-Characterization of Nitrogen and Sulfur Compounds in Hydrocracking Feedstocks by Fourier Transform Ion Cyclotron Mass Spectrometry -Advanced characterization of two heavy hydrocracking unit feedstocks, Heavy Vacuum Gas Oil (HVGO) and De-Metallized Oil (DMO), both derived from Arabian Light crude oil, was performed using High Resolution Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR MS) to gain in-depth information on their aromaticity characteristics and heteroatom content, i.e., sulfur-and nitrogen-compounds. In
We investigated the conversion of light paraffinic naphtha (C5-C6) into BTX (benzene, toluene, and xylenes) aromatics using 1.0 wt % Pt-M/ZSM-5 (modifier M = 1 wt% Zn, 2 wt % of Fe, La, Ga) prepared using wet-impregnation method. The effects of Pt and modifier on light naphtha conversion, yield and aromatic selectivity (benzene, toluene, xylene, C9 + aromatics) were studied in fixed-bed flow reactor in atmospheric pressure, at 550°C, and WHSV 1.0 h À 1. Catalytic efficiency of modified Pt or Pt-M ZSM-5 catalysts has been equated to conventional ZSM-5 [Si/Al 2 = 30] catalyst. While the yield of total aromatics was slightly increased over Pt/ZSM-5 comparison to parent ZSM-5 from 32 wt % to 37 wt %, the value for in situ formed mesoporous Pt-Ga/ZSM-5 was significantly improved reaching 60 wt %. The higher selectivity to aromatics is attributed to the induced mesoporous volumes and dehydrogenation activity of Ga species. These species associated with Pt were effective in the conversion of light naphtha to olefins, which later converted into aromatics by secondary reactions: cracking, isomerization and dimerization. The Pt-Ga/ZSM-5 showed good stability toward the selective production of aromatics at a low toluene/benzene ratio ∼ 0.5 due to Pt component.
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.
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