Determination of Nitrogen Contents in Petroleum Products by Boat-Inlet and Chemiluminescence Detection According to ASTM D5762 Application Note · multi EA 5100

Introduction

Refinery samples are mixtures of various hydrocarbons (aliphatic, aromatic, polycyclic, etc.) resulting from the process of fractionated distillation of crude oil. Their boiling intervals, viscosities and combustion behavior vary in the same wide range. This makes it quite difficult to ensure equivalent analysis results for all matrix types. To avoid matrix effects like too low results or incomplete combustion, analysis in horizontal mode with boat inlet is the only suitable approach. Compared to vertical operation, the horizontal mode is disliked by many operators due to the remarkably increased analysis times and the necessity to create optimized combustion resp. boat programs for each matrix type and quantity. The quality of measurements is thus often a compromise between analysis time, desired sample throughput (analysis speed) and the dispersion of the measurement values.

Besides sulfur and chlorine, nitrogen is another important parameter to be monitored. For process and quality control widely varying TN contents have to be determined. While the focus during the refining process is mainly on TN traces, which can poison catalysts and result in undesired byproducts, product control and analysis of feed materials has to cover a wider concentration range. Contents up to the wt% range are common for matrices like crude oil, HC feeds, vacuum residues, but also for high-performance lube and engine oils.

The multi EA 5100 is specifically optimized for the fast and trouble-free analysis of widely varying TN contents in challenging matrices in horizontal mode. Combining catalyst-free high-temperature combustion and effective gas purification and drying with the highly sensitive HiPerSens CLD, it allows the direct detection of nitrogen at concentrations ranging up to 10,000 mg/L with one and the same device.