What Kind of Oil Can Be Obtained from Catalytic Plastic Pyrolysis?

As plastic waste continues to rise globally, catalytic pyrolysis (also called catalytic cracking) has emerged as one of the most promising technologies for converting waste plastics into valuable resources. One of the primary products of this process is plastic pyrolysis oil—but what kind of oil is it exactly? What are its properties, potential uses, and how does it compare to conventional fuels?

What Is Catalytic Pyrolysis of Plastics?

Catalytic pyrolysis is a thermochemical process that breaks down plastic polymers at high temperatures (typically 350–600°C) in the absence of oxygen, using a catalyst to lower reaction temperatures and enhance oil quality. This process produces a mixture of gas, liquid (oil), and solid (char), with the liquid fraction often being the most commercially valuable.

The type and yield of oil depend on:

• Feedstock (e.g., PE, PP, PS, PVC, PET)

• Catalyst type (zeolites, silica–alumina, etc.)

• Reaction temperature and time

What Types of Oil Are Produced?

The oil obtained from catalytic plastic pyrolysis plant is usually a hydrocarbon-rich liquid, which can be broadly categorized into the following types:

1. Pyrolysis Oil (Unrefined)

• Appearance: Dark brown to black, viscous liquid

• Composition: A mixture of alkanes, alkenes, aromatics, and sometimes oxygenated compounds

• Applications: Can be used as industrial fuel in furnaces, boilers, cement kilns, or further upgraded

2. Light Fuel Oil (Refined)

• Appearance: Yellow to light brown, less viscous

• Composition: C5–C20 hydrocarbons, similar to diesel or kerosene fractions

• Applications: After distillation and treatment, it can be used in diesel engines or as a blending agent

3. Naphtha-like Fraction

• Lighter hydrocarbons (C5–C10 range)

• Potential feedstock for producing new plastics or petrochemicals via steam cracking

• Suitable for refining into gasoline components

Key Properties of Plastic-Derived Oil

• Calorific value: ~40–45 MJ/kg (comparable to diesel)

• Sulfur content: Generally low, depending on feedstock

• Density: Varies from 0.75 to 0.95 g/cm³

• Flash point: Often lower than conventional diesel; may need to be improved for safe storage

The exact quality depends heavily on the catalyst and process parameters used. Zeolite-based catalysts like ZSM-5 are known to enhance aromatic content and produce more stable, lighter fractions.

How Is It Used?

Plastic pyrolysis oil has versatile applications:

• Industrial Fuel: Used directly or after minimal refining in heavy machinery and factories.

• Diesel Substitute: After distillation and hydro-treatment, it can serve as a partial or full replacement for diesel.

• Petrochemical Feedstock: Especially the lighter fractions, which can be cracked to make ethylene, propylene, and other building blocks for new plastics.

Environmental and Economic Impact

Using catalytic pyrolysis to convert plastic waste into oil offers multiple benefits:

• Reduces landfill volume and marine pollution

• Provides an alternative to fossil fuels

• Enables circular economy models by turning waste into raw materials

However, challenges remain in oil upgrading, catalyst regeneration, and regulatory approval for using pyrolysis oil as transport fuel in many countries.

Conclusion

Catalytic pyrolysis is more than just a waste treatment solution—it's a resource recovery strategy. The oil obtained from this process can range from heavy industrial fuel to refined diesel alternatives and petrochemical feedstocks, depending on the technology and conditions applied.

As research advances and regulatory frameworks adapt, plastic pyrolysis oil may soon become a mainstream alternative in the global energy and materials markets.