Method for upgrading plastic waste through enzymatic degradation and light reforming

Abstract

The present invention provides a method for upgrading plastic waste comprising: (i) contacting plastic from the plastic waste with an enzyme to degrade the plastic, thereby providing a composition comprising monomers and / or oligomers and / or derivatives thereof of the plastic; and (ii) photoreforming the composition to produce a product mixture comprising hydrogen and oxidation products of the monomers and / or oligomers and / or derivatives thereof.

Description

[0001] introduction

[0002] The present invention relates to the field of upcycling plastic waste into H2 and chemicals such as solar fuels. Specifically, the present invention relates to a method for upcycling plastic waste using enzymatic degradation and photoreforming. A system for upcycling plastic waste is also described.

[0003] Acknowledgements

[0004] The project leading to the present application has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (grant agreement no. 695669 - PicoCB and 966581 - SolReGen). Background Art

[0005] Plastic waste is a growing concern as an environmental pollutant. Millions of tons of synthetic plastics are produced globally each year, yet only 12% is recycled. This places significant pressure on landfills and represents a significant loss of chemical resources. Plastic waste also includes micro- and nanoplastics that accumulate in soil and marine biota. These plastics are particularly challenging to recycle due to their low concentrations and small size.

[0006] Numerous methods are currently under investigation for recycling plastics. For example, Uekert et al., J. Am. Chem. Soc. 141, 15201-15210 (2019) and Bhattacharjee et al., Nat Synth (2023), DOI:10.1038 / s44160-022-00196-0 have demonstrated that poly(ethylene terephthalate)) (PET) and poly(lactic acid) (PLA) can be photoreformed under alkaline aqueous conditions to produce H2 fuel and a variety of organic chemicals.

[0007] While these reports demonstrate the potential for waste plastic reduction and fuel generation, the main drawbacks of the aforementioned photoreforming technologies are the harsh pretreatment conditions required for plastic depolymerization (corrosive alkaline media: pH > 13; ~40–80°C), low conversion rates, and CO2 release during photoreforming due to excessive oxidation. These factors may hinder the current scale-up and commercialization of photoreforming technologies. Summary of the Invention

[0008] Overall, the present invention proposes a novel method for upcycling plastic waste by combining enzymatic treatment and photoreforming. Specifically, it has been discovered that enzymatic degradation of plastic waste can be used, followed by photoreforming of the degraded composition to produce a mixture of useful products. Advantageously, compared to prior art methods, the present method can be performed under mild conditions (i.e., temperature and pH), which facilitates scalability.

[0009] Thus, in a first aspect of the present invention there is provided a method for upcycling plastic waste comprising:

[0010] (i) contacting plastic from the plastic waste with an enzyme to degrade the plastic, thereby providing a composition comprising monomers and / or oligomers and / or derivatives thereof of the plastic; and

[0011] (ii) photoreforming the composition to produce a product mixture comprising hydrogen and oxidation products of the monomers and / or oligomers and / or derivatives thereof.

[0012] Advantageously, the method allows valuable products, including hydrogen, to be produced directly from waste plastics. The method surprisingly demonstrates high hydrogen yields compared to prior art methods. Without wishing to be bound by theory, it is believed that this results from enzymatic degradation, thereby providing a large amount of oxidizable monomers and / or oligomers and / or derivatives thereof that are effectively oxidized during photoreforming. Furthermore, the method has been shown to be effective for nanoplastics at very low concentrations. Therefore, it can allow finely distributed waste to be converted into valuable products.

[0013] Advantageously, the process can be operated under mild temperature and pH conditions, thus avoiding the need for harsh alkaline conditions employed in prior art methods. This can overcome the drawbacks associated with scaling up prior art methods for commercial use. It can also offer benefits in terms of operational safety and efficiency in upcycling plastic waste.

[0014] Advantageously, the use of enzymes also allows for high selectivity. For example, enzymes can be tuned for the degradation of specific plastics, or can be used to degrade plastics in solutions containing other components.

[0015] Advantageously, it has also been demonstrated that the method can be performed in a single reactor. This can improve operational efficiency compared to prior art methods. Surprisingly, these biological and photocatalytic reactions are compatible and can occur simultaneously.

[0016] Another benefit of the process described herein is that it allows for the simultaneous reduction of CO 2 . This can alleviate the CO 2 release problems described with respect to the prior art and can allow for the production of an H 2 / CO mixture that can be used for syngas, a highly desirable chemical feedstock.

[0017] In a second aspect of the present invention, there is provided a method for upcycling plastic waste, comprising:

[0018] (i) contacting plastic from the plastic waste with an enzyme to degrade the plastic, thereby providing a composition comprising monomers and / or oligomers and / or derivatives thereof of the plastic and CO2;

[0019] (ii) photoreforming the composition to produce a product mixture comprising hydrogen, CO and oxidation products of the monomers and / or oligomers and / or derivatives thereof.

[0020] Advantageously, the second aspect of the invention produces a mixture of H2 and CO that can be used for synthesis gas and to generate additional chemicals.

[0021] In a third aspect of the present invention, there is provided a system for upcycling plastic waste, comprising:

[0022] (i) a degradation reactor for contacting plastic from the plastic waste with an enzyme to degrade the plastic, thereby providing a composition comprising monomers and / or oligomers and / or derivatives thereof of the plastic;

[0023] (ii) a photoreactor comprising a photocatalyst for photoreforming the composition to produce a product mixture comprising hydrogen and oxidation products of the monomers and / or oligomers and / or derivatives thereof, and

[0024] (iii) means for delivering a composition comprising monomers and / or oligomers of said plastic and / or derivatives thereof to said photocatalyst and / or photoreactor for photoreforming.

[0025] Advantageously, the system of the third aspect of the present invention provides a system for performing the methods according to the first and second aspects of the present invention.

[0026] definition

[0027] As used herein, the term "upcycling" refers to the conversion of material considered waste into valuable (typically usable) material.

[0028] As used herein, the term "plastic waste" refers to waste that contains one or more polymers and additives. Typically, the plastic waste is mixed, that is, it contains a mixture of different types or categories of polymers. Examples of plastic waste include used bottles, films, carrier bags, pallets and other forms of packaging.

[0029] As used herein, the term "plastic" refers to one or more polymers present in plastic waste.

[0030] The term "photoreforming" is known in the art, but for the avoidance of doubt refers to a process in which a photocatalyst converts H + The process of reducing organic compounds to hydrogen and oxidizing them. In a typical photoreforming process, electron-hole pairs are generated by irradiating a photocatalyst with light, and the electron-hole pairs both reduce the first species (usually H + ) and oxidizes the second species.

[0031] As used herein, the term "derivative" used with respect to monomers and oligomers refers to a compound derived from the monomer or oligomer by chemical transformation.

[0032] As used herein, the term "photocatalyst" refers to a catalyst system that is capable of absorbing light to generate electron-hole pairs and donating the electrons and holes to oxidized or reduced species.

[0033] As used herein, the term "photoactive material" refers to a material that is a photocatalyst capable of absorbing light to generate electron-hole pairs. The material may or may not be responsible for donating electrons or holes to the oxidized or reduced species.

[0034] As used herein, the term "co-catalyst" refers to a material that is capable of utilizing electrons or holes generated by a photoactive material to oxidize or reduce species and facilitate the overall process.

[0035] As used herein, the term "microparticle" refers to particles having an average diameter of 0.1 to 100 microns. Particle size is typically determined by laser diffraction.

[0036] As used herein, the term "nanoparticle" refers to particles having an average diameter of 1 to 100 nm. Particle size is typically determined by laser diffraction. DETAILED DESCRIPTION

[0037] Embodiments of various aspects of the invention are described below.For the avoidance of doubt, it will be understood that any embodiment as described herein in relation to one aspect of the invention will also apply to other aspects of the invention where appropriate.

[0038] A first aspect of the present invention relates to a method comprising:

[0039] (i) contacting plastic from plastic waste with an enzyme to degrade the plastic, thereby providing a composition comprising monomers and / or oligomers and / or derivatives thereof of the plastic; and

[0040] (ii) photoreforming the composition to produce a product mixture comprising hydrogen and oxidation products of the monomers and / or oligomers and / or derivatives thereof.

[0041] plastic waste

[0042] The plastic waste processed in the method of the present invention is preferably post-consumer plastic waste. This is plastic waste generated by end consumers. A typical example of post-consumer plastic waste is packaging.

[0043] Typically, plastic waste is collected from consumers along with glass, paper, and / or metal. In a preferred method of the present invention, plastic in the plastic waste is separated from glass, paper, and metal prior to step (i) of the method. Preferably, materials that could damage processing equipment (e.g., stone, wood, etc.) are also separated from the plastic. Therefore, a further preferred method of the present invention includes separating plastic from non-plastic contaminants in the plastic waste prior to step (i) of the method.

[0044] In another preferred method of the present invention, the plastic waste is washed (e.g. with water) before step (i) of the method. The separation and washing of the plastic can be carried out simultaneously or sequentially. Conventional equipment and methods can be used.

[0045] In the method of the present invention, the plastic from plastic waste is preferably in the form of a film, powder, pellets, fibers, microparticles, nanoparticles, or a combination thereof. Optionally, the plastic from plastic waste is subjected to protrusion or heating, and the resulting plastic is chopped, granulated, or ground before step (i) of the method of the present invention. Conventional equipment can also be used. In prior art methods, plastic is typically converted into fiber or powder form to increase the surface area of ​​the plastic for degradation. However, the need for such additional processing steps consumes energy.

[0046] A preferred form of plastic for use in the present method is a film. As explained in the Examples section, the present invention has proven highly effective when using films, despite the reduced surface area compared to the powders or fibers used in the prior art. The ability to use films directly eliminates the need for preliminary processing steps, thereby increasing the efficiency of the process.

[0047] Another preferred form of plastic for the method of the present invention is micro- or nanoparticles. Optionally, the micro- or nanoparticles can be present in a solution or dispersion. An advantage of the method of the present invention is that solutions or dispersions with low concentrations of plastic (e.g., 5 mg plastic / ml or less, or 1 mg plastic / ml or less) still produce hydrogen and oxidation products. Typically, prior art methods cannot achieve this without removing the particles from their solution / dispersion or at least increasing their concentration (which is expensive and time-consuming).

[0048] In a preferred method of the present invention, the plastic undergoing degradation is a condensation polymer. More preferably, the plastic undergoing degradation comprises polyester, and still more preferably, the plastic undergoing degradation consists of polyester. The polyester can be an aliphatic polyester or a semi-aromatic polyester. Another benefit of the present method is that polyester can be processed, as most commercial recycling operations focus on polyolefins.

[0049] Examples of suitable polyesters include poly(ethylene terephthalate) (PET), poly(butylene terephthalate) (PBT), polyethylene naphthalene (PEN), polytrimethylene terephthalate (PTT), polycaprolactone (PCL), polylactic acid (PLA), polyhydroxybutyrate (PHB), polyglycolic acid (PGA), polyethylene adipate (PEA), or combinations thereof. A preferred polyester is poly(ethylene terephthalate) (PET). Another preferred polyester is polycaprolactone (PCL).

[0050] enzymes

[0051] Enzymes are used to degrade plastics from plastic waste into monomers and / or oligomers and / or derivatives thereof, which can be oxidized during photoreforming. Enzymes are particularly advantageous over the alkaline solutions used in the prior art because they can operate at a friendly pH and can be highly selective for specific polymer types. It is therefore foreseeable that the method of the present invention can be used to upcycle polyesters from mixed plastics from plastic waste, and alternative processes can be used to upcycle other types of polymers.

[0052] It will be appreciated that the present invention is not particularly limited by the form in which the enzyme is provided. For example, the present invention is intended to encompass the direct use of the enzyme, as well as enzymes provided in cell lysates, cell secretions, or microorganisms. In a preferred method of the present invention, the enzyme itself is used.

[0053] In a preferred method of the invention, the enzyme degrades the plastic by hydrolysis. In a further preferred method, the enzyme is provided in an aqueous solution, and more preferably in an aqueous buffer solution. This allows the plastic to be easily mixed with the enzyme.

[0054] Preferably, the buffer solution has a buffer salt concentration of 0-500 mM, and more preferably has a concentration of 30-100 mM. Exemplary buffers include carbonate or phosphate ion buffers.

[0055] Preferably, the enzyme is selected from depolymerases, laccases, esterases, peroxidases, alkane hydroxylases, amidases, polyurethaneases, peptidases, tannases, lignin degrading enzymes, exopolysaccharide degrading enzymes, and combinations thereof. Preferably, the enzyme is an esterase. More preferably, the enzyme is an esterase selected from cutinase, carboxylesterase, PETase, and combinations thereof. Still more preferably, the enzyme is PETase or cutinase.

[0056] Exemplary enzymes suitable for use in the methods of the invention include those selected from the group consisting of native sequence IsPETase (A0A0K8P6T7), mono(2-hydroxyethyl)terephthalate hydrolase (A0A0K8P8E7), leaf and branch compost cutinase (LCC, G9BY57), Thermobifida fusca cutinase (TfCut, E5BBQ3_THEFU), Thermobifida fusca hydrolase (TfH, Q6A0I4), NylA (NYLA_PSES8) and NylB from strain NK87, Est1 (D4Q9N1) from T. alba AHK119; and variants thereof having greater than 75% sequence identity.

[0057] Enzymatic degradation step

[0058] In a preferred process of the invention, step (i) is carried out at a temperature of 25-100° C., such as 30-75° C. These relatively mild conditions are advantageous because they are inexpensive to operate and can be easily scaled up.

[0059] In other preferred methods of the present invention, step (i) is carried out at pH 4 to 12, optionally at pH 6 to 8. As mentioned above, the use of milder pH conditions can provide significant advantages for the scale-up and commercialization of the process compared to prior art methods.

[0060] In a preferred method of the invention, step (i) is performed for 4 hours to 7 days, more preferably for 12-48 hours, and even more preferably for about 24 hours.

[0061] In some methods of the present invention, the plastic is in an aqueous solution or dispersion. In such methods, the concentration of the plastic is preferably 0.1-100 mg / ml, more preferably 0.5-50 mg / ml, and still more preferably 1-30 mg / ml. In some methods of the present invention, the plastic is in an aqueous solution or dispersion and the concentration is 5 mg plastic / ml or less, such as 1 mg plastic / ml or less, or 0.5 mg plastic / ml or less.

[0062] Preferably, the aqueous solution is stirred or agitated during step (i).For example, the aqueous solution may be stirred at 30 to 1000 rpm.

[0063] In an alternative embodiment, the plastic is in a semi-aqueous solution. The concentration of the plastic in the semi-aqueous solution can be the same as described above for the aqueous solution.

[0064] In a preferred method of the present invention, the enzyme and the plastic are mixed in a weight ratio of 0.01 to 1.0% (weight ratio). 酶 / weight 塑料 More preferably, the enzyme and the plastic are present in a weight ratio of 0.05 to 0.4%.

[0065] Compositions obtained from degraded plastics

[0066] In preferred methods of the present invention, the composition obtained by degradation of plastics comprises monomers and / or oligomers of the plastics. In some cases, derivatives of the monomers and / or oligomers can be obtained. In preferred methods, the composition obtained by degradation primarily comprises monomers. This allows for the understanding that the composition undergoes oxidation. As demonstrated in the Examples, enzymes are effective in generating monomers from plastics, and these monomers can be oxidized into useful organic compounds.

[0067] Examples of monomers include 6-hydroxyhexanoic acid, ethylene glycol, methylene dianiline, bis(2-hydroxyethyl) terephthalate (BHET), mono(2-hydroxyethyl) terephthalate (MHET), 4-hydroxybutyric acid, terephthalic acid, 1,4-butanediol, naphthalene-2,6-dicarboxylic acid, 1,3-propylene glycol, lactic acid, 2-hydroxybutyric acid, 3-hydroxybutyric acid, glycolic acid, adipic acid and / or derivatives thereof, and combinations thereof.

[0068] In some methods of the invention, the method comprises: removing any solid residues from the composition comprising monomers and / or oligomers and / or derivatives thereof prior to step (ii).Solid residues may be removed, for example, by centrifugation of the composition.

[0069] In some methods of the invention, one or more of the degradation products of the plastic are removed from the composition. This may be advantageous if one of the products is found to interfere with the photoreforming reaction, thereby reducing the yield of the useful product produced.

[0070] In a preferred method of the present invention, the composition further comprises CO2. Optionally, the CO2 may be produced by degradation of the plastic. Alternatively or additionally, the CO2 may be added to the composition prior to step (ii). The CO2 may be a waste material from another process. The addition of CO2 may allow for simultaneous reduction of the CO2 and oxidation of monomers / oligomers derived from the plastic, thereby utilizing both waste materials to produce a new chemical product.

[0071] Photoreforming step

[0072] In a preferred method of the present invention, the composition undergoing photoreforming in step (ii) is an aqueous solution. Advantageously, the aqueous solution allows the production of hydrogen by the reduction of water. It is also desirable that the aqueous solution is used to maintain enzyme activity.

[0073] In some further preferred methods of the present invention, the composition comprising monomers and / or oligomers and / or derivatives thereof is used directly in step (ii). In other preferred methods, and as mentioned above, solids and / or specific compounds may optionally be removed. This is preferred if, for example, catalyst inhibition is likely to occur.

[0074] In the methods of the present invention, photoreforming can be performed using UV light, visible light, or a combination of the two. In some methods of the present invention, photoreforming is performed using visible light. In alternative methods, photoreforming is performed using UV and visible light. The light can be sunlight or artificial light (e.g., LED light). Sunlight is particularly advantageous because it allows photoreforming to directly utilize energy from the sun.

[0075] In some methods of the present invention, photoreforming is performed with light in the wavelength range of 250 to 700 nm and more preferably with light in the wavelength range of 400 to 700 nm.

[0076] In a preferred method of the present invention, photoreforming is performed using a photocatalyst comprising a photoactive material selected from the group consisting of metal oxides, chalcogenides, nitrides, carbon-based photosensitizers, dyes, nanoparticles such as quantum dots, perovskites, metal organic frameworks, covalent organic frameworks, or coordination polymers, or combinations thereof. Examples of suitable photoactive materials include TiO2, SrTiO3, Fe2O3, SnO2, ZrO2, W3, ZnO, CdS, CdSe, ZnS, ZnSe, CdTe, MoS2, GaN, InN, carbon-nitrides, carbon dots, graphene, molecular dyes, CsPbCl3, CsPbBr3, CsPbl3, Cs3Bi2Cl9, Cs3Bi2Br9, or Cs3Bi2l9, or combinations thereof.

[0077] In a preferred method of the present invention, photoreforming is performed using a photocatalyst comprising a photoactive material and a cocatalyst. Preferably, the cocatalyst comprises a transition element. Preferably, the cocatalyst comprises Pt, Pd, Ru, Ni, Co, Fe, Mn, Cu, Zn, or a combination thereof.

[0078] Examples of suitable cocatalysts include Pt, Ni2P, hydrogenases, phosphonated Re complexes, [Re(2,2′-bipyridine-4,4′-bisphosphonic acid)(CO)3(L)], where L = 3-methylpyridine or bromine, carbon monoxide dehydrogenase, and formate dehydrogenase.

[0079] In a preferred process of the present invention, the cocatalyst is capable of reducing carbon dioxide. An example of a cocatalyst capable of reducing carbon dioxide is bis(terpyridine)cobalt (CotpyP).

[0080] In some preferred methods of the present invention, the promoter is capable of reducing water to produce hydrogen.

[0081] In a preferred method of the invention, photoreforming is performed using an immobilized catalyst.

[0082] In a preferred method of the invention, photoreforming is performed at a pH of 6 to 8.

[0083] In a preferred method of the invention, photoreforming is carried out at a temperature of 15 to 50°C.

[0084] In a preferred method of the invention, photoreforming is performed for 2 to 96 hours.

[0085] Preferably, the oxidation products of the monomers and / or oligomers and / or derivatives thereof are selected from alcohols, aldehydes, ketones, amines, organic acids, carbon dioxide, derivatives thereof, or combinations thereof. For example, the oxidation products of the monomers and / or oligomers and / or derivatives thereof may be selected from formic acid, glycolic acid, oxalic acid, acetic acid, glyoxal, glycolaldehyde, valeraldehyde, hexanal, butyraldehyde, propionaldehyde, acetaldehyde, carbon dioxide, derivatives thereof, and / or combinations thereof.

[0086] In some methods of the present invention, one or more of the oxidation products of the monomers and / or oligomers and / or derivatives thereof are removed from the composition. This may be advantageous if one of the oxidizing species is found to interfere with the photoreforming reaction, thereby reducing the yield of the useful product produced.

[0087] A favorable combination

[0088] In a particularly preferred method of the present invention, the plastic comprises polyethylene terephthalate (PET), the enzyme comprises PETase, the photocatalyst comprises a photoactive material selected from metal oxides and nitrides, and the photocatalyst further comprises a co-catalyst selected from Pt, Pd, Ru, Ni, Co, Fe, Mn, Cu, Zn, or combinations thereof.

[0089] In another particularly preferred method of the present invention, the plastic comprises polycaprolactone (PCL), the enzyme comprises cutinase, the photocatalyst comprises a photoactive material selected from metal oxides and nitrides, and the photocatalyst further comprises a co-catalyst selected from Pt, Pd, Ru, Ni, Co, Fe, Mn, Cu, Zn, or combinations thereof.

[0090] In another particularly preferred method of the present invention, the plastic comprises poly(ethylene terephthalate) (PET) or polycaprolactone (PCL), the enzyme comprises PETase or cutinase, the photocatalyst comprises a photoactive material selected from metal oxides and nitrides, and the photocatalyst further comprises a co-catalyst capable of reducing CO2.

[0091] In the method of the present invention, steps (i) and (ii) can be performed separately or simultaneously. When performed simultaneously, these steps are preferably performed in a single reactor. Compared to prior art methods, performing these steps in a single reactor can improve operating efficiency, and surprisingly, these biological reactions and photocatalytic reactions are compatible and can occur simultaneously.

[0092] system

[0093] The present invention also relates to a system for upcycling plastic waste, comprising:

[0094] (i) a degradation reactor for contacting plastic from the plastic waste with an enzyme to degrade the plastic, thereby providing a composition comprising monomers and / or oligomers and / or derivatives thereof of the plastic;

[0095] (ii) a photoreactor comprising a photocatalyst for photoreforming the composition to produce a product mixture comprising hydrogen and oxidation products of the monomers and / or oligomers and / or derivatives thereof, and

[0096] (iii) means for delivering a composition comprising monomers and / or oligomers of said plastic and / or derivatives thereof to said photocatalyst and / or said photoreactor for photoreforming.

[0097] Preferably, the system includes means for capturing hydrogen.

[0098] Preferably, the system comprises means for collecting the oxidation products.

[0099] Preferably, the system may include a light source. Optionally, this may be provided separately.

[0100] Preferably, the system includes an immobilized photocatalyst (eg, a photocatalyst immobilized on a panel housed in a photoreactor).

[0101] A preferred system of the present invention is integrated. In a preferred integrated system, the degradation reactor is housed within a photoreactor. Particularly preferably, the photoreactor houses an immobilized photocatalyst (e.g., a photocatalyst affixed to a panel housed within the photoreactor). In this case, the means for delivering the composition comprising monomers and / or oligomers of plastic and / or derivatives thereof to the photocatalyst and / or photoreactor for photoreforming is preferably the reaction medium (e.g., water) in which the degradation occurs.

[0102] Therefore, a preferred system according to the present invention comprises:

[0103] (i) a degradation reactor for contacting plastic from said plastic waste with an enzyme in a reaction medium to degrade said plastic, thereby providing a composition comprising monomers and / or oligomers and / or derivatives thereof of said plastic;

[0104] (ii) a photoreactor comprising a photocatalyst for photoreforming the composition to produce a product mixture comprising hydrogen and oxidation products of the monomers and / or oligomers and / or derivatives thereof, wherein the degradation reactor is housed within the photoreactor; and

[0105] (iii) The means for delivering the composition comprising monomers and / or oligomers and / or derivatives of said plastic to said photocatalyst and / or photoreactor for photoreforming is the reaction medium in which degradation takes place.

[0106] In other words, a preferred system comprises a unitary photoreactor for upcycling plastic waste, the reactor comprising:

[0107] (i) a reaction medium comprising an enzyme for degrading the plastic to provide a composition comprising monomers and / or oligomers of the plastic and / or derivatives thereof; and

[0108] (ii) a photodecomposer for photoreforming the composition to produce a product mixture comprising hydrogen and oxidation products of the monomers and / or oligomers and / or derivatives thereof,

[0109] The reaction medium is capable of transporting the monomers and / or oligomers and / or derivatives thereof to the photocatalyst.

[0110] The invention will now be described by way of the following non-limiting examples.

[0111] Example

[0112] Unless otherwise stated, materials used in the examples are commercially available.

[0113] DuraPET enzyme expression and purification

[0114] The DuraPETase gene with a C-terminal Strep-tag was obtained as a synthetic gene (ThermoFischer) and then cloned into the E. coli (E. coli) expression vector pHAT5 using the restriction enzymes NcoI and XhoI (ThermoFischer FastDigest). To express and purify a single colony of DuraPETase from E. coli (Lucigen), the OverExpress TM C41 (DE3) transformants were grown in a 50 μg mL –1 The cells were grown as starter cultures in MDAG-135 non-inducing medium supplemented with carbenicillin (37°C; 200 rpm shaking; 24 h). ZYM-5052 medium was inoculated with the starter culture (1:100 v / v inoculation ratio) and incubated at 20°C with shaking at 300 rpm until growth saturation was reached for overexpression.

[0115] The cells were pelleted by centrifugation at 4000 x g for 10 minutes at 4°C and resuspended in buffer W (100 mM Tris (pH 8.0), 150 mM NaCl) before homogenization using an Emulsiflex C5. The lysate was clarified by centrifugation at 20,000 x g for 30 minutes and passed through a Strep-Tactin (IBA) gravity column. The purified DuraPETase was buffer exchanged into carbonate buffer (27 mM NaCO, 90 mM NaHCO (pH 8.5), 100 mM NaCl) using a PD-10 desalting column (GE Healthcare) and stored at 4°C for up to 4 days.

[0116] LCC expression and purification

[0117] The LCC gene was cloned into the pExp-Bla plasmid and transformed into Shuffled T7 expression cells (New England BioLabs, catalog number C3029J). The cells were grown in 1L LB medium containing 100 μg mL-1 ampicillin at 37°C until OD600nm reached 0.5 to 0.6. The expression of the recombinant protein was induced by adding 0.4mM IPTG at 20°C for 20h. The cells were harvested by centrifugation at 3434g for 20 minutes and resuspended in 20mL of 50 mM Tris-HCl pH 8.0 and lysed via Emulsiflex (Avestin). NaCl, imidazole and β-mercaptoethanol were added to the extract to a final concentration of 250mM, 10mM and 10mM, respectively. After lysis, cells were centrifuged at 11,000 g for 45 minutes at 4°C to remove cell debris, and the supernatant was loaded onto a nickel affinity resin (catalog number Super-NiNTA25, Protein Ark) previously equilibrated with a buffer solution [50 mM Tris-HCl pH 8.0, 250 mM NaCl, 10 mM imidazole, and 5% (v / v) glycerol]. Purification was performed using a stepwise imidazole gradient, and the purified fractions were analyzed on an SDS-PAGE gel. The fraction containing the purified LCC-pExp-Bla recombinant protein was selected to concentrate using an Amicon Ultra-15 filter (Merck-Millipore, catalog number UFC901024). A buffer solution containing 50 mM Tris-HCl pH 8.0, 100 mM NaCl, 2.5% (v / v) glycerol was added to the concentrated material, and the material was transferred to another concentration step. This concentration and dilution step was repeated three times to remove imidazole. To the final concentrated material, 0.1 mg of TEV protease was added for overnight cleavage, and the material was centrifuged at 11,000 g for 15 minutes at 4° C. to remove any precipitated protein. The supernatant was loaded onto a column containing resin previously equilibrated with a buffer containing 100 mM NaCl, 100 mM bicarbonate, pH 8.0, for a second purification step via IMAC.

[0118] Preparation of PCL membrane

[0119] PCL membranes were prepared by dissolving 200 mg of PCL flakes (average Mw of ~14,000 and average Mn of ~10,000 by GPC) in 10 mL of dichloromethane. 500 μL or 1 mL of the solution was evaporated in an open 1.5 mL tube at 86°C. The average size of the membranes used in the experiments was πrl (cone side surface) 5.34 cm 3 .

[0120] Preparation of PET film

[0121] PET films were used as purchased from Goodfellow. The average size of the films used in the experiments was 2 cm 3 The polymer is biaxially oriented and has a crystallinity of 6-8%.

[0122] Preparation of PET and PCL nanoparticles

[0123] Plastic nanoparticles were prepared using a precipitation and solvent evaporation technique. 50 mg of amorphous PET film (product code ES303015, Goodfellow GmbH, London, UK) or PCL flakes were dissolved in 1,1,3,3,3,-hexafluoro-2-propanol (5 mL) for at least one hour. This solution was added dropwise (1 mL / min) to the purified (MilliQ ® ) water (50 mL, cooled in an ice bath). Meanwhile, water was ® The agitator was stirred vigorously at 8000 rpm (IKA, Germany). The suspension was filtered using Whatman filter paper (8 μm diameter) and the remaining solvent was evaporated. Dynamic light scattering (Zetasizer Nano S) was used to obtain a particle size of d = 131.7 nm for PET and d = 184.9 nm for PCL.

[0124] Enzymatic treatment of plastic materials

[0125] Enzyme treatment 1 (Dura)

[0126] Dura enzyme stock solution was prepared as described above and spun at 14,000xg (4°C) for 10 minutes to remove protein precipitates. The protein concentration in the supernatant was determined by measuring the absorbance at 280nm using a Nanodrop ND-1000 spectrophotometer (Nanodrop Technologies). The supernatant was diluted to a concentration of 1 μM with carbonate buffer (27 mM Na2CO3, 90 mM NaHCO3 (pH 8.5), 100 mM NaCl), and 1 mL of the diluted enzyme solution was incubated with PCL or PET (film or nanoplastic) for 2 days. The incubation temperature was 37°C. Prior to the photocatalytic experiment, the solution was centrifuged at 20,000xg for 10 minutes to remove any solid residue from the solution.

[0127] Enzyme treatment 2 (LCC)

[0128] The LCC enzyme stock solution was prepared as described above and spun at 14,000xg (4°C) for 10 minutes to remove protein precipitates. The protein concentration in the supernatant was determined by measuring the absorbance at 280nm using a Nanodrop ND-1000 spectrophotometer (Nanodrop Technologies). The supernatant was diluted to a concentration of 1 μM with carbonate buffer (27 mM Na2CO3, 90 mM NaHCO3 (pH 8.5), 100 mM NaCl), and 1 mL of the diluted enzyme solution was incubated with PCL or PET (film or nanoplastic) for 2 days. The incubation temperature was 65°C. Prior to the photocatalytic experiment, the solution was centrifuged at 20,000xg for 10 minutes to remove any solid residue from the solution.

[0129] Quantification of the products after enzyme treatment was performed using reverse phase high performance liquid chromatography (HPLC).

[0130] Synthesis of photocatalysts / cocatalysts

[0131] TiO2|Pt photocatalysts were prepared by solution-processed platinization of P25 TiO2 nanoparticles (Evonik, anatase / rutile, 21 nm). 150 mg of TiO2 was dispersed in 10 mL of purified (MilliQ ® ) in water. Thereafter, 0.29 g of trisodium citrate dihydrate was added to the dispersion and then sonicated for another 30 minutes. 42 μL of H2PtCl6 solution (8% aqueous solution) was then added to the mixture. After another 20 minutes of sonication, a freshly prepared NaBH4 solution (5 mg dissolved in 1 mL of MilliQ ® After stirring for 30 minutes, the TiO2|Pt photocatalyst was separated by centrifugation, washed with water and dried at 80°C in air overnight.

[0132] CN x |Ni2P photocatalyst was prepared as follows. x Refers to polymeric carbon-nitride materials. It is understood that carbon-nitride is typically a material with a general simplified ratio of C3N4. First, 2g of melamine was heated to 550°C for 4h in a covered crucible under air (heating rate of 5°C min –1 ) to prepare unfunctionalized polymeric carbon-nitride (CN x ). Then 300 mg of the prepared CN x with NiCl2·6H2O (20 mg, 2 wt%) in a minimum amount of MilliQ ®The mixture was added to water (1 mL), stirred, and sonicated for 1 hour each. NaH2PO2·H2O was then added to the reaction mixture and stirred again for 1 hour, followed by sonication in a water bath for another 1 hour. The mixture was dried at 60°C in a vacuum, and the obtained dry solid was heated at 200°C for 1 hour under an Ar atmosphere (heating rate of 5° min –1 ). After cooling to room temperature, the CN x |Ni2P powder was washed with ethanol and water and dried at 60 °C in vacuum.

[0133] The TiO2|CotpP catalyst was synthesized according to the protocol reported in Leung, JJ et al., Solar-driven reduction of aqueous CO2 with acobalt bis(terpyridine)-based photocathode. Nat Catal 2, 354-365, doi:10.1038 / s41929-019-0254-2 (2019) and E. Lam, E. Reisner, Angew. Chem. Int. Ed. 2021, 60, 23306, and subsequently immobilized with TiO2 during photocatalysis.

[0134] Co-catalyst in photocatalyst (TiO2 or CN x The loading on )) was determined using inductively coupled plasma optical emission spectroscopy (ICP-OES).

[0135] Photoreforming catalysis for enzyme-treated plastics

[0136] 2 mg of photocatalyst powder (TiO2|Pt or CN x |Ni2P) was added to 1 mL of enzyme-pretreated plastic solution (pH ~6‒8) in a Pyrex glass photoreactor vial (internal volume: 7.91 mL) and sealed with a rubber septum. The photocatalyst was dispersed by water bath sonication for 25 minutes. Thereafter, the sample was purged with N2 (with 2% CH4 as an internal standard and leak control during gas analysis) for an additional 25 minutes. The sample was illuminated using a solar simulator (Newport Oriel) calibrated to 100 mW cm –2 (1 sun) and equipped with an Air Mass 1.5 Global (AM1.5 G) filter and a water filter for removing infrared radiation. The temperature was maintained at 25°C and the sample was stirred at 600 rpm during irradiation.

[0137] Integrated enzyme processing and photoreforming catalysis

[0138] Initially, a TiO2|Pt photocatalyst panel was prepared. A frosted glass panel (4.5 × 4.5 cm 2 ) were purified (MilliQ ® ) water, isopropanol, and acetone were ultrasonically cleaned for 15 min each and then dried under N2 flow. The TiO2|Pt photocatalyst was dispersed in ethanol (20 mg mL –1 ) in: probe-sonication (10 min, 30 s pulses at 100% amplitude followed by 5 s pauses), followed by addition of 1 vol% Nafion TM The dispersion was carefully drop-cast onto a clean ground glass (16 μL cm at a time). –2 ) and dried for 10 min before adding subsequent layers (6 layers added in total; final catalyst loading was ~1.92 mgcat cm –2 The prepared TiO2|Pt panel was then annealed at 80°C in air overnight.

[0139] The TiO2|Pt photocatalyst panel (effective area 3.5 × 3.5 cm 2 ) was mounted on a custom-made airtight PEEK reactor equipped with a quartz window. 12 mL of carbonate buffer with LCC enzyme (concentration: 1 μM) and a piece of transparent PET film (weight ~ 240 mg) were added to the reactor and then properly sealed. The solution was purged with N2 (using 2% CH4 as an internal standard) and the reactor was then placed in a calibrated Newport Oriel solar simulator (AM 1.5G, 100 mW cm –2 ). The steady-state temperature inside the reactor was measured to be ~33°C, and the solution was not stirred during the experiment. Aliquots of the solution were taken at regular intervals to assess PET hydrolysis using HPLC-UV, and the gas from the headspace (50 μL) was analyzed for H evolution using GC (discussed below). Control experiments were performed in pure blank buffer.

[0140] Photoreforming of enzymatically treated PET for CO2 reduction

[0141] Enzyme pretreatment 2 (LCC) was performed on PET films. Experiments were then performed directly using the enzyme pretreatment solution or after removing TPA from the LCC-pretreated PET solution. To remove TPA, the solution was acidified to pH 3 with 1M HCl, resulting in the precipitation of TPA as a white precipitate. The suspension was then filtered using a 0.2 mm syringe filter to obtain a clear solution. The clear solution was then neutralized with 1M NaOH to an initial pH of 6.5.

[0142] In a glass photoreactor, 5 mg of TiO2 was suspended in 1 mL of enzyme-treated PET solution before or after TPA precipitation (see above), followed by 2 mL of MeCN. A known amount (25 or 50 nmol) of the molecular catalyst CotpP (from a freshly prepared 2 mM H2O solution; 0.0125 mL for 25 nmol CotpP or 0.025 mL for 50 nmol CotpP) was added while stirring. The photoreactor (~3 mL of solution) was capped with a rubber septum and purged with CO2 containing 2% CH4 as an internal gas chromatography standard for 15 minutes, followed by stirring in the dark for 15 minutes. The photoreactor (maintained at 25°C and stirred at 600 rpm) was then irradiated with simulated solar radiation (AM 1.5G, 100 mW cm-2) equipped with a water filter to remove infrared radiation. −2 The photocatalytic process was monitored periodically by sampling the headspace (typically after 24 and 48 h) by GC to monitor H2 and CO formation. 1 The products in solution (formate) were detected by H NMR spectroscopy in D2O (1:1 v:v photocatalytic solution: D2O). The turnover number (TON) was calculated based on CotyP, assuming all cobalt sites were active catalytic sites.

[0143] Product detection and quantification

[0144] The generation of H2 and / or CO was detected and estimated by manually injecting the gas from the reactor headspace (50 μL) into a Shimadzu GC-2010 PlusGC and quantified using CH4 as an internal standard. Maleic acid was used as an internal standard. 1 H NMR spectroscopy ( 1 H-NMR) was used to detect and quantify the oxidation products in the solution photoreforming and post-catalysis. An Agilent 7890A GC equipped with a flame ionization detector (FID) and a thermal conductivity detector (TCD) was used to detect CO2 and hydrocarbons.

[0145] The measured value is expressed as the gas (H2 or CO) yield per unit weight of substrate (µmol g sub –1) and the activity of the photocatalyst per unit weight per hour (µmol g cat –1 h –1 For experiments using the integrated system, H2 evolution data are expressed as the airborne efficiency of the photocatalyst panel (µmol m irr –2 ).

[0146] Unless otherwise stated, analytical measurements were performed in triplicate and expressed as unweighted means ± standard deviations.

[0147] Use of oxidation products 1 Analyze by H NMR spectroscopy or gas chromatography.

[0148] result

[0149] Processing of PCL and PET substrates

[0150] Typical results from enzyme treatment of PCL and PET polymer substrates are shown in Table 1 along with a comparative base treatment (2 M NaOH). The molar yields of monomers are provided after 2 hours, 4 hours, 1 day, 2 days, and 7 days. The monomers detected were 6-hydroxyhexanoic acid (HA) for PCL and terephthalic acid (TPA) for PET.

[0151] Compared to base treatment under the same incubation conditions, higher monomer yields were observed for both polyesters with enzyme treatment. Furthermore, different sizes of plastics were observed to be sensitive to enzyme treatment. Both LCC and Dura exhibited degradation activity against PET and PCL nanoplastics (130-185 nm), with increases in molar yield relative to substrate mass ratio of approximately 4-fold for PET and 8-fold for PCL after 2 days of incubation compared to those using membranes.

[0152] Table 1

[0153]

[0154] Table 2 shows the results of the method of the present invention, demonstrating the production of H2 from PCL and PET polymers after enzymatic degradation. It also includes some comparative data (C1-C4) for photoreforming catalysis of solutions obtained from degradation of PET polymer using alkaline solutions. As can be seen, the results using the enzyme-treated solutions show surprisingly high H2 yields compared to prior art methods that utilize well-known alkaline conditions to degrade plastic materials. Although C3 shows a relatively high H2 yield (comparable to Example 6 of the present invention, which also utilizes a TiO2|Pt photocatalyst), C3 uses the photocatalyst at a significantly higher concentration and utilizes a significantly higher Pt loading, both of which would be expected to provide improved performance. This example also utilizes harsh pretreatment conditions (10 M NaOH). Furthermore, comparing the catalyst activities of Example 6 and C3, it can be seen that the use of the enzyme pretreatment results in a significant improvement in performance compared to the alkaline pretreatment (518 umol g-cat, respectively). -1 h -1 with 153 umol g-cat -1 h -1 ). Surprisingly, this higher hydrogen generation activity can be achieved without harsh pretreatment conditions. In addition, all comparative examples utilized PET powders (C1-C3) or microfibers (C4) with significantly higher surface areas than the PET films used in the embodiments of the present invention, and therefore these comparative methods would be expected to show higher activity than the embodiments of the present invention. In addition, the microfibers exhibited lower crystallinity (<3%) than the PET films used in the embodiments of the present invention (≈6%), and alkaline hydrolysis has been reported to be more effective for low crystalline polymers (Polymers 2020, 12(10), 2195; Polym. Sci., 51: 99-109; Biomaterials, 16, 11,1995, 833-843).

[0155] For PET films (Examples 5 and 6), it was observed that the use of the LCC enzyme (enzyme treatment 2) in combination with photoreforming resulted in exceptionally high H2 yields. The primary oxidation product identified in these experiments was formate. Without wishing to be bound by theory, it is believed that the high H2 yields are due to the enzyme's effectiveness at hydrolyzing PET (at 65°C), which produces a high concentration of monomers (EG / TPA) for subsequent oxidation. Table 3 also compares Example 6 with three control experiments, C5, C6, and C7. C5 and C6 show very little H2 evolution in the absence of polymer or enzyme. C7, meanwhile, demonstrates the relevance of a cocatalyst. Furthermore, in other control experiments performed without any photocatalyst or light, no H2 production was observed.

[0156] The highest yield was observed for PCL membranes from photoreforming catalysis after treatment with Dura enzyme (enzyme treatment 1). As can be seen, the major oxidation products identified were valeraldehyde and CO2 with trace amounts of formate and hydrocarbons. Without wishing to be bound by theory, the observed valeraldehyde:CO2 ratio of ~1:1 may be due to the formation of 6-hydroxyhexanoic acid by enzyme treatment of PCL membranes that have undergone 2e generation of holes using light. - Oxidation to form 6-oxohexanoic acid (OA). Thereafter, decarboxylation of OA yields CO2 and valeraldehyde in equimolar ratios.

[0157] The use of TiO2|Pt photocatalysts is relatively x |The use of Ni2P photocatalyst increased the yield. However, CN x |Ni2P has the ability to absorb in the visible region and is noble metal-free, in contrast to TiO2|Pt which absorbs mainly in the UV region.

[0158] Examples 7-13 show the results of using enzymes to degrade solutions of nanoplastic substrates. The concentration of nanoplastic used for treatment was ~0.1 mg mL –1 Surprisingly, hydrogen production could be observed using such low concentrations. The H2 yield and activity followed similar trends as in the case of PET and PCL films. Due to the low initial plastic concentration (relative to the amount of H2 produced), the substrate-normalized H2 yield of the nanoplastic was significantly higher.

[0159] Table 4 shows the results of simultaneous H2O (H + ) and CO2 reduction experiments to produce synthesis gas. CotpyP was used as a cocatalyst, which is a Co-based catalyst coordinated by two terpyridine ligands. 2+ A molecular CO2 reduction catalyst, a terpyridine ligand bearing a phosphonate group for anchoring to TiO2, is described. Example 14 demonstrates the production of CO and H2 from PET film using TiO2|CotpyP in combination with enzyme treatment. Examples 15 and 16 demonstrate that syngas yield can be increased by removing TPA monomer prior to photocatalysis. Without wishing to be bound by theory, this is believed to be due to TPA inhibition of the cobalt catalyst.

[0160] Table 5 shows the results from an integrated enzyme treatment and photoreforming catalytic experiment for direct H2 production from PET film. The data are provided at intervals up to 96 hours. TiO2|Pt photocatalyst was used in the reactor with LCC enzyme.

[0161] It was observed that with the increase in enzyme mediated hydrolysis of the PET film, the amount of H2 produced also increased. Changes in the texture and transparency of the PET film were also observed after the experiment. Without wishing to be bound by theory, it is believed that this is due to the enzymatic attack on the film. This indicates that the enzyme is active under the given conditions, thereby producing monomers of ethylene glycol (EG) and terephthalic acid (TPA) by hydrolysis of PET. The EG formed from PET can be oxidized in situ by the panel to produce organic matter, while generating H2 from the solution. After 96 hours of photoreforming, the solution 1 H-NMR spectroscopy confirmed the presence of formate as an EG oxidation product. A control experiment using a blank buffer solution in the absence of plastic showed negligible H production after 96 h. This performance confirmed the suitability of combining the photoreforming system with enzyme treatment to produce H in a single chamber.

[0162]

[0163]

[0164]

[0165]

[0166]

[0167] Table 5

[0168]

Claims

1. A method for upcycling plastic waste, the method comprising: (i) contacting plastic from the plastic waste with an enzyme to degrade the plastic, thereby providing a composition comprising monomers and / or oligomers and / or derivatives thereof of the plastic; and (ii) photoreforming the composition to produce a product mixture comprising hydrogen and oxidation products of the monomers and / or oligomers and / or derivatives thereof.

2. The method according to claim 1, wherein the plastic is in the form of a film, fiber, powder, granule, microparticle, nanoparticle or a combination thereof, preferably in the form of a film or nanoparticle.

3. The method according to claim 1 or 2, wherein the plastic comprises, preferably consists of, polyester.

4. The method according to claim 3, wherein the polyester is selected from poly(ethylene terephthalate) (PET), poly(butylene terephthalate) (PBT), polyethylene naphthalate (PEN), polytrimethylene terephthalate (PTT), polycaprolactone (PCL), polylactic acid (PLA), polyhydroxybutyrate (PHB), polyglycolic acid (PGA), polyethylene adipate (PEA) or a combination thereof, preferably selected from poly(ethylene terephthalate) (PET) or polycaprolactone (PCL).

5. The method according to any one of claims 1 to 4, wherein the enzyme is selected from the group consisting of depolymerases, laccases, esterases (such as cutinases, carboxylesterases, PETases), peroxidases, alkane hydroxylases, amidases, polyurethaneases, peptidases, tannases, lignin degrading enzymes, exopolysaccharide degrading enzymes, and combinations thereof.

6. The method of claim 5, wherein the enzyme is PETase or cutinase.

7. The method of claim 5, wherein the enzyme is selected from the group consisting of native sequence IsPETase (A0A0K8P6T7), mono(2-hydroxyethyl)terephthalate hydrolase (A0A0K8P8E7), leaf and branch compost cutinase (LCC, G9BY57), Thermoascus aurantiacus cutinase (TfCut, E5BBQ3_THEFU), Thermoascus aurantiacus hydrolase (TfH, Q6A0I4), NylA (NYLA_PSES8) and NylB from strain NK87, Est1 (D4Q9N1) from thermophilic alkalitolerant actinomycete AHK119; and variants thereof having greater than 75% sequence identity.

8. The method according to any one of claims 1 to 7, wherein the composition comprises monomers of the plastic.

9. The method according to claim 8, wherein the monomer is selected from the group consisting of 6-hydroxyhexanoic acid, ethylene glycol, methylene dianiline, bis(2-hydroxyethyl) terephthalate (BHET), mono(2-hydroxyethyl) terephthalate (MHET), 4-hydroxybutyric acid, terephthalic acid, 1,4-butanediol, naphthalene-2,6-dicarboxylic acid, 1,3-propylene glycol, lactic acid, 2-hydroxybutyric acid, 3-hydroxybutyric acid, glycolic acid, adipic acid and / or derivatives thereof and combinations thereof.

10. The method according to any one of claims 1 to 9, wherein the composition further comprises CO2.

11. The method of claim 10, wherein CO2 is added to the composition prior to step (ii).

12. The method according to any one of claims 1 to 11, wherein the composition undergoing photoreforming is an aqueous solution.

13. The method according to any one of claims 1 to 12, wherein the photoreforming is performed using visible light.

14. The method according to any one of claims 1 to 13, wherein the photoreforming is performed using a photocatalyst, the photocatalyst comprising a photoactive material selected from metal oxides, chalcogenides, nitrides, carbon-based photosensitizers, dyes, nanoparticles (such as quantum dots), perovskites, metal organic frameworks, covalent organic frameworks or coordination polymers or combinations thereof.

15. The method according to any one of claims 1 to 14, wherein the photoreforming is performed using a photocatalyst, the photocatalyst comprising a photoactive material selected from TiO2, SrTiO3, Fe2O3, SnO2, ZrO2, W3, ZnO, CdS, CdSe, ZnS, ZnSe, CdTe, MoS2, GaN, InN, carbon-nitrides, carbon dots (cots), graphene, other two-dimensional materials, molecular dyes, CsPbCl3, CsPbBr3, CsPbl3, Cs3Bi2Cl9, Cs3Bi2Br9 or Cs3Bi2l9 or a combination thereof.

16. The method according to any one of claims 1 to 15, wherein the photoreforming is performed using a photocatalyst comprising both a photoactive material and a co-catalyst.

17. The method of claim 16, wherein the promoter comprises any hydrogen evolution catalyst and the elements Pt, Pd, Ru, Ni, Co, Fe, Mn, Cu, Zn, or a combination thereof.

18. The method according to claim 16 or 17, wherein the co-catalyst comprises Pt, Ni2P, hydrogenase, phosphonated Re complex, [Re(2,2′-bipyridine-4,4′-diphosphonic acid)(CO)3(L)], carbon monoxide dehydrogenase or formate dehydrogenase, wherein L=3-methylpyridine or bromine.

19. The method of any one of claims 16 to 18, wherein the promoter is capable of reducing carbon dioxide, optionally wherein the promoter is bis(terpyridine)cobalt (CotpyP).

20. The method according to any one of claims 1 to 19, wherein the oxidation products of the monomers and / or oligomers and / or derivatives thereof are selected from alcohols, aldehydes, ketones, amines, organic acids, carbon dioxide, derivatives thereof or combinations thereof.

21. The method according to claim 20, wherein the oxidation products of the monomers and / or oligomers and / or derivatives thereof are selected from formic acid, glycolic acid, oxalic acid, acetic acid, glyoxal, glycolaldehyde, valeraldehyde, hexanal, butyraldehyde, propionaldehyde, acetaldehyde, carbon dioxide, derivatives thereof and / or combinations thereof.

22. The process according to any one of claims 1 to 21, wherein steps (i) and (ii) are carried out simultaneously in a single reactor.

23. A method for upcycling plastic waste, the method comprising: (i) contacting plastic from the plastic waste with an enzyme to degrade the plastic, thereby providing a composition comprising monomers and / or oligomers and / or derivatives thereof of the plastic and CO2; (ii) photoreforming the composition to produce a product mixture comprising hydrogen, CO and oxidation products of the monomers and / or oligomers and / or derivatives thereof.

24. A system for upcycling plastic waste, the system comprising: (i) a degradation reactor for contacting plastic from the plastic waste with an enzyme to degrade the plastic, thereby providing a composition comprising monomers and / or oligomers and / or derivatives thereof of the plastic; (ii) a photoreactor comprising a photocatalyst for photoreforming the composition to produce a product mixture comprising hydrogen and oxidation products of the monomers and / or oligomers and / or derivatives thereof, and (iii) for conveying a composition comprising monomers and / or oligomers and / or derivatives of said plastic to said device comprising a photocatalyst and / or a photoreactor for photoreforming.

25. The system of claim 24, wherein the degradation reactor and the photoreactor are integrated.

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