An Analytical Method for Screening Compositional Changes in Upgrading Catalytic refining Processes

Keywords:

Abstract:

There is a need to get the maximum of the oil barrel in terms of yield of light distillates, reducing the oil barrel bottoms. Fast and reliable analytical means are essential to monitor R&D efforts for conversion and upgrading processes. Conventionally, the physical characterization proceeds by obtaining the boiling range distribution by gas chromatography.The fact that the Retention time standard allowed to calibrate the system by boiling points of normal paraffins up to C199 and the fact that the Reference Oil produced a boiling point distribution within the ASTM consensus values as can be seen from Figure 2 and Table 2 prove that the sample has not been affected and that the experimental conditions of the standards methods were rigorously maintained.
Chemical characterization of high boiling hydrocarbon fractions is performed separately by low mass resolution mass spectrometry as per the ASTM standards1, D-2786 and D-3239. These methods require saturates and aromatics be separated by liquid chromatographic standard D-2549 or similar procedures. To avoid this time consuming separation step, there are available several high resolution mass spectrometric algorithms. However, the high costs associated with the instrumentation as well as the necessary expertise required for its use, exclude these methods from routine use.The similarity of both traces the MSD Total Ion Chromatogram and the FID Chromatogram also confirms the sample integrity.
The FID responds weakly to the carbon disulfide whereas in the mass spectrometer its signal is very intense. Other aspect that merits consideration is the background level and the column bleeding response being higher in the mass signal. These differences reflect the need to record inter sample blank runs. These blanks have to be subtracted from the corresponding previous sample signals.By simultaneously utilizing the FID and the MSD detectors while splitting the column effluent in a controlled way, it is possible to obtain identical gas chromatograms and total ion chromatograms from a single run. This means that besides the intensity vs. time graphs, the intensity vs. mass ions can also be obtained. As a result physical and chemical characterization can be performed in a simple and rapid manner.The simultaneous system was tested on high vacuum gasoil samples as well as aromatic and saturates fraction obtained according to D 2549 preparative liquid chromatography standard method.Experimental results on medium and heavy vacuum gas oils show clearly the effect of upgrading processes on the chemical composition and yields of diesel, jet fuels and high distillates. The methodology is fully compliant with ASTM SIMDIST D-2887, D-7213, D-6352, D7169 standard methods. It is expected to produce equivalent results to the conventional mass spectrometry ASTM standard methods2.

• Tagged
• XML
• BibTex