Process for converting waste plastics in the presence of a solvent, resulting from the conversion of used tyres

Patent metadata

Field	Value
Publication number	US-11820946-B2
Application number	US-202117208626-A
Country	US
Kind code	B2
Filing date	Mar 22, 2021
Priority date	Mar 26, 2020
Publication date	Nov 21, 2023
Grant date	Nov 21, 2023

Abstract

The invention relates to a process for converting a plastic feedstock and for converting used tyres to obtain carbon black, comprising the following steps:
a) a solid feedstock ( 100 ) based on used tyres is sent into a reaction zone ( 10 ) in the presence of a liquid solvent ( 340 ) comprising aromatic compounds to at least partly dissolve said solid feedstock and to thermally decompose said dissolved solid feedstock so as to obtain carbon black ( 160 ) and a first hydrocarbon-based liquid fraction ( 120 ); b) a molten plastic feedstock ( 200 ) is sent together with at least a portion of the first hydrocarbon-based liquid fraction ( 120 ) obtained on conclusion of step a) into a conversion zone ( 20 ) to dissolve said molten plastic feedstock ( 200 ) and to thermally decompose said dissolved plastic feedstock so as to obtain a second hydrocarbon-based liquid fraction ( 230 ).

First claim

The invention claimed is:

1. Process for converting a plastic feedstock and for converting used tyres to obtain carbon black, comprising at least the following steps:
a) a solid feedstock ( 100 ) based on used tyres is sent into a reaction zone ( 10 ) in the presence of a liquid solvent ( 340 ) comprising aromatic compounds to at least partly dissolve said solid feedstock and to thermally decompose at a temperature of less than or equal to 425° C. said at least partially dissolved solid feedstock so as to obtain at least carbon black ( 160 ) and a first hydrocarbon-based liquid fraction ( 120 );
b) a molten plastic feedstock ( 200 ) is sent together with at least a portion of the first hydrocarbon-based liquid fraction ( 120 ) obtained on conclusion of step a) into a conversion zone ( 20 ) to at least partly dissolve said molten plastic feedstock ( 200 ) and to thermally decompose at a temperature of less than or equal to 450° C. said partially dissolved plastic feedstock so as to obtain at least partly a second hydrocarbon-based liquid fraction ( 230 );
c) the first hydrocarbon-based liquid fraction ( 120 ) obtained from step a) is at least partly sent to a fractionation zone ( 30 ) to obtain at least one intermediate hydrocarbon cut ( 360 ) whose initial boiling point is between 250 and 325° C. and whose final boiling point is between 350 and 450° C., a light cut and a heavy cut; and
d) a fraction of the intermediate hydrocarbon cut ( 360 ) is at least partly sent to the reaction zone ( 10 ) of step a) as liquid solvent ( 340 ), wherein a portion of the first hydrocarbon-based liquid fraction ( 120 ) from step a is provided to step b and a portion of a first hydrocarbon-based liquid fraction ( 120 ) is provided to step c.

2. Process according to claim 1 , in which said first hydrocarbon-based liquid fraction ( 120 ) has a content of aromatic compounds of between 30% and 70% by weight relative to the total weight of said first hydrocarbon-based liquid fraction.

3. Process according to claim 1 , in which said intermediate hydrocarbon cut ( 360 ) has a content of aromatic compounds of between 30% and 70% by weight relative to the total weight of said intermediate hydrocarbon cut.

4. Process according to claim 1 , in which a portion of the second hydrocarbon-based liquid fraction ( 230 ) is sent to the fractionation zone ( 30 ).

5. Process according to claim 1 , in which a fraction of the intermediate hydrocarbon cut ( 360 ) is at least partly sent to the conversion zone ( 20 ) as additional liquid solvent ( 350 ).

6. Process according to claim 1 , in which the intermediate hydrocarbon cut ( 360 ) is at least partly sent to an aromatic compound enrichment unit ( 40 ) to obtain a stream rich in aromatic compounds ( 410 ) and a stream depleted in aromatic compounds ( 420 ), said stream rich in aromatic compounds ( 410 ) being sent into the reaction zone ( 10 ) as liquid solvent ( 340 ).

7. Process according to claim 6 , in which said stream rich in aromatic compounds ( 410 ) is at least partly sent to the conversion zone ( 20 ) as additional liquid solvent ( 350 ).

8. Process according to claim 6 , wherein said aromatic compound enrichment unit ( 40 ) is chosen from units for extraction with the solvent furfural, phenol or N-methyl-2-pyrrolidone.

9. Process according to claim 1 , in which said plastic feedstock is a mixture of plastics containing at least 90% by weight of polyolefins and of polystyrene relative to the total weight of said feedstock.

10. Process according to claim 1 , in which the first hydrocarbon-based liquid fraction ( 120 ) and/or the second hydrocarbon-based liquid fraction ( 230 ) comprises at least 40% by weight of compounds whose initial boiling point is greater than 300° C.

11. Process according to claim 1 , in which the ratio between the flow rate of the liquid solvent ( 340 ) and the flow rate of said solid feedstock ( 100 ) that are injected into the reaction zone ( 10 ) is between 1 and 10 weight/weight.

12. Process according to claim 5 , in which the ratio between the sum of the flow rates of the hydrocarbon-based liquid fraction ( 120 ) and the additional liquid solvent ( 350 ) divided by the flow rate of the molten plastic feedstock ( 200 ) is between 1 and 10 weight/weight.

13. Process according to claim 1 , in which step a) comprises the following substeps:
a1) said solid feedstock ( 100 ) and said liquid solvent ( 340 ) are sent into a first stirred reactor ( 13 ) to at least partly dissolve said solid feedstock ( 100 );
a2) said at least partly dissolved solid feedstock obtained on conclusion of step a1) is sent into a second stirred reactor ( 14 ) to thermally decompose at a temperature of less than or equal to 425° C. said solid feedstock and to obtain a liquid effluent containing carbon black particles in suspension;
a3) said liquid effluent obtained on conclusion of step a2) is cooled to a temperature of less than 150° C.;
a4) the carbon black particles are filtered off, washed and separated from the cooled liquid effluent obtained on conclusion of step a3) to obtain carbon black ( 160 ) and a first hydrocarbon-based liquid fraction ( 120 ).

14. Process according to claim 1 , in which step b) comprises the following substeps:
b1) said molten plastic feedstock ( 200 ) and at least a portion of the first hydrocarbon-based liquid fraction ( 120 ) are sent into a first stirred reactor ( 23 ) to at least partly dissolve said molten plastic feedstock;
b2) said at least partly dissolved plastic feedstock obtained on conclusion of step b1) is sent into a second stirred reactor ( 27 ) to thermally decompose at a temperature of less than or equal to 425° C. said plastic feedstock and at least partly to obtain a second hydrocarbon-based liquid fraction ( 230 ).

Assignees

• Ifp Energies Now

Inventors

• Gauthier Thierry
• Digne Romina

Classifications

• B29L2030/00

  Pneumatic or solid tyres or parts thereof {(conveyor belts B29L2031/7092; drive belts B29L2031/7094; fourdrinier belts B29L2031/733)} · CPC title

• B29B17/02

  Separating plastics from other materials · CPC title

• C10G1/10 Primary

  from rubber or rubber waste · CPC title

• B01D3/14

  Fractional distillation {or use of a fractionation or rectification column} · CPC title

• B01D11/0492

  Applications, solvents used · CPC title