A stepping stone to bio-plastics?
By Callum Colford, Sarah Trinder, Abdulaziz Ehtaiba, Luke Milner
Strong bio-ethylene interest from the polyethylene market
Significant premiums hinder bio-butadiene market
The olefins sector has seen strong downstream interest in bio-products, with bio-olefins a key link in the chain from bio-feedstocks through to end-products including plastics and synthetic rubber.
Production methods in the sector vary from “drop-in” production, which produces bio-based material from a mass-balanced feedstock via a steam cracker, to newer production methods which use products such as ethanol to produce bio-based ethylene via independent production methods.
Bio-ethylene has found strong interest from downstream sectors, particularly from polyethylene applications looking to find a green solution to production methods, driven by increasing consumer interest in environmentally friendly alternatives.
Bio-ethylene, or “green ethylene”, can be produced from cracking bio-naphtha and also from the production of ethylene from ethanol.
Brazilian producer Braskem uses ethanol from sugarcane which is then processed into bio-ethylene used in the production of bio-polyethylene and ethylene vinyl acetate (EVA)
Braskem started the first sugarcane-derived ethanol-to-ethylene plant in 2010 at Rio Grande do Sul in the south of Brazil, using the bio-ethylene produced there to manufacture polyethylene. The company is expanding its green ethylene production capacity at the Rio Grande site by 60,000 mt to 260,000 mt/year with completion projected to be in the fourth quarter of 2022.
In recent years production has been gaining traction in the European market but cost remains a barrier for those considering bio-ethylene purchases, given the sizeable premium to traditional ethylene.
“There are inquiries, but the price tag is significant. There are quite a few inquiries, but they’re not interested when they see the price tag,” one European ethylene producer said.
However, in the past three years producers have continued to develop options, with both Dow and INEOS partnering with UPM Biofuels to use the latter’s bio-naphtha as a feedstock to produce renewable plastics.
In 2018 Clariant signed a deal to use Neste’s bio-ethylene (and bio-propylene) in its adhesives, plastics and coatings, and LyondellBasell followed suit in 2019, partnering with Neste to secure feedstocks for its bio-based plastic brands – Circulen and Circulen Plus.
Although the development of bio-propylene has been slower than the development of bio-ethylene, a proliferation of production methods has come to the fore in the past two years.
As companies look to on-purpose bio-propylene production to ensure the development of bio-polypropylene production, the industry is looking for alternative production routes to “drop in” cracker bio-feedstocks.
In October 2019 Austrian petrochemical and plastics producer Borealis announced plans for the first ever use of renewable propane dehydrogenation on an industrial scale for on-purpose bio-propylene to produce polypropylene with measurable bio-based content with ISCC Plus certification.
Finland’s Neste supplies Borealis with renewable propane produced in Rotterdam to feed the Austrian plastic producer’s PDH unit in Kallo, Belgium.
Production of bio-based PP, the end product of the process, began in December 2019, with bio-propylene from the Kallo PDH unit supplying both Borealis’ Kallo and Beringen production sites.
Japan’s Mitsui Chemicals is also looking to produce bio-propylene in order to produce bio-PP but via the dehydration of bio-isopropanol that comes from raw biomass materials, although the company has said that commercial production will not start until 2024 at the earliest. “There are significant hurdles associated with manufacturing polypropylene from biomass materials and the technology has yet to be demonstrated on an industrial level,” the company said in its 2020 ESG report.
Bio-butadiene has also seen an increase in interest in recent years, both from drop-in production methods produced via a steam cracker, and novel production methods being trialed.
French tire producer Michelin is building a pilot bio-butadiene plant as part of its “biobutterfly” project, which will produce bio-butadiene to be used in the production of synthetic rubber for tires. The project uses ethanol produced from a range of biomass such as second-generation ethanol made from forestry and agricultural residues like wood chips, rice husks and corn stalks.
Other companies such as Trinseo are carrying out feasibility studies into construction of a pilot plant with Russian company ETB for bio-butadiene production. The study — expected to be completed by the end of 2021 — has a target to produce butadiene with a purification rate for the pilot plant of 99.7%, in line with fossil-based butadiene purification rates, using bio-based ethanol as a feedstock.
Similarly, Synthos has started co-operation with Lummus Green Circle to launch a feasibility study into a bio-butadiene plant with a production capacity of 20,000 mt/year, using ethanol.
While Michelin has taken a novel approach to bio-butadiene production, other companies such as Versalis produce via the drop-in method, using first- and second-generation bio-naphtha produced at two Eni bio-refineries in Italy to then produce mass-balanced butadiene.
Other major producers such as TotalEnergies also utilize this method of production via a mass-balance method, which uses existing production infrastructure rather than requiring new production methods.
This is currently the primary method of production and many market observers expect it will remain predominant for the next decade or so, until alternative methods are more thoroughly proven.
“Bio-based [alternative] projects are going to be very expensive with premiums of over $1,000/mt but can this be justified? If you are getting premiums at three times normal prices, then you can justify building the plants, but the plants are not ready yet and consumer demand at these levels is uncertain,” a major European petrochemical producer said.
Major interest in bio-butadiene applications comes from the tire sector, following moves by companies to commit to using greater proportions of sustainable materials. For example, the two largest tire manufacturers globally, Bridgestone and Michelin, have stated that by 2050, their tires will be made entirely from renewable, recycled, or bio-sourced sustainable materials, with company sources saying a mixture of bio-based material and chemical recycling would be necessary to reach the targets.