Platinum is required across all major sustainable aviation fuel (SAF) production pathways, including power-to liquid (PtL), which uses the Fischer Tropsch process (FT), as well as the FT process itself, and while current platinum demand from SAF is modest, it is expected to grow significantly in the long term, industry body the World Platinum Investment Council points out. 

The council expects yearly SAF capacity additions to increase eight-fold from about two-million tonnes in 2024 to about 16-million tonnes by 2050, while platinum demand from SAF production is expected to increase from negligible volumes to about 260 00 oz/y by 2050.

“This platinum demand growth will be incremental overall, mitigating the expected decrease in petroleum platinum demand as global markets continue to make their energy transition from 2030 to 2050,” the council explains.

The International Air Transport Association estimates that SAF could contribute about 65% of the reduction in emissions needed by aviation to reach net-zero emissions by 2050.

Unlike petroleum-based kerosene, SAF is produced from sustainable, non-petroleum feedstocks such as waste oils, agricultural residues and municipal solid waste, or via synthetic e-fuels combining renewable electricity with captured CO₂, the council explains.

Originally developed by German chemists Franz Fischer and Hans Tropsch, this year marks 100 years since the FT process was developed.

Their research demonstrated that a mixture of the gases carbon monoxide and hydrogen could be transformed over suitable catalysts into liquid and solid hydrocarbons. Today, FT is used in myriad industrial applications, the council outlines.

PtL is a synthetic jet fuel produced using renewable electricity, with water and CO₂ serving as the primary inputs.

To create a climate-neutral carbon feedstock, green hydrogen and captured CO₂ (from the atmosphere or industrial sources) are used.

These components are then combined through FT synthesis to form liquid hydrocarbons, which are subsequently refined into a kerosene-equivalent fuel, the council adds.

In the FT SAF production pathway, solid materials such as biomass are first converted into synthetic gas (syngas). This syngas is then processed through FT synthesis into liquid wax. FT has significant scalability potential for SAF production as it can use a range of feedstocks, including waste materials that would otherwise be discarded.

This makes it a strong candidate for commercial-scale SAF production, although supportive policies and regulatory frameworks are needed to accelerate its deployment.

PLATINUM’S ROLE

The council highlights that platinum plays an important supporting role in certain types of FT synthesis. Iron catalysts dominate biomass FT and do not use platinum.

However, cobalt catalysts are preferred in PtL FT and these use platinum as a promoter. Even at very low concentrations, platinum improves cobalt catalyst reduction, stability and dispersion, resulting in higher efficiency and longer lifetimes, the council posits.

It adds that platinum has a significant role in isomerisation, which is needed in both the FT and the PtL FT SAF production pathways, where it functions as a catalyst to transform straight-chain hydrocarbons into branched isomers with better cold-flow properties.

“Without this step, SAF would fail to meet the strict freezing point requirements necessary for safe, high-altitude flight,” the council avers.