The National Institute of Standards and Technology (NIST) has developed a method to accelerate stability testing of biodiesel fuel made from soybeans and also identified additives that enhance stability at high temperatures. The results, described in a new paper,* could help overcome a key barrier to practical use of biofuels.
Both oxidation and heating can cause biodiesel to break down, adversely affecting performance. These two effects usually are analyzed separately, but NIST chemists developed a method to approximate both effects at the same time while also analyzing fluid composition. NIST’s “advanced distillation curve” method could accelerate and simplify testing of biodiesels, according to lead author Tom Bruno. NIST researchers used the new method to demonstrate the effectiveness of three additives in reducing oxidation of biodiesel at high temperatures, as would occur in aviation fuels.
Biodiesel—which can be prepared from vegetable oil, animal fats, used cooking oil, or microalgae—is a potential replacement or extender for petroleum-based diesel fuel. Biodiesel offers several advantages, including renewability, the potential for domestic production, biodegradability, and decreased emissions of carbon monoxide and particulate matter. Biodiesel also has several serious disadvantages, including increased nitrogen oxide emissions and chemical instability, especially at higher temperatures.
Antioxidants often are added to vegetable oils to retard oxidation during storage. The NIST work may be the first to enhance stability of biofuel at high temperatures, Bruno said. The study focused on three compounds, THQ, t-decalin and tetralin,** that help neutralize highly reactive “free radicals” formed at temperatures above 300 degrees C. Test results showed that all three compounds stabilized biodiesel. As expected from studies of aviation fuels, THQ and t-decalin perform similarly and outperform tetralin. For solutions containing 1 percent additive, THQ performed best overall.
A distillation curve charts the percentage of a mixture that evaporates as a sample is slowly heated. Because the different components of a complex mixture typically have different boiling points, a distillation curve gives a good measure of the relative amount of each component. NIST chemists enhanced the traditional technique by improving precision and control of temperature measurements and adding the capability to analyze the chemical composition of each boiling fraction.
To adapt the method for unstable fluids such as biodiesels, the authors made repeated distillation curves of samples and quantified the variation in parameters such as temperature for each distillate fraction across the different runs of the experiment. These data were averaged over the entire distillation curve to identify the range of variations that might occur. This range was extended to theoretically model the potential oxidative and thermal decomposition of the samples.
Two authors of the new paper participated in NIST’s Summer Undergraduate Research Fellowship (SURF) program.
* T.J. Bruno, A. Wolk and A. Naydich. Stabilization of biodiesel fuel at elevated temperature with hydrogen donors: Evaluation with the advanced distillation curve method. Energy & Fuels. Articles ASAP (Web), January 2, 2009. DOI: 10.1021/ef800740d.
* THQ: 1,2,3,4-tetrahydroquinoline; t-decalin: transdecahydronaphthalene; tetralin: 1,2,3,4-tetrahydronaphthalene.
Laura Ost | Newswise Science News
New tech for commercial Lithium-ion batteries finds they can be charged 5 times fast
20.02.2018 | University of Warwick
In best circles: First integrated circuit from self-assembled polymer
19.02.2018 | Max-Planck-Institut für Polymerforschung
For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.
In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...
Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale
Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...
For photographers and scientists, lenses are lifesavers. They reflect and refract light, making possible the imaging systems that drive discovery through the microscope and preserve history through cameras.
But today's glass-based lenses are bulky and resist miniaturization. Next-generation technologies, such as ultrathin cameras or tiny microscopes, require...
Scientists from the University of Zurich have succeeded for the first time in tracking individual stem cells and their neuronal progeny over months within the intact adult brain. This study sheds light on how new neurons are produced throughout life.
The generation of new nerve cells was once thought to taper off at the end of embryonic development. However, recent research has shown that the adult brain...
Theoretical physicists propose to use negative interference to control heat flow in quantum devices. Study published in Physical Review Letters
Quantum computer parts are sensitive and need to be cooled to very low temperatures. Their tiny size makes them particularly susceptible to a temperature...
15.02.2018 | Event News
13.02.2018 | Event News
12.02.2018 | Event News
20.02.2018 | Life Sciences
20.02.2018 | Medical Engineering
20.02.2018 | Physics and Astronomy