Process for dechlorination of waste plastics

Patent metadata

Field	Value
Publication number	US-2024376025-A1
Application number	US-202218683198-A
Country	US
Kind code	A1
Filing date	Aug 19, 2022
Priority date	Aug 23, 2021
Publication date	Nov 14, 2024
Grant date	—

Abstract

A process involving the steps in this order of: providing a waste plastics stream (A) comprising polyvinyl chloride (PVC); (i) supplying the waste plastics stream (A) to a reactor vessel; (ii) subjecting the waste plastics in the reactor vessel to a temperature of ≥250° C. and ≤350° C., preferably of ≥275° C. and ≤325° C., preferably for a period of 5-30 minutes, under applying a vacuum, preferably of ≤35 mbar, or using an inert gas sweep, and evacuating the generated hydrogen chloride (B) from the vessel, wherein the PVC is partially dechlorinated to form a waste plastics stream (C) comprising partially unsaturated PVC; (iii) removing the waste plastics stream (C) comprising partially unsaturated PVC from the reaction vessel; and (iv) separating the partially unsaturated PVC from the waste plastics stream to form a dechlorinated waste plastics stream (D).

First claim

1 . Process for the dechlorination of waste plastics, the process involving the steps in this order of:
(i) providing a waste plastics stream (A) comprising polyvinyl chloride (PVC); (ii) supplying the waste plastics stream (A) to a reactor vessel; (iii) subjecting the waste plastics in the reactor vessel to a temperature of ≥250° C. to <350, under applying a vacuum or using an inert gas sweep, and evacuating the generated hydrogen chloride (B) from the vessel, wherein the PVC is partially dechlorinated to form a waste plastics stream (C) comprising partially unsaturated PVC; and (iv) removing the waste plastics stream (C) comprising partially unsaturated PVC from the reaction vessel.

2 . Process according to claim 1 , wherein the waste plastics stream (A) comprises ≥0.5 and ≤10.0 wt % of PVC, with regard to the total weight of the waste plastics stream.

3 . Process according to claim 1 , wherein the waste plastics are present in the reactor vessel in step (iii) in a molten state or as a slurry.

4 . Process according to claim 1 , wherein the step (ii) involves passing the waste plastics stream (A) via a melt extruder operating at a temperature of ≤250° C. to obtain a molten waste plastics stream, and supplying the molten waste plastics stream to the reactor vessel.

5 . Process according to claim 4 , wherein the molten waste plastics stream exiting the melt extruder is, prior to being supplied to the reactor vessel, further heated to a temperature of ≥250° C. and ≤300° C.

6 . Process according to claim 4 , wherein the molten waste plastics stream is mixed with a medium (E), a hydrocarbon compound or composition that is suitable as feed for use in a subsequent refinery or chemical operation.

7 . Process according to claim 1 , wherein: the process further comprises (v) separating the partially unsaturated PVC from the waste plastics stream to form a dechlorinated waste plastics stream (D); and the separation step (v) is performed by passing the waste plastics stream (C) comprising partially unsaturated PVC that is removed from the reaction vessel over a filter system in a state that the partially unsaturated PVC is present in the waste plastics stream in solid form, so that the dechlorinated waste plastics stream (D) and a solid partially unsaturated PVC stream (F) is obtained.

8 . Process according to claim 7 , wherein the filter system has an average pore size of ≤25 μm.

9 . Process according to claim 7 , wherein: the process further comprises (v) separating the partially unsaturated PVC from the waste plastics stream to form a dechlorinated waste plastics stream (D); and the step (v) is performed at a temperature of ≥200° C.

10 . Process according to claim 1 , wherein the evacuated HCl stream (B) is subjected to a caustic treatment to complex HCl with NaOH to obtain NaCl.

11 . Process according to claim 6 , wherein the evacuated HCl-containing stream (B) is, immediately upon exiting the reactor vessel, passed through a condenser to remove medium, which subsequently is returned into the reactor.

12 . Process according to claim 1 , wherein the process is a continuously operating process.

13 . Process according to claim 1 , wherein the reactor vessel is equipped with an inert gas purge.

Assignees

• Sabic Global Technologies Bv

Inventors

• Schucker Robert C
• Farmer Dustin
• Loiland Jason

Classifications

• C10G1/10 Primary

  from rubber or rubber waste · CPC title

• C01D3/04

  Chlorides · CPC title

• C01B7/035

  Preparation of hydrogen chloride from chlorides · CPC title

• B29K2027/06

  PVC, i.e. polyvinylchloride · CPC title

• B29B2017/0224

  Screens, sieves · CPC title