Characterization of Acidic Species in Athabasca Bitumen and Bitumen Heavy Vacuum Gas Oil by Negative-Ion ESI FT−ICR MS with and without Acid−Ion Exchange Resin Prefractionation

Abstract

Because acids in petroleum materials are known to corrode processing equipment, highly acidic oils are sold at a discount [on the basis of their total acid number (TAN)]. Here, we identify the acidic species in raw Canadian bitumen (Athabasca oil sands) and its distilled heavy vacuum gas oil (HVGO) as well as acid-only and acid-free fractions isolated by use of an ion-exchange resin (acid-IER) and negative-ion electrospray ionization Fourier transform ion cyclotron resonance (ESI FT-ICR MS) mass spectrometry. The ultrahigh mass resolving power (m/∆m 50% > 400 000) and high mass accuracy (better than 500 ppb) of FT-ICR MS, along with Kendrick mass sorting, enable the assignment of a unique elemental composition to each peak in the mass spectrum. Acidic species are characterized by class (N n O o S s heteroatom content), type [number of rings plus double bonds to carbon or double-bond equivalent (DBE)], and carbon number distribution. We conclude that the analytical capability of FT-ICR MS and the selectivity of the ESI process eliminate the need for acid fractionation to characterize naphthenic acids in bitumen. However, because the acid-free fraction (not retained on the acid-IER) contains S x O y heteroatomic classes not observed in the parent bitumen, acid-IER fractionation does help to identify such low-abundance species. Further, we observe that a subset of the acids identified in the parent bitumen distill into the HVGO fraction. Variations in the carbon number and aromaticity of the classes are discussed in detail.

Analysis of extractable basic nitrogen compounds in Buliangou subbituminous coal by positive-ion ESI FT-ICR MS

“…7 (9-12) and CN (18)(19)(20)(21)(22)(23) than those in E 1 and E 3 . In addition, few species with DBE < 4 were detected, suggesting that few saturated and unsaturated aliphatic amines exist in N 1 O 1 and N 1 O 2 classes.…”

“…It has been successfully applied in molecular characterization of complex mixtures, such as petroleum products [21,22], shale oil [20], bio-oils [23][24][25] and coal derivates [26][27][28]. Meanwhile, electrospray ionization (ESI), a soft ionization technique, can selectively ionize polar molecules.…”

Evaluating the hydrophilic–lipophilic nature of asphaltenic oils and naphthenic amphiphiles using microemulsion models

“…The naphthenic acid purchased from Sigma-Aldrich is described as a technical grade extract from crude oil (no defined origin) with an acid number of 230 g/equivalent, which we use here as its molecular weight [29,30]. Recent studies have shown that naphthenates obtained from Alberta's oil sands have similar composition to those found in Sigma-Aldrich naphthenates, and are enriched in C 12 -C 16 fatty acid equivalents with 3-6 double bond equivalents [31].…”

Catalytic aquathermolysis of Shengli heavy crude oil with an amphiphilic cobalt catalyst

“…Combined with soft ionization methods, e.g., electrospray ionization (ESI), FT-ICR MS was applied to investigate catalytic aquathermolysis of heavy oil (Wu et al 2005;Smith et al 2008;Colati et al 2013;Wang et al 2013). 10 mg oil sample was firstly dissolved in 1 mL toluene, and then diluted with toluene/ methanol (1:3, v/v) to yield a 0.2-mg/mL solution.…”