The_Catalyst_Review_April_2023 - 19

Industry Perspective (cont'd from page 3)
Steps in the Right Direction
Honeywell UOP/ENI and Topsoe have developed eco-hydrotreating technologies to
turn these vegetable oils and fatty acids into renewable (green) diesel and sustainable
jet fuel that can be mixed with crude-derived diesel and jet fuel (the SAF from these
feedstocks generally has no aromatic content and hence must be mixed with fossilbased
jet fuel). Axens and Sulzer also have similar technologies.
Existing hydrotreating units can be revamped to process renewable vegetable oil/fatty
acid feedstocks in higher proportions than the 5% to 7% level, in some cases, even in a
single reactor.
It should be noted that these feedstocks are currently low-volume and expensive in
comparison with fossil-derived middle distillates, but Neste has positioned itself as a
leading producer of sustainable aviation fuel in partnership with selected airlines. Shell,
TotalEnergies and Marathon have all announced plans to reconfigure at least one of
their refineries to produce bio- and sustainable fuels, especially SAF.
Ethanol is dehydrated,
polymerized and
saturated to make a
fuel that meets jet fuel
standards.
An alternative route to SAF uses biomass-derived ethanol, which has an economic advantage as the sugar or corn-starch-based
ethanol feedstock is much cheaper than the tri-glyceride feedstocks. Several technologies using this ethanol-based route to SAF
are being developed and commercialized. Ethanol is dehydrated, polymerized and saturated to make a fuel that meets jet fuel
standards.
Hydrogen production in refineries is generally a by-product of processes such as catalytic reforming and ethylene cracking or by
steam-methane reforming of natural gas or light hydrocarbons and is termed grey hydrogen. Grey hydrogen is seen to be better
than hydrogen derived from coal (brown hydrogen) but is not deemed to be a sustainable source of hydrogen. Green hydrogen
is generally produced by splitting hydrogen from water using electrolysis. To ensure sustainable aviation fuel and diesel is 100%
renewable, the hydrogen used for hydrotreating should be green hydrogen where the electricity used by the electrolyzers is also
sourced from renewable energy.
Benchmarks of the Renewable Economy
The impact of the renewable economy on electricity generation and distribution networks will be massive. The traditional thinking
is that electricity generation needs to be on a large or massive scale. An alternative paradigm is to connect a (very) large number of
micro-generation installations. This solution will be cheaper and more sustainable, and will work out to be more responsive in the
short and the long term. The most potential lies in expanding solar and wind generation into domestic, schools, commercial, farm
and industrial environments - installing 150% to 200% more than own-use requirements and exporting excess electricity to the grid.
This will reduce transmission losses and alleviate the pressure on major distribution systems.
Refineries generate electricity mainly from cogen units or excess steam, primarily from fossil fuels. However, refineries can also
generate the electricity required for the electrolysis process by using renewable energy, i.e., solar and/or wind. There is a lot of
elevated real-estate in refineries that could be suitable for medium-sized wind turbines, such as structures that support reactors,
columns, vessels, heat exchangers, fin-fans, piping, etc. Horizontal-axis wind turbines are, for obvious reasons, probably not suitable,
but new-generation vertical-axis wind turbines may become a viable option in the near future.
So, as the renewable economy emerges, the only certainty is that refineries will see growing pressure to adapt to the new
environment (pun intended).
Your Author
Shaun Dyke, of PetroQuantum, is a very experienced chemical engineer who has worked in the refining
and petrochemical industries for more than 40 years, in a number of technical, managerial, governance and
consulting roles, all over the world. He lives in and works from New Zealand and writes in his spare time.
He has a BSc (First Class Honours) in Chemistry from Massey University, New Zealand. He can be reached
at shaun.dyke@petroquantum.co.nz.
Resources
1. Kalnes T, et al. Green diesel production by hydrorefining renewable feedstocks. https://silo.tips/download/approximately-50-of-globally.
2. Rasmussen H. Renewable diesel and jet fuel. https://www.researchgate.net/publication/321961317_Renewable_Diesel_and_Jet_Fuels.
3. Jenkins S. SAF production expands for a low-carbon future. https://www.chemengonline.com/saf-production-expands-for-a-low-carbon-future/?printmode=1.
The Catalyst Review
April 2023
19

https://www.silo.tips/download/approximately-50-of-globally https://www.researchgate.net/publication/321961317_Renewable_Diesel_and_Jet_Fuels https://www.chemengonline.com/saf-production-expands-for-a-low-carbon-future/?printmode=1

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