Co-processing of waste plastic with biomass

Patent metadata

Field	Value
Publication number	US-11225609-B2
Application number	US-202017019803-A
Country	US
Kind code	B2
Filing date	Sep 14, 2020
Priority date	Nov 1, 2019
Publication date	Jan 18, 2022
Grant date	Jan 18, 2022

Abstract

Systems and methods are provided for co-processing of plastic waste with biomass to generate gas phase product streams with improved properties. The systems and methods can include having a high temperature swing adsorption process integrated with a pyrolysis process, gasification process, or other thermal conversion process, so that CO 2 can be removed from at least a portion of the effluent. This can facilitate capture of CO 2 when using pyrolysis, gasification, or other thermal conversion to generate a hydrogen-containing stream. Additionally, the integrated system and/or method can allow for production of multiple product streams having desirable ratios of hydrogen to carbon oxides.

First claim

The invention claimed is:

1. A method for forming a plurality of synthesis gas compositions, comprising:
exposing a feedstock comprising a mixture of biomass and plastic waste to pyrolysis conditions at a temperature of 500° C. to 1200° C. to form at least a low-hydrogen-content synthesis gas stream comprising H 2 , CO, and CO 2 , the low-hydrogen-content synthesis gas stream comprising a molar ratio of H 2 to CO of 0.5 to 1.7;
exposing at least a portion of the low-hydrogen-content synthesis gas stream to an adsorbent at a first adsorbing temperature of 300° C. to 600° C. and a first adsorbing pressure of 1.0 MPa-g or more to form an H 2 -enriched stream comprising an H 2 to CO ratio of 10 or more;
combining a first portion of the H 2 -enriched stream with a first bypass portion of the low hydrogen content synthesis gas stream to form a first product synthesis gas stream comprising a first H 2 to CO ratio of 1.8 or more; and
combining a second portion of the H 2 -enriched stream with a second bypass portion of the low hydrogen content synthesis gas stream to form a second product synthesis gas stream comprising a second H 2 to CO ratio of 1.8 or more.

2. The method of claim 1 , wherein the H 2 -enriched stream comprises 5.0 mol % or less of CO, 10 mol % or less of CO 2 , or a combination thereof.

3. The method of claim 1 , wherein the pyrolysis conditions comprise gasification conditions.

4. The method of claim 1 , wherein the first product synthesis gas stream comprises an S-ratio of 1.8-2.1, or wherein the second product synthesis gas stream comprises an M-ratio of 1.9-2.2, or a combination thereof.

5. The method of claim 1 , wherein the feedstock is exposed to the pyrolysis conditions in a reactor by flowing the feedstock in a first direction within the reactor, the method further comprising regenerating the reactor by performing combustion in the reactor, the regenerating comprising flowing the combustion products within the reactor in a second direction different from the first direction.

6. The method of claim 1 , wherein the feedstock comprises 51 wt % or more of biomass relative to a combined weight of the biomass and the plastic waste.

7. The method of claim 1 , wherein the at least a portion of the low-hydrogen-content synthesis gas stream comprises 10 mol % or more of H 2 O.

8. The method of claim 1 , further comprising desorbing CO 2 from the adsorbent at a pressure of 5.0 MPa-g or less.

9. The method of claim 8 , wherein desorbing CO 2 from the adsorbent comprises exposing the adsorbent to a purge stream of H 2 O.

10. The method of claim 1 , further comprising physically processing at least a portion of the plastic waste, at least a portion of the biomass, or a combination thereof prior to exposing the feedstock to the thermal conversion conditions to form particles having a median particle size of 3.0 mm or less.

11. The method of claim 1 , wherein the feedstock further comprises at least one of a solvent and a carrier.

12. The method of claim 1 , wherein the adsorbent comprises a mixed metal oxide adsorbent.

13. The method of claim 12 , wherein the mixed metal oxide adsorbent comprises an alkali metal carbonate, an alkaline earth metal carbonate, or a combination thereof.

14. The method of claim 12 , wherein the mixed metal oxide adsorbent comprises an alkaline earth oxide, a transition metal oxide, or a combination thereof.

15. The method of claim 1 , wherein exposing at least a portion of the low-hydrogen-content synthesis gas stream to an adsorbent comprises performing a water gas shift reaction on the at least a portion of the low-hydrogen-content synthesis gas stream.

16. The method of claim 15 , wherein at least a portion of the water for performing the water gas shift reaction comprises water desorbed from the adsorbent.

17. The method of claim 1 , further comprising:
exposing a second feedstock comprising a mixture of biomass and plastic waste to pyrolysis conditions at a temperature of 500° C. to 1200° C. to form at least a second low hydrogen content synthesis gas stream comprising H 2 , CO, and CO 2 , the second low-hydrogen-content synthesis gas stream comprising i) a second hydrogen content that differs from a hydrogen content of the low-hydrogen-content synthesis gas stream by 10 vol % or more, ii) a second CO 2 content that differs from a CO 2 content of the low hydrogen content synthesis gas stream by 10 vol % or more, or iii) a combination of i) and ii);
exposing at least a portion of the second low-hydrogen-content synthesis gas stream to an adsorbent at a second adsorbing temperature of 300° C. to 600° C. and a second adsorbing pressure of 1.0 MPa-g or more to form a second H 2 -enriched stream comprising an H 2 to CO ratio of 10 or more, the second adsorbing temperature differing from the first temperature by 10° C. or less and the second adsorbing pressure differing from the first pressure by 100 kPa or less;
combining a first portion of the second H 2 -enriched stream with a third bypass portion of the low hydrogen content synthesis gas stream to form a third product synthesis gas stream comprising a first H 2 to CO ratio of 1.8 or more; and
combining a second portion of the H 2 -enriched stream with a fourth bypass portion of the low hydrogen content synthesis gas stream to form a fourth product synthesis gas stream comprising a second H 2 to CO ratio of 1.8 or more.

18. The method of claim 1 , wherein exposing a feedstock comprising a mixture of biomass and plastic waste to pyrolysis conditions comprising forming a pyrolysis effluent comprising 10 vol % or more hydrocarbons, the method further comprising separating the pyrolysis effluent to form the low-hydrogen-content synthesis gas stream.

19. The method of claim 18 , wherein separating the pyrolysis effluent to form the low-hydrogen-content synthesis gas stream comprises forming a low-hydrogen-content synthesis gas stream with an H 2 O content of 10 vol % or less.

20. The method of claim 1 , wherein the low-hydrogen-content synthesis gas is formed and exposed to the adsorbent without exposing the low-hydrogen-content synthesis gas to a temperature of 100° C. or less.

Assignees

• Exxonmobil Res & Eng Co

Inventors

• Sundaram Narasimhan

Classifications

• C10K3/06

  by mixing with gases · CPC title

• C10B53/07 Primary

  {of solid raw materials consisting} of synthetic polymeric materials, e.g. tyres (recovery or working-up of waste materials of organic macromolecular compounds or compositions based thereon by dry-heat treatment for obtaining partially depolymerised materials C08J11/10; production of liquid hydrocarbon mixtures from rubber or rubber waste C10G1/10) · CPC title

• C10J2300/0916

  Biomass · CPC title

• C10J2300/1665

  to alcohols, e.g. methanol or ethanol · CPC title

• B01D53/02

  by adsorption, e.g. preparative gas chromatography {(solid sorbent compositions B01J20/00, preparation of inorganic compounds or elements C01)} · CPC title