• Filatech Corporation
• •
• 03 Jun 2025
• •

Unlocking the Future of Waste: Chemical Recycling of Hard-to-Recycle Plastics

Introduction

While traditional recycling methods struggle to process complex, multi-layered, or contaminated plastics, chemical recycling emerges as a powerful solution. Unlike mechanical recycling, which reshapes plastics without altering their chemical structure, chemical recycling breaks polymers down into their fundamental building blocks—monomers or other valuable compounds—allowing the creation of virgin-quality plastic or fuels.

Let’s explore various chemical recycling methods, their benefits and drawbacks, the products obtained, and their applications, following a logical path from thermal and catalytic processes to biological and emerging innovations.

Thermal and Catalytic Recycling Technologies

1. Pyrolysis

Process: Heats plastic waste in an oxygen-free environment.
Pros: Converts plastic into fuel oil, waxes, and gases.
Cons: High energy consumption; potential toxic byproducts.
Use: Alternative fuel production and chemical feedstock.

2. Thermolysis

Process: Thermal cracking of plastics.
Pros: Energy recovery; works on mixed waste.
Cons: High temperature requirements; limited product control.
Use: Industrial energy systems.

3. Gasification

Process: Converts plastic into syngas using limited oxygen.
Pros: Efficient; accepts contaminated plastic streams.
Cons: Complex setup; syngas cleaning required.
Use: Fuel, electricity, or chemical synthesis.

4. Catalytic Plastic Recycling

Process: Uses catalysts to improve breakdown efficiency.
Pros: Lower energy use; precise output.
Cons: Catalyst regeneration and cost.
Use: Fuel, wax, or monomer recovery.  

5. Microwave-Assisted Depolymerization

Process: Uses microwaves and solution-phase catalysts.
Pros: Rapid reaction; energy savings.
Cons: High-tech investment; limited data.
Use: Advanced monomer recovery.

6. Bio-TCat™ by Anellotech

Process: Thermocatalytic process for biomass and plastics.
Pros: Bio-based; produces high-value BTX chemicals.
Cons: Feedstock must be controlled.
Use: New plastic and chemical production.

Solvent and Chemical Depolymerization 

7. Solvent-Based Recycling 

Process: Dissolves and purifies polymer before recovery.
Pros: Maintains polymer quality; good for composites.
Cons: Solvent handling and emissions.
Use: Film and multilayer recovery. 

8. Depolymerisation Solvolysis / Reactive Recycling

Process: Chemical depolymerization using solvents and heat.
Pros: High-purity monomers.
Cons: Feedstock-specific and cost-sensitive.
Use: PET and nylon depolymerization. 

9. Chemolysis

Process: Acid, alkali, or alcohol-based breakdown of plastics.
Pros: Efficient for specific polymers.
Cons: Limited flexibility across plastic types.
Use: PET, PUR, and polyester recycling.

10. Hydrolysis 

Process: Water breaks down ester bonds in polyesters.
Pros: Green chemistry approach.
Cons: Requires high pressure/temperature.
Use: PET to terephthalic acid and ethylene glycol.

11. Hydrochemolytic Technology 

Process: Hybrid of hydrolysis and chemical catalysis.
Pros: Broad plastic range; moderate conditions.
Cons: Early-stage adoption.
Use: Mixed plastic streams.

12. Iron Trichloride and Sunlight

Process: Ferric chloride reacts with oxygen under sunlight to break plastics.
Pros: Mild, low-energy.
Cons: Scalability uncertain.
Use: Experimental photodegradation. 

13. Alcoholysis with Soluble Iron Catalyst

Process: Breaks down polyesters with alcohol and iron catalyst.
Pros: Efficient monomer recovery.
Cons: Laboratory scale.
Use: PET recycling to high-purity components.
Bio-Based and Enzymatic Processes

14. Enzymatic Depolymerisation

Process: Enzymes digest polymers into monomers.
Pros: Highly selective and green.
Cons: Cost and speed challenges.
Use: Food-grade PET recovery.

15. Microbial Decomposition

Process: Microbes consume plastic as a carbon source.
Pros: Natural; low energy.
Cons: Slow; limited plastic range.
Use: Bioremediation of plastic-polluted areas.

16. Biodegradation & Bioconjugates 

Process: Bio-based enhancements aid natural breakdown.
Pros: Supports end-of-life disposal.
Cons: Not recycling per se; downcycling risk.
Use: Compostable films and bags.

Light, Mechanical and Hybrid Innovations

17. Photocatalyst Chemical Recycling 

Process: Light-driven catalysts degrade plastics.
Pros: Solar-powered; selective degradation.
Cons: Experimental; durability issues.
Use: Field degradation in marine or landfill settings.

18. Recycling with Mechanochemistry

Process: Uses grinding/mechanical stress to drive reactions.
Pros: Solvent-free; eco-friendly.
Cons: Low throughput today.
Use: Academic and small-scale applications.  

19. Reactive Extrusion

Process: Extrusion combined with in-line chemical reactions.
Pros: Scalable; integrates into existing equipment.
Cons: Requires careful reaction control.
Use: Upcycled polymer composites and blends.

Advanced Catalysts & Specialized Uses

20. Flame Retardants as Depolymerization Catalysts

Process: Dual-function agents aid in recycling and fire resistance.
Pros: Multifunctional; reduces additive load.
Cons: Health and safety concerns.
Use: E-waste and auto plastic recycling.

21. GFRP to Silicon Carbide

Process: Converts reinforced plastic into valuable ceramic.
Pros: Upcycles high-tech waste.
Cons: Energy and process complexity.
Use: Aerospace and semiconductor sectors.

Conclusion:

The Road to a Circular Plastic Economy
Each chemical recycling process offers unique strengths and limitations. While some excel at recovering pure monomers, others turn waste into energy or high-value products. A truly circular economy will likely depend on a combination of these methods.

To scale these sustainably, industries must invest in infrastructure, catalyst innovation, and product design that prioritizes recyclability. 

Chemical recycling, when responsibly implemented, transforms waste from a problem into a valuable resource—unlocking a cleaner, more circular future.

Manjul Goswami
Director