Oxidative Desulfurization Process Monitoring Using Comprehensive Two-Dimensional Gas Chromatography and Fourier Transform Ion Cyclotron Resonance Mass Spectrometry

Abstract

Clean fuel legislation throughout the world is driving the demand for ultralow-sulfur (<10 ppm) diesel (ULSD) fuel. Even though hydrodesulfurization remains the preferred technology to produce ULSD, the high associated costs lead to an increased interest in alternative processes, such as oxidative desulfurization (ODS). Monitoring the reacting species throughout the process is helpful for developing and/or optimizing ODS processes, although this has been difficult in real samples (complex mixtures). In this study, a hydrotreated diesel was subjected to a three-step ODS process (involving oxidation, extraction, and polishing) and thoroughly characterized using two-dimensional gas chromatography (2DGC) and Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). The obtained detailed speciation before and after each process step allows for monitoring the conversion of all sulfur species and assessing the process selectivity. The detailed analyses revealed that sulfur species from all families are converted to the corresponding sulfones. Therefore, benzothiophene, dibenzothiophene, and benzonaphthothiophene sulfones represent 90% of the total sulfur after the oxidation step. The comprehensive characterization revealed that, unlike the conventional hydrodesulfurization (HDS) process, the studied ODS process is selective for the oxidation and removal of HDS refractory sulfur species, such as dibenzothiophene and its alkyl derivatives, and less selective toward conventionally reactive sulfur species, such as thiophenes or benzothiophenes. Therefore, ODS may be used as a complementary method to HDS to achieve ultralow sulfur levels. Hydrocarbon conversion was also investigated, and this molecular class seems largely unaffected by the studied process. Nitrogen compounds are removed after the first process step through oxidation and/or extraction.

Towards a New Pseudo-quantitative Approach to Evaluate the Ionization Response of Nitrogen Compounds in Complex Matrices

“…A detailed quantitative characterization of both feeds (gas oils processed by hydrotreatment) and effluents (gas oils obtained after hydrotreatment) would be helpful to help understanding these mechanisms and thus improving the overall efficiency of hydrotreatment [20,21]. Some pseudoquantitative approaches for petroleum matrices have already been reported in the literature using mainly GC×GC analysis to evaluate the potential of FT-ICR MS as a pseudo-quantitative tool but mainly for sulfur compounds and without considering both basic and neutral nitrogen compounds [22][23][24]. Besides, these studies are based on a small number of gas oils which is not sufficient to identify a possible matrix effect from the gas oils and they did not consider simultaneously the impact of the other ionized families over the ionization response of a given family.…”

Towards a new pseudo-quantitative approach to evaluate the ionization response of nitrogen compounds in complex matrices

“…Some pseudo-quantitative approaches for petroleum matrices have already been reported in the literature using mainly GC × GC analysis to evaluate the potential of FT-ICR MS as a pseudo-quantitative tool but mainly for sulfur compounds and without considering both basic and neutral nitrogen compounds 22 – 24 . Besides, these studies are based on a small number of gas oils which is not sufficient to identify a possible matrix effect from the gas oils and they did not consider simultaneously the impact of the other ionized families over the ionization response of a given family.…”

Development of ‘Ready to Use Kits’ for the simultaneous qualification and quantification of drugs in different matrices using Mass Spectrometry, expanded with the application of multimodal imaging techniques

“…A mass spectrometer can be identified by three major components: an ion source (that produced gaseous ions from the substance being studied), a mass analyzer (which resolves the ion into their characteristics mass components according to their mass-to-charge ratio) and a detector (for the detection of ions and recording the relative abundance of each of the resolved ionic species) [5]. The introduction of "soft" ionization techniques, such as electrospray ionization (ESI) by Fenn et al [6] and matrix-assisted laser desorption ionization (MALDI) by Karas et al MSI allows for rapid detection, localization and identification of a tremendous amount of molecules from the most complex biological samples.…”

“…FDA, May 2001). All the parameters were validated considering the coefficient of variation (CV) of the ratio between the intensity of a certain analyte (A) and an internal standard (IS) over a variable number of repetitions (3-5) during several days (3)(4)(5). The methods were validated in terms of limit of detection, limit of quantification, precision, reproducibility, linearity, accuracy, recovery and selectivity.…”

“…Peak list generated from the literature containing expected peaks with relative m/z values in negative ion mode[5,17].…”