Characterization of Vanadyl and Nickel Porphyrins Enriched from Heavy Residues by Positive-Ion Electrospray Ionization FT-ICR Mass Spectrometry

Abstract

Petroporphyrins were enriched and purified from atmospheric residues of two typical heavy oils, Canadian oil sand bitumen (OSAR, Ni: 80 ppm, V: 190 ppm, S: 3.97 wt%) and Chinese Liaohe heavy oil (LHAR, Ni: 68.7 ppm, V: 1.81 ppm, S: 0.36 wt%) by silica gel chromatography. The separation and purification were confirmed by atomic absorption spectroscopy (AAS) combined with UV-vis spectroscopy, and the petroporphyrins were characterized by positive-ion electrospray ionization (ESI) Fourier transform-ion cyclotron resonance mass spectrometry (FT-ICR MS). Vanadyl and nickel porphyrins in OSAR are simultaneously identified by mass measurement and isotopic fine structure. Vanadyl porphyrins with structures of N 4 VO, N 4 VO 2 and N 4 VOS are all detected as protonated analyte ([M+H] + ). Both molecular ion (M +• ) and analyte ([M+H] + ) as well as their corresponding isotopes are observed for N 4 Ni porphyrins in OSAR and LHAR with an average mass resolving power of over 400 000 (m/∆m 50% ). This is rarely detected by FT-ICR MS using ESI technique previously. Formation of molecular ion can be attributed to the low oxidation potential of nickel porphyrins, effect of oil matrix on the solution conductivity and the relatively low flow rate of solution into the capillary. Three more highly unsaturated types of N 4 VO porphyrins were identified in addition to the six well-documented structures. Compared to N 4 VO porphyrins, N 4 VOS porphyrins present higher DBE ranging from 21 to 27 while N 4 VO 2 porphyrins show lower DBE ranging from 18 to 20 and narrower carbon number distribution, suggesting possible different origins of sulfur (pyrolysis of kerogen) and oxygen (diagenesis of chlorophyills). Ni/V and ratio of relative abundance of ETIO porphyrins to DPEP porphyrins (∑ETIO/∑DPEP) for nickel porphyrins indicate that Liaohe oil and Canadian oil sand bitumen are continental and marine sediment, respectively, and Liaohe oil has a higher maturity.Enrichment by the simple chromatographic method facilitates the mass spectral identification of nickel porphyrins even for heavy residue with low content of nickel and high content of sulfur.

Impact of iron porphyrin complexes when hydroprocessing algal HTL biocrude

“…Transient length was ~3 s. All observed ions were singly charged, as evident from unit m/z spacing between species which differ by 12 Cc vs. 13 C1 12 Cc-1.…”

“…1 Unlike other thermochemical processes (e.g., pyrolysis, gasification), the HTL approach eliminates the energy requirement for water removal/drying of wet feedstock. 2 Through the HTL process biomass slurry at ~5 -20% solids 3 is subjected to elevated temperature (280 -370 °C) and pressure (10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25) to produce liquid hydrocarbon oil as a principal product with biochar solids, aqueous-and gas-phase by-products. 4 Algal hydrothermal liquefaction oil has an energy density comparable to that of petroleum crude (42 MJ/kg) with reported heating values of 40-50 MJ/kg (Botryococcus brauni).…”

“…Metal-containing species (e.g., porphyrins) in petroleum cause bed plugging, increase coke formation, deactivate catalysts during upgrading and stabilize water-in-oil emulsions. [11][12][13] Porphyrins have high thermal stability which makes them difficult to eliminate 13 and metals within porphyrin complexes rapidly degrade catalysts. Nickel and vanadium are the two most abundant metals found in porphyrin structures in petroleum crude oil and concentration of 20-100 ppm and 50-250 ppm, are observed.…”

“…[25][26][27][28] FT-ICR MS coupled with atmospheric pressure photoionization (APPI) or electrospray ionization (ESI) has been used to characterize nickel and vanadyl porphyrins from heavy petroleum crude oil and natural seeps. 12,15,[29][30][31][32][33][34] Here, we apply electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI FT-ICR MS) to identify organometallic complexes, specifically iron-containing porphyrins, for the first time within algal HTL biocrudes. These compounds are responsible for bed plugging observed during hydrotreatment of the algae HTL biocrude.…”

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

“…Using Fourier transform ion cyclotron resonance (FTICR)-MS and a preseparation method to simplify the petroleum matrices, many groups [23][24][25] have found evidence of porphyrinic structures. However, previously, no spectroscopic evidence of non-porphyrin metal complexes (Ni and V=O) has been found [10].…”