A Systemic Approach To Understand Relationship Between Compositions Of Gtl Derived Synthetic Fuels And Their Properties
Authors: Elbashir Nimir 
Published: November 2013

Gas-To-Liquids technology is increasingly becoming an attractive source of ultra clean fuels, such as synthetic jet fuel. However, these synthetic fuels still face challenges in acquiring certification based on their properties. The focus of our current activities revolve around the experimental measurement of physical properties of fuel blends as per the aviation industries and ASTM guidelines [1], along with statistical analysis and visualization to find optimum fuel blend compositions that meet the required standards for certification. Through a series of distinct phases and with local funding from the Qatar National Research Fund (QNRF) and Qatar Science and Technology Park (QSTP), our research team has built an extensive Fuel Characterization Laboratory at Texas A&M Qatar in order to generate significant amounts of reliable data that meet industrial standards. Our methodology is to systematically generate several series of Synthetic Paraffinic Kerosene (SPK) fuel blends and to test them for their physical properties, such as density, viscosity, heat content, freezing point and flash point, following a strict safety and quality management system. In the first testing campaign the fuel blends were made from specific classes of typical GTL products (normal-, iso- and cyclo-paraffins) where the amount of each component was varied [2]. The analysis of the data generated (Figure 1) has enabled us to map how the hydrocarbon structure of a given SPK fuel blend influences its physical properties [2]. In a recent follow-up study we have also examined and mapped the influence of a fourth component, the aromatic building block, on the fuel blend properties. Aromatics improve the fuel density, which is one of the major hurdles in certifying these synthetic fuels. Separate studies also show that aromatics improve fuel-elastomer compatibility and lubricity [3]. In these first two campaigns the blends were limited in carbon number to C10 n- & cyclo- and C12 iso- paraffins, and the C7 mono-aromatic, toluene in order to study the effects of hydrocarbon structure. To improve on the model we are extending our map to study a wider range of carbon numbers. Blends in our current study are formulated from C7 to C14 hydrocarbons, which mimic the conventional jet fuel range. It is expected that these results will improve our understanding the influence of carbon chain length on the fuel properties, which have been expanded on to investigate known problematic SPK properties such as lubricity and electrical conductivity. We will report on our findings from our latest studies including the results of the aromatics campaign (using mono- as well as di-aromatics) and the statistical analysis of these data. The results from all phases are integrated into the multidimensional visualization model that correlates the properties and compositions of fuel blends. A completed model will be a useful predictive tool to help optimize the new generation of synthetic Jet fuels. References: [1] ASTM Standard D1655, 2010, DOI: 10.1520/D1655. [2] Bohra M., et al.(2012) QF-ARF, Vol. 2012, EEPS4,. [3] Orillano, M., et al. (2012) QF-ARF Vol. 2012, EEOS2.