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Evemination of crystallisation in biodiesel fuels prepared from hydrogenated vegetable oils in relation to their cold flow behaviour

Xue Tang 1Diana M. Camacho 1Kevin J. Roberts 1Xiaojun Lai 1Peter Hutchins 2Ken Lewtas 2

1. University of Leeds (SPEME), Leeds LS2-9JT, United Kingdom
2. Infineum UK Ltd, Abingdom OX13 6BB, United Kingdom

Abstract

Fuels derived from biomass lipids such as vegetable oils and animal fats have received increasing attention due to the economic and environmental issues. Different production conversion processes of triglycerides using different bio-feedstocks will yield fuels with different compositions and properties.  The most dominant of these fuels is biodiesel which is defined as Fatty Acid methyl Esters (FAME) obtained by transesterification process with an alcohol.

Recently, the hydrotreating of vegetables oils is used to produce “renewable diesel fuels” with a similar boiling point to petrodiesel to be used as a blend component for diesel fuels. Chemically hydrogenated vegetables oils (HVOs) are mixtures of hydrocarbons (especially normal and iso-paraffins) that can be produced by the catalytic hydrocracking of triglycerides having a very high cetane number. However, their cold flow properties are undesirable due to the high crystallisation temperatures of n-hexadecane and n-octadecane components, the mixtures’ main components. Therefore, a clear understanding of crystallisation process in HVOs is necessary in order to improve their cold flow behaviour.

This research aims to develop an understanding of the interplay between crystallisation kinetics and wax crystal structure and morphology from the solution phase in particular to address those issues related to practical fuel composition and to cold weather performance. Experiments are carried out on binary mixtures of n-hexadecane and n-octadecane and individual products crystallised from melt or solution.

The results obtained from Polythermal Differential Scanning Calorimetry (DSC) and turbidometric solutions characterisation applied to the analysis of the phase diagram of C16H24 and C18H38 mixtures and crystallisation kinetics. These phase diagrams together with kinetics of crystallisation data will be related to the structure of the crystals as characterised using in-situ XRD and to their phase composition as assessed by gas chromatography. 

 

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Related papers

Presentation: Poster at 15th Summer School on Crystal Growth - ISSCG-15, by Xue Tang
See On-line Journal of 15th Summer School on Crystal Growth - ISSCG-15

Submitted: 2013-06-05 15:44
Revised:   2013-06-05 16:07