Residual stream upgrading in a propylene oxide-styrene monomer process
View Patent ↗In the co-production of propylene oxide and styrene monomer, there is produced a sodium-containing heavy residue stream previously suitable only as a low grade fuel. In accordance with the invention, the heavy residue stream is mixed with a hydrocarbon and an aqueous acid, and the resulting mixture is separated into an aqueous sodium salt-containing slurry phase and an organic phase reduced in sodium.
1. A process for removing sodium from a heavy residue formed in the co-production of propylene oxide and styrene, said process comprising adding a hydrocarbon comprising hexane and an aqueous acid to the heavy residue, and separating the resulting mixture into an aqueous sodium salt-containing phase and an organic phase having reduced sodium content.
2. The process of claim 1 wherein the hydrocarbon comprises ethyl benzene.
3. The process of claim 1 wherein the hydrocarbon is used in an amount between 10 and 40 percent by weight, based on the total amount of heavy residue.
4. The process of claim 1 wherein the aqueous acid comprises an acid selected from the group consisting of sulfuric acid, phosphoric acid, oxalic acid, and mixtures thereof.
5. The process of claim 4 wherein the acid is sulfuric acid.
6. The process of claim 1 wherein the phase separation is conducted at a temperature in the range of 25° C. to 70° C.
7. The process of claim 1 wherein at least a portion of the organic phase is cracked to form styrene monomer.
8. The process of claim 7 wherein the organic phase is subjected to wiped film evaporation to produce a volatile stream, and the volatile stream is cracked to form styrene monomer.
9. The process of claim 1 wherein the organic phase is distilled to produce an overhead stream comprising the hydrocarbon.
10. The process of claim 9 wherein at least a portion of the overhead stream is cracked to form styrene monomer.
11. The process of claim 10 wherein the overhead stream is subjected to wiped film evaporation to produce a volatile stream, and the volatile stream is cracked to form styrene monomer.