Method for the degrading of synthetic polymers and device for carrying out said method

• US 10,494,572 B2
• Filed: 03/27/2014
• Issued: 12/03/2019
• Est. Priority Date: 04/04/2013
• Status: Active Grant

• Current Assignee: Achim Methling Joesef Ranftl Gbr
• Original Assignee: Achim Methling Joesef Ranftl Gbr
• Inventors: Methling, Achim
• Primary Examiner(s): Louie, Philip Y
• Application Number:
  US14/782,489
• Publication Number:
  US 20160040074A1
• Time in Patent Office: 2,077 Days
• Field of Search: 4221841, 422198, 422649
• CPC Class Codes: B01J 19/0013 Controlling the temperature of the process
• CPC Class Codes: B01J 19/1862 placed in series
• CPC Class Codes: B01J 2219/00006 Large-scale industrial plants
• CPC Class Codes: B01J 2219/00063 of the reactants
• CPC Class Codes: B01J 2219/00087 with heat exchange elements outside the reactor
• CPC Class Codes: B01J 2219/00159 controlling multiple zones along the direction of flow, e.g. pre-heating and after-cooling
• CPC Class Codes: B01J 2219/00162 controlling the pressure
• CPC Class Codes: B01J 2219/00166 controlling the residence time inside the reactor vessel
• CPC Class Codes: B01J 2219/00168 controlling the viscosity
• CPC Class Codes: B01J 2219/00184 controlling the weight of reactants in the reactor vessel
• CPC Class Codes: B01J 2219/24 Stationary reactors without moving elements inside
• CPC Class Codes: C07C 4/22 by depolymerisation to the original monomer, e.g. dicyclopentadiene to cyclopentadiene
• CPC Class Codes: C08J 11/12 by dry-heat treatment only
• CPC Class Codes: C08J 2323/02 not modified by chemical after treatment
• CPC Class Codes: C08J 2323/08 Copolymers of ethene C08J2323/16 takes precedence
• CPC Class Codes: C08J 2323/10 Homopolymers or copolymers of propene
• CPC Class Codes: C10G 1/002 in combination with oil conversion- or refining processes
• CPC Class Codes: C10G 1/10 from rubber or rubber waste
• CPC Class Codes: Y02W 30/62 Plastics recycling; Rubber recycling

Abstract

A method for breaking down synthetic polymers, in particular polyolefins, is provided. In addition a system for carrying out said method and a product according to said method is provided.

Claims

1. A method for breaking down polyolefins, comprising the steps of:

a) producing a polymer melt of polyolefins;

b) purifying the polymer melt by passing the polymer melt through at least one melt filter;

c) transferring the purified polymer melt into at least one first reactor, wherein the purified polymer melt enters into a lower region (sump region) of the at least one first reactor at a temperature range of 220°

C. to 300°

C. and is conducted from the lower region (sump region) to an upper region (head region) of the at least one first reactor in a temperature gradient with heating to temperatures in a range of 330°

C. to 360°

C. such that a laminar melt flow is generated, wherein the polyolefins in the purified melt are cleaved into oligomers;

d) transferring the oligomers formed in the at least one first reactor to at least one second reactor, wherein the oligomers introduced into the at least one second reactor have a temperature in the range of 330°

C. to 360°

C., and the oligomers are conducted in a temperature gradient in the at least one second reactor from a lower region (sump region) of the at least one second reactor to an upper region (head region) of the at least one second reactor with heating to 380°

C. to 450°

C., wherein the oligomers in the at least one second reactor are broken down to C3-C22 hydrocarbons in the presence of at least one clay mineral as a depolymerization catalyst, wherein the at least one first reactor and the at least one second reactor comprise a plurality of axial heating zones configured to generate the temperature gradient in the at least one first reactor and the temperature gradient in the at least one second reactor by stepwise heating;

e) removing the C3-C22 hydrocarbons that are formed in the at least one second reactor to at least one precondenser, wherein the C3-C22 hydrocarbons exiting from the at least one second reactor are cooled in the at least one precondenser; and

f) introducing the C3-C22 hydrocarbons that are cooled in the at least one precondenser into at least one main condenser, wherein the C3-C22 hydrocarbons exiting from the at least one precondenser are liquefied in the at least one main condenser.

2. The method as claimed in claim 1, wherein the polyolefins comprise a mixture of polyethylene and polypropylene.

3. The method as claimed in claim 1, wherein the polyolefins are melted in at least one extruder at temperatures of up to 300°

C.

4. The method as claimed in claim 3, wherein a viscosity of the polymer melt at an exit of the at least one extruder is 1.0·

10⁶ to 2·

10⁶ mPas (300°

C.).

5. The method as claimed in claim 1, wherein residual traces of impurities are removed from the polymer melt in the at least one melt filter.

6. The method as claimed in claim 1, wherein the purified polymer melt exiting from the at least one melt filter is introduced by at least one melt pump into the lower region (sump region) of the at least one first reactor, wherein the purified polymer melt, on entry into the at least one first reactor, has a viscosity from 1.0·

10⁶ to 2·

10⁶ mPas (300°

C.).

7. The method as claimed in claim 1, wherein the polyolefins have a molecular weight of greater than 10⁵ kg/mol, and wherein the oligomers have a molecular weight between 10² and 10⁴ kg/mol in the at least one first reactor.

8. The method as claimed in claim 1, wherein the oligomers leaving the upper region (head region) of the at least one first reactor have a viscosity between 500 and 1000 mPas (350°

C.).

9. The method as claimed in claim 1, wherein the oligomers formed in the at least one first reactor are removed from the upper region (head region) of the at least one first reactor and introduced by at least one melt pump into the at least one second reactor.

10. The method as claimed in claim 1, wherein the oligomers leaving the at least one first reactor are mixed with the at least one clay mineral before they are introduced into the at least one second reactor.

11. The method as claimed in claim 1, wherein the at least one clay mineral comprises a layer silicate.

12. The method as claimed in claim 1, wherein the C3-C22 hydrocarbons are gaseous hydrocarbons.

13. The method as claimed in claim 1, wherein the C3-C22 hydrocarbons formed at the upper region (head region) of the at least one second reactor have a viscosity between 50 and 300 mPas (410°

C.).