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Diesel Blend with Cyclic Oxygenate Cuts Soot by 50%

A doctoral candidate at Technische Universiteit Eindhoven (TU/e) has developed a new blend of diesel using cyclohexanone as a low cetane oxygenate. (Earlier post.) Cylcohexanone ((CH2)5CO) is also a precursor to nylon. The new fuel, named Cyclox, enables enhanced mixing as a result of both an extended ignition delay and longer FLOL (flame lift-off length)—and as a result, produces fewer soot particles.

During tests conducted in an idling passenger car, a blend of 10:90 (cyclohexanone:ordinary diesel), resulted in a 50% reduction in soot emissions. The university has applied for an international patent on Cyclox.

The research conducted by ir. Michael Boot also showed that cyclohexanone can be made from lignin. This substance is released in great quantities as a waste product in the paper industry, among others. The Eindhoven researcher wants to try and develop an industrial process for making cyclohexanone from waste lignin on a large scale and at low cost.

Cyclic oxygenates are abundant in nature. Cellulose, the most common organic compound on earth, is the best-known example. Although it is not trivial, liquid cyclic oxygenates can be made from lignocellulosic biomass.

—Boot (2009)

Together with three Departments and several companies he has submitted a project proposal for this with Agentschap NL; the intention is not only to make Cyclox with the lignin-derived cyclohexanone, but also “green” nylon. Cyclohexanone is also the main raw material of nylon.

PFAMEN. Boot has also devised a new kind of diesel injector tip, the PFAMEN (Porous Fuel Air Mixing Enhancing Nozzle). Normally an injector tip has a limited number of holes; Boot proposed a porous nozzle tip with pore diameters between 1 and 50 \gmm instead. The small pore diameters result in fine atomization of the charge. The configuration of the nozzle can be chosen such that the whole cylinder can be filled with fine droplets (i.e., spray angle nearly 180\mD).

A prototype of the device has already carried out half a million injections successfully. The PFAMEN also works at a lower pressure than current diesel injectors, further reducing fuel consumption. The fuel circuit, which is the most expensive part of the engine, can also be made much less expensively.

Michael Boot conducted his research with the Combustion Technology group of the Department of Mechanical Engineering. His research was financed by STW technology foundation and DAF Trucks.


  • Michael Boot et al. (2009) Cyclic Oxygenates: A New Class of Second-Generation Biofuels for Diesel Engines? Energy Fuels 23 (4), pp 1808–1817 doi: 10.1021/ef800363

  • Michael Boot et al. (2009) Porous Fuel Air Mixing Enhancing Nozzle (PFAMEN) (SAE 2009-24-0028)



This could further improve future diesel engine performance while lowering air pollution. How long will it take to be incorporated, if ever?


How much does Cyclohexanone cost? And more importantly, does bio-derived Cyclohexanone deprive third-world people the right to Leisurewear™?


Maybe we could recycle women's nylon underwear.

Tim Duncan

Another fuel idea, ho hum. I am more interested in low pressure high atomization fuel injection. If it works for diesel, it could be even more useful in GDI, as pumps for gas will always lag behind in pressure capability.

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