What is Chemical Recycling?

Chemical recycling explained

Chemical recycling is a method for repurposing plastic scraps into useful byproducts that can promote the circular economy. Plastics originate from oil or petroleum and are created through a polymerization process, with major polymer substances like PET, HDPE, LDPE, PVC, PP, and PS being common

Although the idea of using plastic may seem backwards in this day of eco-consciousness, the material has many desirable properties. Plastics have had a huge impact on many different industries, but none more so than healthcare, where they are crucial for the protection of both patients and medical staff. Sadly, a great deal of plastic pollutes our ecosystem. What’s the good news? Chemical recycling is a method for repurposing plastic scraps into useful byproducts that can be used to promote the circular economy.

How to recycle plastic: the fundamentals

Define plastics, 

Understanding that plastics originate from oil or petroleum and are created through a polymerization process is crucial to getting a handle on the idea of chemical recycling. This means they have molecular chains that can be joined together to form polymers.

The major polymer substance used to make plastic is used to classify that plastic. Polyethene terephthalate (PET), high-density polyethene (HDPE), low-density polyethene (LDPE), polyvinyl chloride (PVC), polypropylene (PP), and polystyrene (PS) are some of the most common plastics we use every day. These polymers range widely in terms of size, colour, function, and plastic recycling.

How do we recycle plastics?

Annual global plastic production is 380 million tons. Plastic trash was previously recycled exclusively through mechanical means, which entailed grinding, sorting, washing, melting, and chilling to produce granulated recycled plastic. However, this method can only be used on specific plastics that are made up of a single polymer. It’s simple to recycle common plastics like PET soda bottles and HDPE milk jugs.

However, in reality, many plastic goods are made up of different polymers, have numerous layers of plastic, or are soiled with food and dirt. This makes mechanical recycling of them impractical or prohibitively expensive. Instead, they are either burned or buried. Because of this, only around 15% of plastics in Europe and 9% in the US are recycled. Furthermore, most plastics that are recycled end up being downcycled, meaning they are transformed into lower-quality goods.

An Overview of Chemical Waste Reuse

When do chemicals get recycled?

New avenues of exploration are made possible by the chemical recycling of plastic trash.

What’s the deal? Plastic trash can be chemically recycled into its molecular components. The chemical makeup of polymers in plastic is altered by this process, allowing for their recovery and subsequent use as a petrochemical feedstock or in the production of new polymers.

What goes into the process of chemically recycling plastics?

Chemical recycling can refer to a number of different methods and technologies. The technologies can be divided into three groups according to where their output fits into the plastics supply chain:

• When polymers are dissolved in solvents, the additives are washed away. The plastic breaks down and reforms as a polymer. The polymers can be reprocessed into a variety of other plastics.
• Through the application of chemicals, solvents, and heat, polymers can be depolymerized into their component molecules (monomers), which can subsequently be recycled into the plastics industry.
• Through a series of chemical, thermal, or catalytic reactions in a reactor, plastic waste can be converted into a gas (gasification) or a liquid, oil-like feedstock (pyrolysis) that can be further refined into refined hydrocarbons or petrochemicals.

Reusing raw materials by pyrolysis

Basic chemicals (such as hydrocarbons or syngas) are the result of feedstock recycling, and these must undergo additional processing to create polymers. Two methods exist for accomplishing this goal:

• The process of gasification involves the high-temperature heating of waste materials (about 1000–1500 °C) under low-oxygen conditions. Oxygen decomposes the molecules into their elemental forms. The resulting syngas are used to create a number of chemicals (including methanol, ammonia, hydrocarbons, and acetic acid) that are then put to use in the plastics industry, as well as in the manufacturing of fuel and fertilizer.

• The process of pyrolysis (thermal cracking) involves heating plastic waste to temperatures above 400 °C in an oxygen-depleted environment. Long polymer chains are broken down into simpler hydrocarbon products such as gas, wax, diesel, and naphtha that can be used as fuel or recycled back into polyethene and polypropylene at petrochemical plants.

The merits of chemical recycling, in particular pyrolysis

It allows for the recycling of previously unrecyclable plastic

In contrast to mechanical recycling, chemical recycling can be used for polluted and mixed-polymer waste streams. However, most chemical recycling methods have certain limitations. ‘Condensation’ polymers like polyethene terephthalate (PET) and polyamides are the only ones that can undergo chemical depolymerization. However, pyrolysis breaks down ‘addition’ polymers like polyethene (PP), polypropylene (PE), and polyvinyl chloride (PVC), which account for the vast bulk of plastic trash.

Interesting fact: PET can’t be recycled in a pyrolysis plant since it includes oxygen. Mechanical recycling, which typically focuses on PET bottles, is complemented by pyrolysis in

It yields plastics that are on par with those made from raw materials.

Chemical recycling is a process that breaks down plastic trash into usable chemicals and plastics. This recycled plastic is ideal for applications where quality matters, including in food packaging.

It helps conserve fossil fuels.

Plastics that have been chemically recycled can be used as feedstock for making new plastics, reducing the demand for newly mined fossil fuels.

• Limits carbon dioxide output
• In contrast to incineration and energy recovery, chemical recycling produces no emissions.

There is huge potential for growth in the chemical recycling industry

The need for recycled plastics has increased alongside the widespread usage of plastics. Coca-Cola, PepsiCo, and Unilever are just a few examples of consumer goods firms that have made significant pledges to increase the amount of recycled content in their product packaging. Straws, cotton swabs, plastic bags, and plastic cutlery are all examples of single-use plastics that countries are trying to outlaw while simultaneously mandating more recycled content. The petrochemical industry needs recycled plastics to keep up with the surging demand in the market.

As was previously discussed, mechanical recycling is insufficient to meet the market need for significant quantities of recycled plastics. That’s why chemical recycling has so much potential. Despite the industry’s early stage of development, it is expanding rapidly, with six commercial plants now in service and several more scheduled for commissioning in the coming years.

Potential revenue prospects of USD 120 billion in the United States and Canada alone are estimated by the Closed Loop report for technologies that filter, degrade, or transform waste plastics into like-new materials.

Video 01: Chemical recycling explained: an overview