Heavy Fuel Oil, Feed Materials and Residues – Trustable Determination of High Nitrogen Contents in Viscous, Complex Matrices Application Note · multi EA 5100

Introduction

The worldwide growing demand for energy and the fact that the easy-to-find and cheap crude oil reserves are basically gone, force oil companies to process heavy crude oil and heavy fractions of the refining process (e.g. distillation residues, heavy fuel oil etc.) in an increasing extent.

Heavy fractions, as thick as molasses, are not only difficult to transport and handle, but also require advanced strategies for the compulsory quality control. For such matrices especially the nitrogen content is of interest due to its negative effects on the refining process (e.g. by poisoning of catalysts, unwanted sideproducts etc.).

The TN determination by means of high temperature combustion followed by chemoluminescence detection (CLD) is approved for analysis of light fractions like naphtha, gasoline, heating oil. The nitrogen compounds present are easydigestable pyridine and quinoline derivatives. The heavier the fraction, the higher is the content of more complex, poly-condensed nitrogen compounds (e.g. porphyrin). When being analyzed with the same method, these matrices deliver up to 25 wt% too low results for TN.

The typical boiling points of above 400 °C and relatively high nitrogen content exceeding 0.5 wt% make the investigation of these materials non-trivial. A dilution step before analysis to decrease the extremely high nitrogen content is often applied for small improvement, but it cannot eliminate this effect. An additional optimization of the digestion process is required to maximize the recovery up to ratios between 95–100 %. For this purpose we have developed the O2 + parameter mode.