BIO-BASED NAPHTHA: Alternatives to fossil-based naphtha needed to meet sustainability goals

By PIE correspondent

Renewable alternatives to fossil-based naphtha will be needed to meet sustainability goals, says nova-Institute (Hürth, Germany; www.nova-institute.eu) in a new report. Key routes to the production of bio-based naphtha include the co-processing of bio-based feedstocks, the hydrotreating of vegetable oil, and the pyrolysis of plastics and tyres, says the report, entitled Alternative naphtha – technologies and market, status and outlook.

The “alternative naphtha” concept makes use of existing refinery, steam cracking, and chemical industry infrastructure, with a proportion of fossil-based feedstocks – crude oil or fossil-based naphtha – replaced by renewable alternatives derived from the three sources of renewable carbon: CO₂, biomass, and recycling.

This approach allows for the volume of renewable carbon substituting for fossil carbon to be increased over time, nova-Institute says. The renewable carbon input can be attributed to one or more output chemicals.

Related: Growing calls for EU policy to incentivise use of sustainable carbon feedstocks

In Europe and Asia, fossil-based light naphtha is a key feedstock for steam cracking processes to produce olefins and polymers such as polypropylene and polyethylene. Light naphtha is also converted to reformate for the production of aromatics and polymers such as polystyrene and polyamide.

Steam cracking operations vary around the world in terms of acceptance of feedstocks, and in the US and Middle East they are set up for lighter ethylene or gas-based feedstocks and are not necessarily suitable for processing bio-based naphtha, notes the report.

With co-processing, bio-based feedstocks – typically first-generation such as rapeseed oil, palm oil, sunflower oil, and soybean oil – are fed into existing refinery processes alongside fossil feedstocks.

The process of hydrotreating or hydrogenating vegetable oil (HVO) or hydrogenated esters and fatty acids (HEFA) has been developed primarily to produce bio-based diesel and synthetic aviation fuel, the report notes. Feedstocks also include waste oils such as used cooking oil and by-products from the processing of palm oil as well as tall oil, a by-product of the wood pulp and paper industry.

In addition to producing bio-based diesel and synthetic aviation fuel, bio-based naphtha is produced at levels of up to about 10% of total output. Bio-based naphtha and, dependent on the configuration of the steam cracker, renewable (bio-based) diesel from the HVO/HEFA process can replace fossil-based light naphtha as a steam cracker feedstock, according to nova. 

Worldwide production via HVO/HEFA was estimated at 18.2 mn t in 2023, with planned projects taking capacity to close to 40 mn t by 2026.

In 2023, a total of approximately 1.15 mn t of renewable naphtha and renewable diesel were estimated to be used as steam-cracker feedstock from which renewable attributed products were made. Based on currently known projects, the report said production for the chemical industry is expected to rise to approximately 1.6 mn t by 2026.

The production of pyrolysis oil from plastics and tyres has grown significantly in the past 2-3 years because it offers circularity for plastics containing waste that is often difficult to recycle by mechanical means.

Proposed, new EU legislation sets ambitious targets for recycled content in plastic packaging materials. Pyrolysis offers advantages in achieving the quality standards that packaging materials in contact-sensitive applications have to achieve, according to nova.

Related: Zero Waste Europe study critical of pyrolysis in Green Deal context

While legislation has not officially been introduced into EU law yet, nova Institute said it can be expected that pyrolysis and other chemical recycling technologies will play a significant role in achieving more ambitious reclaim targets. The global capacity to produce pyrolysis oil could exceed 1.5 mn t/y by 2026 if current projects with refinery and chemical industry offtakers continue as planned, according to the report.

Another possible route to alternative naphtha given in the nova report is the gasification of biogenic waste or plastics-containing waste to produce syngas, a mixture of carbon dioxide and hydrogen. The syngas is converted into a mixture of renewable naphtha, diesel, and sustainable aviation fuel via the Fischer-Tropsch process. While production from plastics is a possible route, activity to produce fuels and chemicals in this way is very limited, with the gasification of wood-waste biomass the focus for this technology.

The production of naphtha from carbon capture also relies on the Fischer-Tropsch process. CO₂ can be sourced and captured from industrial emission sources, from biogenic waste gas streams, or extracted from the air using direct air capture systems.

Related: EU Commission rep discusses decarbonisation at annual EuPC conference

Most projects for fuels via carbon capture and the associated production of naphtha are not expected to be realised until after 2026, the report noted. They are currently foreseen for the period 2026-2030, when the resulting CO₂-based hydrocarbon capacity could increase to close to 800,000 t/y worldwide.

“Alcohol to jet” chemical process technologies could also contribute some further co-product naphtha to chemical processing. Here, alcohols such as methanol, ethanol, and isobutanol could be “upgraded” to produce synthetic kerosene, the report said.