5 Analytical Instrumentation
samples received as unknowns (Tables 2.). The samples were prepared by mixing 10 ml of fuel with 10 ml of MaxiLight+ cocktail and analysed for 7h.
Conclusion
Our aim was to develop a novel, easy-to-use, direct LSC measurement for determining the bio-% of biofuels. The Hidex biofuel method was tested with different types of fuels whose bio percentage varied between 1% and 100%. The method is based on an algorithm which is derived from background and effi ciency quench curves with chemical and colour quenchers. The algorithm uses TDCR and external standard quench parameters for fi nding the background and counting effi ciency of unknown samples. A fuel-specifi c background sample is not required. The Hidex biofuel method expands the applicability of direct LSC. The results presented here show that it is suitable for a wide range of fuel types and their blends. as well as for coloured fuels. The bio percentages determined with the Hidex biofuel method were very well in-line with the corresponding AMS results.
Summary Background and effi ciency quench curve samples for the calibration of Hidex Biofuel Method
• Direct in-house measurement of bio-% • No need for a fuel specifi c background sample • Minimal sample preparation
Table 2. Biofuel comparison study with AMS and Hidex biofuel method. All samples were received as unknowns. *The specifi c activity of very old wood- based material is higher than 13.56 DPM/g used in the calculation. **If fossil methanol is used in the production of FAME, the bio-% is 93-95% of expected.
Composition 100% HVO 100% HVO 100% HVO 100% HVO
100% HVO (woody biomass) * 70% diesel 7% FAME, 23% HVO** 70% diesel 7% FAME, 23% HVO** 70% diesel 15% FAME, 15% HVO** 100% diesel 100% FAME**
100% GTL (fossil)
90% diesel, 10% HVO 95% diesel, 5% HVO 100% bio-naptha
80% petrol, 10% ethanol, 10% bionaptha
and the carbon content of the biofuel is determined for the bio-% calculation. Very volatile samples (for example, naphtha and gasoline) can be diffi cult to weigh. To ease the sample preparation, such samples can be cooled before weighing. Dilution is recommended for intense coloured biofuel samples. Quenching can be reduced using less sample. Sample to cocktail ratio can be reduced from 10 + 10 ml to 5 + 15 ml, or experimentally even lower. Samples are always prepared in the same type of vials as used in the quench curve calibration.
LSC measurement
Long measurement times (5-7 hours) are recommended for low activity biofuel samples, i.e. for fossil and mid to low bio-% samples. Shorter measurement time (for example 1-2 hours) can be used for scanning purposes and for high bio-%
Results
Hidex biofuel method has been tested with various types of fuels and their blends. Here we share the results from in-house prepared HVO-diesel samples (Table 1.) and from biofuel
AMS University 101.2 ± 1.2 100.9 ± 1.2 100.7 ± 1.2 100.1 ± 1.2 111.0 ± 1.4 25.3 ± 0.3 28.6 ± 0.4 29.8 ± 0.4 0
95.4 ± 1.2 0
LSC Hidex 100.2 ± 0.8 99.6 ± 0.8 100.4 ± 0.8 103.1 ± 1.0 106.4 ± 0.7 26.7 ± 0.9 25.7 ± 0.9 30.1 ± 0.4 0.1 ± 0.3 95.6 ± 0.9 -0.1 ± 0.3 9.8 ± 0.3 5.0 ± 0.3 96.6 ± 0.9 17.1 ± 0.4
samples. The LSC biofuel protocol will indicate with red fl ags if some of the samples is out of the optimised range of the algorithm (for example, too low quench parameter QPE and/ or counting effi ciency) and requires more dilution. All results are calculated in the LSC biofuel protocol. The counts are collected from optimised luminescence free triple coincidence ROI. Background count rate and counting effi ciency are predicted using the algorithm. The fuel mass and the carbon content are entered to the biofuel protocol before or after the measurement. Results are reported as mass bio-% or pMC depending on the carbon content used.
• Suitable for wide variety of fuel types and their blends with colour
• No luminescence interference • Detection limit down to 1 % biogenic content
References
1. ASTM D6866-22. Standard Test Methods for Determining the Biobased Content of Solid. Liquid. and Gaseous Samples Using Radiocarbon Analysis. DOI: 10.1520/D6866-22
2. SFS-EN 16640:2017. Bio-based products. Bio-based carbon content. Determination of the bio-based carbon content using the radiocarbon method.
3. DIN 51637:2014-02. Liquid petroleum products – Determination of the bio-based hydrocarbon content in diesel fuels and middle distillates using liquid scintillation method.
https://dx.doi.org/10.31030/2071672
4. ASTM D8473-22. Standard Test Method for Determining the Biobased content of Liquid Hydrocarbon Fuels Using Liquid Scintillation Counting with Spiked Carbon-14. DOI: 10.1520/ D8473-22
5. Matthew Hurt. Josephine Martinez. Ajit Pradhan. Michelle Young. and Michael E. Moir. Liquid Scintillation Counting Method for the Refi nery Laboratory-Based Measurements of Fuels to Support Refi nery Bio-Feed Co-Processing. Energy Fuels. 35. 2. 1503–1510 (2021). https://doi. org/10.1021/
acs.energyfuels.0c03445
6. Aronkytö et al. (2021) Method for determining a background count rate in liquid scintillation counting (U.S. Patent No. 11520058).
7. Aronkytö et al. (2022) Method for determining a background count rate in liquid scintillation counting (European Patent No. 4071520).
For more information please visit our website:
https://www.hidex.com/hidex-methods/measuring-procedures/hidex-biofuel-method
Author Contact Details Elmo Wiikinkoski • Hidex Oy • Address: Lemminkäisenkatu 62, FIN-20520 Turku, Finland • Tel: +358 10 843 5570 • Email:
info@hidex.com • Web:
www.hidex.com
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