Fuels & Lubricants Magazine

GREEN CORNER
gases is needed. The relative relation and extent of the
side reactions are calculated from the distribution of
secondary products: carbon monoxide, carbon dioxide
and methane.
CO 2
+ H 2
—> CH 4
+ H 2
O (2)
Hydrogen consumption during the decarboxylation
or hydrodeoxygenation reaction has a major influence
on product yield distribution, inhibition of catalysts, gas
composition and heat balance.
If all triglycerides are reacted by decarboxylation,
seven moles of hydrogen will be consumed in contrast
to sixteen moles of hydrogen to be consumed if triglycerides
are converted by HDO mechanism, ie 63% lower
hydrogen consumption. However, if all the carbon dioxide
obtained is converted to carbon monoxide and then
into methane, it will consume nineteen tons of hydrogen
by decarboxylation, ie the consumption of hydrogen is
19% higher [11].
Therefore, the ratio of decarboxylation and hydrodeoxydation
reaction mechanisms should be 65/35. The
favourable relationship between the reaction mechanisms
can be monitored by the analysis of the relative
relation between n-C17 and n-C18 by the simulated
distillation method. This relationship depends on the
type of catalyst, the process conditions and the type of
renewable feedstock.
CONCLUSION
The key parameters that show the quality of used cooking
oil or waste animal fat for the hydrotreating process
are the total acidity, water content, metal content and
free fatty acids content.
The used cooking oil is more suitable feedstock than
animal fat due to lower acid number, kinematic viscosity
and significantly lower metal content. Such properties
make used cooking oil more suitable for direct coprocessing
in refinery units by known conversion processes.
The reactions of UCO hydrotreating are exothermic
so during co-processing increasing of temperature in the
catalyst layer should be noticed which could have the
impact on duration of the catalyst.
The key barrier for the independent processing of
UCO and animal fats in refinery units is the limit availability
of the feedstock. Also, for continuous co-processing,
it is recommended to upgrade the hydrodesulfurization
unit with isomerisation unit to have a possibility
to convert the n-paraffins partly into iso-paraffins to
improve low-temperature properties of the obtained
diesel fuel.
Hydrotreating of used cooking oil and animal fats for
the production of hydrotreated vegetable oil used as
a fuel in transport is a promising technology that will
inevitably develop in the following years in European
Union countries or in oil companies in order to replace
part fossil fuels with renewable fuels in economically and
environmentally effective way.
LITERATURE
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TXT/PDF/?uri=CELEX:32015L1513&from=HR (access:
June, 22th 2018)
[2] M. Crocker, Thermochemical conversion of biomass
to liquid fuels and chemicals, Royal Society of Chemistry,
UK, 2010, p. 1-25.
[3] D. Sperling, D. Gordon, Two Billion Cars: Driving Toward
Sustainability, Oxford University Press, 2009, p. 6-7.
[4] M. Guo, W. Song, J. Buhain, Bioenergy and biofuels:
History, status, and perspective, Renew. Sust. Energ.
Rev. 42 (2015) 712-725.
[5] L. Zhang, G. Hu, Supply chain design and operational
planning models for biomass to drop-in fuel production,
Biomass Bioenerg 58 (2013) 238-250.
[6] M. F. Ali, M. E. Ali Bassam, J. G. Speight, Handbook
of Industrial Chemistry, Organic Chemicals, McGraw-
Hill, New York, 2014, p. 528-537.
[7] Izvješće o posebnim kategorijama otpada za 2016.
godinu, Hrvatska agencija za okoliš i prirodu, travanj
2018. p. 7 - 9
[8] S. J. Miller, Production of Biofuels and Biolubricants
From a Common Feedstock, US Patent Publication No.
0084026, 2009, p. 1-2.
[9] M. J. McCall; A. Anumakonda, A. Bhattacharyya, J.
Kocal, Feed-Flexible Processing of Oil-Rich Crops to
Jet Fuel, AIChE Meeting, Chicago, 2008.
[10] B. Donnis; R. G. Egeberg, P. Blom, K. G. Knudsen,
Hydroprocessing of Bio-Oils and Oxygenates to Hydrocarbons,
Understanding the Reaction Routes, Topics in
Catalysis 52 (3) (2009) 229-240.
[11] R. G. Egeberg, N. H. Michaelsen, L. Skyum, Novel
hydrotreating technology for production of green diesel,
Haldor Topsoe, 2010, 6-9.
28 Fuels&Lubricants No. 3 OCTOBER 2018