Circularity in Plastic Value Chains
Plastic pyrolysis oils as feedstock for steam crackers
Special Focus: Sustainability and the Energy Transition
In a recent two-part article published in Hydrocarbon Processing, authors Clara Delhomme-Neudecker, Nicole Schödel, Ákos Tóta, and Gunther Schmidt go over the pillars of knowledge required for this task. In the first article, detailed analytics know-how and pilot cracking know-how are covered; in the second article, the spotlight is on process design know-how.
Plastic Waste - a huge environmental challenge
Plastic waste is a huge challenge with far-reaching environmental consequences. Today, the World Economic Council estimates that less than 10 percent of plastic waste globally is recycled. Obviously, that number needs to go up if the world wants to get serious about implementing a circular economy.
The most common method of recycling plastic is through mechanical means. Here, plastic is sorted by type, shredded into small pieces, and then reprocessed into new products, like packaging and toys. Polyethylene terephthalate (PET) and polypropylene (PP) are two types of plastic that are especially well suited for mechanical recycling. However, there are many other types of plastics, including mixed plastic wastes, that are not. This is where chemical recycling enters the picture.
Feedstock for steam crackers
With chemical recycling, the plastic waste is broken down into molecules that can then be reused as raw materials for the plastic industry or for the production of other chemicals, and a key method is through pyrolysis. The result of this thermal decomposition process is a liquid hydrocarbon mixture called pyrolysis oil, or pyoil, which can then be used as a circular feedstock for steam crackers. The resulting chemicals from the steam cracking process, first and foremost ethylene, are used to create new plastics. These recycled plastics have the same high-quality properties as virgin plastics and are environmentally friendly, because they reduce the dependence on fossil feedstocks and reduce the amount of plastic waste disposed in landfills or send to waste incineration.
Know-how in three areas essential.
A key challenge is that ethylene producers need to determine which processing methods are most appropriate for their pyoils – and the options are extensive. Help is available: the Linde Engineering Sustainable Hydrocarbons team supports ethylene producers in evaluating the necessary steps for using pyoils as a cracker feedstock.
