Energy and chemicals group Sasol, which aims to become a leader in South Africa’s promising green hydrogen industry, reports that research advancements have been achieved that are supportive of the conversion of hydrogen and carbon dioxide (CO₂) into green jet fuel and chemicals.

Made in collaboration with the Catalysis Institute at the University of Cape Town (UCT), Sasol says the advancements relate to the use of a commercial iron catalyst, which is already produced cheaply and at large scale at Sasol’s Secunda plant, in Mpumalanga.

The iron catalyst can achieve CO₂ conversions greater than 40%, producing chemical feedstocks such as ethylene and light olefins, as well as significant quantities of kerosene-range hydrocarbons, or jet fuel.

The innovation is aligned with the JSE-listed group’s intention to leverage its existing Fischer Tropsch (FT) technology and skills to lead the development of South Africa’s green hydrogen economy.

Currently, the Secunda plant converts synthesis gas – a mixture of carbon monoxide and hydrogen, derived from coal gasification and supplemented by reformed natural gas – into 160 000 bbl/d of chemicals and fuels.

The group is, however, considering the introduction of green hydrogen – produced by using renewable electricity to split water into hydrogen and oxygen, using an electrolyser – into its FT processes to produce carbon-neutral jet fuel and other green products.

Sasol already produces a certified aviation fuel at Secunda from coal, but announced recently that it would partner with Enertrag, Afrox and Navitas in a project to produce sustainable aviation fuel from green hydrogen for export to Germany.

The project is expected to be submitted for participation in the German government’s H2Global auction programme in the coming few months.

Sasol and UCT, which have a long-standing collaboration on FT catalysts, have been working to find innovative ways to use the chemistry to convert CO₂ and hydrogen into a range of useful and green products.

“Conversion of green hydrogen together with CO₂, a process called CO₂ hydrogenation, is gaining significant interest worldwide and is a promising way to produce sustainable aviation fuels and chemicals which have a significantly lower carbon footprint,” Sasol Research & Technology VP for science research Dr Cathy Dwyer explains.

UCT’s Professor Michael Claeys says the university’s partnership with Sasol brings together Sasol’s established expertise around FT catalysis and synthesis gas conversion and UCT’s modelling and in-situ characterisation capabilities.

“In recent years, the university has also been working on CO₂ conversion technology and has built up extensive experience in CO₂ hydrogenation.”

There are two ways to convert CO₂ into useful products using the FT technology deployed by Sasol, with iron catalysts having been found to be advantageous when converting hydrogen and CO₂ directly over a single catalyst, using what is termed “tandem” catalysis.

In the indirect pathway, meanwhile, CO₂ and green hydrogen are first converted to synthesis gas either by co-electrolysis or over a catalyst. The synthesis gas is then reacted over a suitable FT catalyst, to produce hydrocarbons and water and Sasol’s suite of cobalt catalysts has been found to be efficient for the process.

The latest iron catalyst development is described as a significant step towards the implementation of CO₂ hydrogenation technology in South Africa.