TN Determination in Bio-based Fuels According to ASTM D4629 – Standard Test Method for Trace Nitrogen in Liquid Hydrocarbons by Syringe/Inlet Oxidative Combustion and Chemiluminescence Detection Application Note · compEAct N

Introduction

The production of alternative fuels becomes increasingly popular, as they provide a way to respond to both, the growing demand for energy and the goal to reduce carbon emissions. In addition to technologies based on the fermentation of starch and sugar, and the transesterification or hydrocracking of plant and animal oil (first generation biofuels), processes based on the conversion of cellulose-rich biomass and waste appear to be promising (second generation biofuels). With the use of biogenic materials for fuel production, their inherently high content of harmful hydrocarbons containing nitrogen, sulfur and chlorine has to be monitored. This is not only due to the adherence of given regulations and legal limits (Tier I–IV), but also to avoid negative effects on the production process, such as catalyst poisoning, and the environment. Even lowest levels of nitrogen compounds can seriously affect the performance and service life of catalysts, hence their ratio must be kept as low as possible. The desired TN content is far below 1 ppm, in general it should be around 100 ppb N. For this reason, a strict monitoring of the intermediate and final products is inevitable.

In ultra-trace analysis many factors influence the quality of analysis and thereby of course the final result. Besides the sensitivity of the detection system used, factors like the cleanliness of the apparatus used (system blank), the skills of the responsible operator (method development and adaptation to each sample matrix), the quality and suitability of the calibration used and, of course, the combustion quality (enabling sharp peak modulation) are highly important.

To eliminate or minimize all these possible error sources, a fast and catalyst-free high-temperature combustion in vertical operation mode and the use of the extremely sensitive HiPerSens detection technology is required. This eliminates matrixrelated method optimization which often leads to a confusing multitude of methods. Thanks to a quartz pyrolyzer, even matrices containing traces of heavier components can be digested completely without soot formation. This reduces the maintenance effort to a minimum.