Since the petrochemical industry started in earnest after 1945, naphtha has been the preferred feedstock of crackers in Europe, where they are usually fed with a fraction from crude oil refining. In other parts of the world, where there is natural gas but no crude oil refineries, they are often fed ethane as the starting material.
As the industry has developed, some companies such as Dow have developed flexible crackers that can use either feedstock. This is advantageous for a company like Dow that is not backwards integrated into the oil or gas industry. Frequently, the decision on what to crack had depended on the balance between the cost of the feed, and the value of the slightly different slates of products that can easily be made from either source.
Dow is not saying much about the composition of the synthetic naphtha it is using, or how it is made. Esther Quintanilla, global & EMEAI mobility market segment leader at Dow Polyurethanes, explained that Dow’s flexible crackers allow them to explore new feed streams, and to incorporate new circular feedstocks. ‘It is a big thing to change the feedstock of crackers,’ she said. ‘We are working with the specification process to ensure that the circular naphtha is good to go into the cracker.’
After the naphtha is cracked and the components separated, she said, they are working with the specifications of the downstream C2 and C3 streams that can be used to make the polyol feedstocks ethylene and propylene oxide. This makes it a quite different approach to the company’s collaboration that makes Renuva polyols
‘The question we faced was how to produce a certified material that would help the automotive industry meet its requirements for more sustainable products,’ she said.
It is the first time that polyurethane raw materials have been made and commercialised from such raw materials.
‘Polyurethanes is the second business group in Dow to have the materials available for a market,’ she said. ‘But this is the first time that circular naphtha has been made from end-of-life waste generated by the mobility sector. We claim that this is circular naphtha from the mobility sector, and we really are able to prove it.’ Dow is using a mass balance approach.
‘The automotive industry is facing a very urgent need to become more sustainable,’ she added. ‘OEMs have more targets for using recycled materials Now they talk very specifically about the amount or the proportion in the RFQ.’
Dow chose to focus on polyurethane because it is a high-volume automotive polymer. ‘People talk about sustainability in the automotive sector,’ she said. ‘It is really the time to stop talking and start making it happen.’ She also said that customers were increasingly adding sustainability requirements in their request for quotation documents.
‘PU is the second biggest polymer used in automotive after polypropylene,’ she said. ‘PU makes up about 19% of the plastics used in vehicles, and polypropylene is about 33%. This is why the automotive industry wants circular products and circular PU. It can help them to comply with the end-of-life vehicle directive, and with their own sustainability goals.’
Because synthetic naphtha is at the bottom of the petrochemical production chart, it can be used to make both polyols and diisocyanates.
An additional benefit is that the proportion of intermediates made from synthetic naphtha can be tuned. ‘If you are a Tier and you want to disclose that you have 60, 70, 20 or 25% of the circular polyol in your polyurethane components, then you can fine tune it depending on how much circular naphtha is used to make the circular polyol,’ she said.
Dow claims that because it knows how much of the synthetic naptha goes into each downstream product, it can provide a paper trail of proof of its claims. Its customers can do the same, too. ‘This can help defend the position of polyurethane,’ Quintanilla said. The common criticism of the material is that its recycling is not as straightforward as it is for thermoplastics.
‘It is absolutely the moment to promote PU with this kind of solution,’ she said. ‘This is why we chose the Specflex C and Voranol C materials, because the recycled components can go into a system or into a component. There is a lot of flexibility… it is up to our customers. But it can be used in a lot of applications to show circularity.’
Automotive seat maker Adient and interiors component manufacturer Autoneum are the first automotive clients to test out the materials. While Adient will focus on seats Autoneum will focus on applications in acoustic and thermal management.
According to David Nash, Adient’s vice president for foam and trim, his company has, in collaboration with Dow, reached the significant milestone of a product design that creates a circular economy. ‘As an important building block on the way to further decarbonise vehicle production, the solution helps us to reduce fossil feedstocks by the re-integration of waste products without any compromise in quality and comfort,’ he said.
Quintanilla said that Dow is looking to to promote PU, and make it a greater part of the solution. ‘This is a start,’ she said. ‘We may not have the volume to replace everything yet, but we need to start somewhere. We need to prove to the whole industry that we are able to make it happen.
‘We are expecting a very big pull from the market. We are making growth plans for 2022, 2025 and 2030. Personally, I believe It would be awesome to have everything in the automotive market based on circular materials by 2030.’