Analysis of FAME in Diesel and Heating Oil

Abstract

Fossil fuel repository is decreasing worldwide very quickly and finding new sources becomes more and more difficult. Experts are expecting that the fossil fuel will end in a few decades. This is the reason for researchers to find alternatives. Many technical improvements have already been made for car engines and also many developments have been made in the area of fuel. FAME (fatty acid methyl esters) was found as an equivalent fuel to diesel. It is also known as “Biodiesel”. In Europe, it is mostly prepared from rape, palm or soy oil. In the process of biodiesel production, the glyceride bondages are broken and methyl esters of the long chained fatty acids are formed (FAME = fatty acid methyl ester). In recent years, car engines have been developed, which run with both fossil diesel and FAME. At a time of growing globalisation and increasing financial pressure on logistics and transport companies, cross contamination is an increasing issue. It needs extensive actions to clean a tank or a truck after having loaded FAME. Very often, traces of FAME can be found in other fuels. This was the reason, why a limit for FAME in Jet A-1 fuel needed to be defined and was set at 5 ppm (mg/kg) for aircrafts (Ministry of Defence (2008). Defence Standard 91-91 and Joint Inspection Group (2011). Aviation Fuel Quality Requirements for Jointly operated System (AFQRJOS) Bulletin No. 45). As diesel and FAME are used in one and the same engine, one would think that cross contamination is not critical. This is correct for car drivers. However, it is well known that FAME cannot be stored for more than a couple of years. The reason for this is it’s hydroscopic properties and it is also a very good alimentary for fungi. Pure fossil diesel can be stored for decades without any problems. However, when fossil diesel is stored over several years, containing small quantities of FAME, fungi growth starts quickly and the characteristics of the diesel can change drastically. First, the odour of such contaminated diesel changes, second, FAME causes sticky deposits with water on the bottom of the containers and tanks, and third, fungi which grow in the fuel cause filter clogging. A method was developed for sample preparation and quantification of FAME in diesel. There is a difficulty when diesel or heating oil is analysed using a gas chromatograph connected to a mass spectrometer (GC-MS). A diesel sample contains compounds, which evaporate at high temperature. The temperature limit for the analysis using GC-MS is given by the chromatographic column. As it was found that HP-Innowax1 shows the best