatic solvent separation processes.
1. A process for treating a mercaptan-free hydrocarbon stream comprising disulfide oil compounds derived from a refinery process employed in removing mercaptans from a hydrocarbon stream containing mercaptans, the process comprising:
subjecting the mercaptan-free hydrocarbon stream recovered from the refinery process that comprises the disulfide oil (DSO) compounds to controlled catalytic oxidation in a further refinery process by contacting the disulfide oil compounds in the presence of at least one catalyst with a predetermined molar concentration of at least one oxidant and an organic acid transfer agent to produce an oxidation effluent stream comprising oxidized disulfide oils (ODSO) and waste water;
separating the oxidation effluent stream into a water insoluble oxidized disulfide oil stream and a waste water stream; and
recovering the water insoluble oxidized disulfide oil.
2. The process of claim 1 in which the waste water stream comprises a major proportion of water soluble ODSO compounds and a minor proportion of water insoluble ODSO compounds.
3. The process of claim 2 in which the water soluble ODSO compounds in the waste water stream are separated and recovered.
4. The process of claim 1 in which the ODSO compounds contain up to six oxygen atoms.
5. The process of claim 1 in which the molar ratio of the oxidant to sulfur atoms is predetermined to control the proportion of water soluble and water insoluble ODSO compounds produced in the reaction.
6. The process of claim 1 in which the at least one oxidant is a gas phase oxidant selected from the group consisting of air, oxygen, oxides of nitrogen, ozone, and their combinations.
7. The process of claim 1 in which the oxidant is selected from the group consisting of one or more organic hydroperoxides, organic peroxides, and a combination of one or more organic hydroperoxides and organic peroxides.
8. The process of claim 1 in which the oxidant is a liquid phase peroxide selected from the group consisting of alkyl hydroperoxides, aryl hydroperoxides, dialkyl peroxides, diaryl peroxides, peresters and hydrogen peroxide.
9. The process of claim 8 in which the perester has the general formula R 1 C═O—O—O—R 2 , wherein R 1 and R 2 are the same or different alkyl or aryl groups.
10. The process of claim 1 in which the oxidant is selected from the group of liquid oxidants consisting of one or more organic hydroperoxides, organic peroxides, and a combination of one or more organic hydroperoxides and organic peroxides, and one or more gas phase oxidants selected from the group consisting of one or more of air, oxygen, oxides of nitrogen and ozone.
11. The process of claim 1 in which the DSO oxidation catalyst is a transition metal catalyst.
12. The process of claim 11 in which the transition metal catalyst contains an active species selected from the group consisting of Mo (VI), W (VI), V (V), Ti (IV), and combinations comprising at least one of the foregoing active species.
13. The process of claim 1 in which the oxidation catalyst is sodium tungstate.
14. The process of claim 12 in which the transition metal catalyst exhibits Lewis acid activity.
15. The process of claim 11 in which the oxidation potential of the transition metal catalyst is less than that of the oxidant.
16. The process of claim 1 in which the mercaptan-free hydrocarbon stream comprises a minor proportion of sulfides and a major proportion of disulfide oils.
17. The process of claim 1 in which the molar ratio of the oxidant to sulfur atoms is from 1:1 to 50:1.
18. The process of claim 1 in which the mercaptan-free hydrocarbon stream contains sulfides and disulfides, and the molar ratio of the oxidant to sulfur atoms is from 1:1 to 1:50.
19. The process of claim 1 in which the mercaptan-free hydrocarbon stream contains sulfides and disulfide oils, and the molar ratio of the oxidant to sulfur atoms is from 1.8:1 to 2.9:1.
20. The process of claim 1 in which the molar ratio of the catalyst to the disulfide oil in the oxidation step is from 0.0005 to 0.02.
21. The process of claim 1 in which the catalyst present in the disulfide oil oxidation step is from 0.15 weight % to 5.7 weight % based on the mass flow rate of the sulfides/disulfide oils mixture.