Study of the Size Distribution of Sulfur, Vanadium, and Nickel Compounds in Four Crude Oils and Their Distillation Cuts by Gel Permeation Chromatography Inductively Coupled Plasma High-Resolution Mass Spectrometry

Abstract

The size distribution of sulfur, vanadium, and nickel was determined for four crude oils and their distillation cuts using gel permeation chromatography (GPC) coupled to inductively coupled plasma high-resolution mass spectrometry (ICP HR MS). The results show a trimodal distribution of vanadium and nickel compounds in the crude oils, the atmospheric residues, and the vacuum residues and, for sulfur compounds, either a mono- or bimodal distribution depending upon the distillation cut considered. A correlation exists between the sulfur fraction retention times and the temperature cuts of the distillation for a temperature below 560 °C and also between the viscosity of the crude oils and the proportion of trapped sulfur compounds in a higher boiling temperature fraction. The thermic treatment applied for the distillation increases the aggregation of low- and medium-molecular-weight compounds of vanadium and nickel into higher molecular weight aggregates between the crude oil on the one hand and the atmospheric residue and vacuum residue on the other hand, especially when the crude oil has a high total sulfur content.

Development of a chromatographic methodology for the separation and quantification of V, Ni and S compounds in petroleum products

“…ICP-HRMS is used as a specific detector for the determination of V, Ni and S, and the signal intensity for each compound as a function of the retention time is obtained. According toDesprez et al [27], the integration intervals corresponding to high-, medium-, and lowmolecularweight compounds (HMW, MMW, and LMW, respectively) were determined to be as follows: 1100-1400 seconds for HMW compounds, 1400-1600 seconds for MMW compounds and >1600 seconds for LMW compounds. In the rest of this work,we discuss the compounds in terms of their molecular weights; however, the compounds are sorted according to their hydrodynamic volumes and that what we call molecules'include noncovalent aggregates.…”

“…A post-column splitter was used to divide the flow (20:1). The low-flow outlet (50 μL/min)ledto the ICP-HRMS using a DS-5microflow, and thehigh-flow outlet (950 μL/min) was sent to waste.A similarsystem was previously described by Desprez et al (2014) [27]. Cummenet el all work in a separation scheme using HPLC with Xilene-THF gradient and GPC, finding that part of metal-complexes is retained on the column according to non-specific retention mechanism.…”

“…reported [27][28][29], and a summarized description is given below. A Thermo Scientific Element XR sector field ICP-HRMS instrument operated at a resolution of 4000 (medium resolution) was used to access spectrally interfered isotopes of laboratory-made, low-volume (8-mL), single-pass jacketed glass spray chamber without a drain, as described elsewhere [27].…”

Simplification of Heavy Matrices by Liquid–Liquid Extraction: Part I—How to Separate LMW, MMW, and HMW Compounds in Maltene Fractions of V, Ni, and S Compounds

“…2,3 A study performed using XAFS spectroscopy showed that the coordination shells of all compounds of V and Ni present in petroleum are very similar to those of vanadyl and nickel porphyrins. 4,5 In terms of their distribution in the products of petroleum, these compounds are almost all concentrated in atmospheric or vacuum residue based on their boiling points, 6 and they are present in asphaltenes and resins [7][8][9] when petroleum or residue is separated in their SARA fractions. Recently, three distinct families coexisting in the crude fraction of petroleum have been identified based on their molecular weight.…”

“…These have been identified as compounds with high, medium and low molecular weights (HMW, MMW and LMW). 6,9,10 This approach is relatively recent 6,9,10 and is due to the improvements made in their possible detection with ICP MS. Regarding these compound families, we believe that compounds with LMW correspond to simple metalloporphyrins (MPs), whereas compounds with MMW and HMW correspond to MPs trapped or linked in nanoaggregates 9,11 due to the high capacities of some crude oil compounds to trap different compounds.…”