Process and apparatus for preparing purified styrene composition from styrene containing feedstock

Patent metadata

Field	Value
Publication number	US-11891358-B2
Application number	US-202117916554-A
Country	US
Kind code	B2
Filing date	May 7, 2021
Priority date	May 8, 2020
Publication date	Feb 6, 2024
Grant date	Feb 6, 2024

Abstract

A method for preparing a purified styrene composition with a styrene yield of at least 80%. The method comprises providing a crude composition containing styrene, and subjecting the crude composition to at least one crystallization step. The at least one crystallization step comprises at least one static crystallization stage and at least one dynamic crystallization stage.

First claim

The invention claimed is:

1. A method for preparing a purified styrene composition with a styrene yield of at least 80%, the method comprising:
providing a crude composition containing styrene; and
subjecting the crude composition to at least one crystallization step to produce the purified styrene composition,
the at least one crystallization step comprising at least one static crystallization stage and at least one dynamic crystallization stage.

2. The method of claim 1 , wherein the crude composition contains one or more impurities selected from the group consisting of: color inducing species, sulfur species, meta-xylenes, ortho-xylenes, ethylbenzene, phenylacetylene, cumene, n-propylbenzene, alpha-methylstyrene, ethyltoluene, organochlorinated, organo-nitrogenated species and arbitrary mixtures of two or more of the aforementioned impurities.

3. The method of claim 1 , wherein the at least one dynamic crystallization stage is a falling film crystallization stage or a suspension crystallization stage.

4. The method of claim 1 , wherein the at least one crystallization step comprises one to ten static crystallization stages and one to ten dynamic crystallization stages.

5. The method of claim 1 , wherein:
providing the crude composition comprises subjecting a feed composition to at least one of: one or more distillation steps and one or more extractive distillation steps, and
the crude composition is obtained as a head stream, as a side stream or as a bottom stream of one of the at least one of: one or more distillation steps and one or more extractive distillation steps.

6. The method of claim 1 , wherein the crude composition derives from a pygas, the crude composition being prepared by:
distilling a pygas feed composition so as to obtain a C8-fraction and subjecting the C8-fraction to an extractive distillation in which the C8-fraction is treated with a polar solvent so as to obtain a styrene containing fraction as an overhead stream, as a side stream or as a bottom stream, which is used as the crude composition or which is processed into the crude composition, or
distilling a pygas feed composition so as to obtain a C8-fraction, feeding the C8-fraction into a hydrogenation reactor so as to obtain a hydrogenated gas, subjecting the hydrogenated gas to an extractive distillation in which the hydrogenated gas is treated with a polar solvent so as to obtain a styrene containing fraction as an overhead stream, as a side stream or as a bottom stream, which is used as the crude composition or which is processed into the crude composition.

7. The method according to claim 1 , wherein the crude composition derives from an ethylbenzene and styrene containing stream produced in an ethyl-benzene/styrene monomer (EBSM) process or derives from a styrene containing stream produced by polystyrene pyrolysis.

8. The method of claim 1 , wherein the purified styrene composition has a styrene content of at least 99.00% by weight.

9. The method of claim 1 , wherein the purified styrene composition has a color of maximum 15 as defined by Pt—Co scale as per ASTM D5386.

10. The method of claim 1 , wherein the purified styrene composition comprises at least one of:
less than 5 ppmw of total elemental sulfur as contained in mercaptans, disulfides and thiophenes,
less than 20 ppmw of oxygenates,
less than 40 ppmw of impurities selected from the group consisting of: phenylacetylene, mixed xylenes, ethylbenzene, cumene, ethyl-toluene, n-propylbenzene, and alpha-methylstyrene,
a polymer content of less than 10 ppmw, and
a total organic chlorine content of less than 2 ppmw.

11. The method of claim 1 , wherein:
in the at least one crystallization step, a purified styrene composition and a styrene depleted mother liquor are obtained, and
at most 50% by volume of the styrene depleted mother liquor is recycled to an optional distillation step.

Assignees

• Sulzer Management Ag

Inventors

• Khandelwal Rahul
• Gentry Joseph C
• Wytcherley Randi
• Anderson Kimberly
• Naulita-Ellis Meta
• Pudack Claudia
• Rioual Celine
• Kirschner Christoph
• Slimp B Bryant
• Stepanski Manfred
• Temmel Erik

Classifications

• C07C7/14 Primary

  by crystallisation; Purification or separation of the crystals · CPC title

• B01D3/143

  by two or more of a fractionation, separation or rectification step · CPC title

• B01D3/40

  Extractive distillation · CPC title

• B01D9/0013

  by indirect heat exchange · CPC title

• B01D9/0031

  by heating (B01D9/0022, B01D9/0027 take precedence) · CPC title