Page 129 - CW E-Magazine (9-1-2024)

Point of View

Reliance pioneers production of chemically recycled

polymers in India

Last week, Reliance Industries Ltd. (RIL), India’s largest petrochemicals producer, announced that it has become the first Indian
company to chemically recycle mixed plastic waste to produce polyolefins – polyethylene (PE) and polypropylene (PP) – at its refinery and
petrochemicals site in Jamnagar (Gujarat). The first batch of these polymers – under the brand names CircuRepol (PP) and CircuRelene (PE)
were shipped recently.

This is a milestone in the development of the Indian plastics industry and it was appropriate it came from RIL. After all, the company
was single-handedly responsible to taking polymer production here to world-scale and stimulate demand to growth rates unheard of earlier.

The effort is also in sync with measures other petrochemical producers globally are taking.

What is chemical recycling?
Chemical recycling represents an attempt to recapture value for a material that would otherwise have none, and is one way to
re-attain polymer properties identical to that of virgin material. Most importantly, it enables the recycling of mixed polymer waste streams,
as well as condensation and addition polymers. Theoretically at least, chemical recycling could be done with ‘zero’ new carbon drawn
from fossil fuels (save that used in the process of conversion) – but practically speaking that is still a long way off!

Chemical recycling processes vary, but typically follow the following template: Plastic waste is chopped up and treated with some
combination of water, heat, pressure, enzymes and catalysts, breaking the resin down into its constituent parts. These can then be
repolymerised to yield virgin-quality resins, or used as fuel or as raw materials for other products.

Chemical recycling comprises three mechanisms by which the polymer is: purified from plastics without changing its molecular
structure; depolymerised into its monomer building blocks, which in turn can be repolymerised; or converted into chemical building blocks,
which are then used to produce new polymers. Based on these mechanisms the main chemical recycling technologies are solvent-based
technologies including dissolution and solvolysis; thermochemical technologies including pyrolysis and gasification; and enzymolysis.

In the most widely practiced form of chemical recycling – and the one deemed most scalable – mixed plastic waste is chemically
converted into pyrolysis oil (along with some light gases and char) by a thermochemical treatment that typically involves heating the
plastic waste in the absence of oxygen. This pyrolysis oil, after treatment by fractional distillation to get rid of impurities, is then co-fed
into an operating steam cracker running on hydrocarbon feedstock (e.g., naphtha), to yield olefins (and other products). This is the route
that RIL has taken for its circular polymers.

Since the blend ratio of pyrolysis oil is still small in all operations (typically not more than 5-10% of the total feed to the cracker) –
for technical and commercial reasons – an accounting trick, known as mass balance (MB), is used to assign a ‘circular’ tag to the same
portion of the olefins and polyolefins produced. The greater the proportion of the pyrolysis oil in the cracker feed, the greater the proportion
of olefins and polyolefins assigned the circular tag.

The MB approach is a well-established practice, and there are independent certification agencies, of which International Sustainability &
Carbon Certification Plus (ISCC+) is most widely used, to vouch for the integrity of the practice. There are even some attempts to use
block chain technologies to authenticate each step of the conversion (from waste plastic to the circular polymer), and provide assurance
to the final consumer (which could be a consumer-facing company, for instance) that the claims on circularity are justified.

Chemical recycling vis-à-vis mechanical recycling
The advantage of chemical recycling is that it produces polymers chemically identical to those from traditional sources (such as
cracking naphtha, ethane or mixed feeds). This means they have identical properties and performance in the intended application, which
is particularly important when it comes to food contact or medical uses. The other benefit of the sameness is that plastic processors need
to make no change to their operations, which is comforting to them.

Mechanically recycled polymers do not have these virtues. Having gone through thermal stresses of processing once, recycled polymers

Chemical Weekly January 9, 2024 129

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