Revealing the Reactivity of Individual Chemical Entities in Complex Mixtures: the Chemistry Behind Bio-Oil Upgrading

Abstract

Bio-oils are precursors for biofuels but are highly corrosive necessitating further upgrading. Furthermore, bio-oil samples are highly complex and represent a broad range of chemistries. They are complex mixtures not simply because of the large number of poly-oxygenated compounds but because each composition can comprise many isomers with multiple functional groups. The use of hyphenated ultrahigh-resolution mass spectrometry affords the ability to separate isomeric species of complex mixtures. Here, we present for the first time, the use of this powerful analytical technique combined with chemical reactivity to gain greater insights into the reactivity of the individual isomeric species of bio-oils. A pyrolysis bio-oils and its esterified bio-oil were analyzed using gas chromatography coupled to Fourier transform ion cyclotron resonance mass spectrometry, and in-house software (KairosMS) was used for fast comparison of the hyphenated data sets. The data revealed a total of 10,368 isomers in the pyrolysis bio-oil and an increase to 18,827 isomers after esterification conditions. Furthermore, the comparison of the isomeric distribution before and after esterification provide new light on the reactivities within these complex mixtures; these reactivities would be expected to correspond with carboxylic acid, aldehyde, and ketone functional groups. Using this approach, it was possible to reveal the increased chemical complexity of bio-oils after upgrading and target detection of valuable compounds within the bio-oils. The combination of chemical reactions alongside with in-depth molecular characterization opens a new window for the understanding of the chemistry and reactivity of complex mixtures.

Petroleomics Approach to Investigate the Composition of Upgrading Products from Pyrolysis Bio-Oils as Determined by High-Field FT-ICR MS

“…Figure presents the molecular composition of the bio-oil feed and hydrotreated effluents determined via +APCI 12 T FT-ICR MS. Figure a shows the compound class distribution and highlights the favored detection of hydrocarbons with no heteroatoms (HC class). It is critical to consider that APCI FT-ICR MS provided no direct quantification of hydrocarbons, opposite to GC × GC; , however, it revealed compositional trends that suggest a maximum content of hydrocarbons for RCFP-1–2. These effluents showed a ∼2-fold increase in relative abundance as compared with bio-oil feed.…”

“…The development of efficient upgrading technologies for renewable fuels requires a comprehensive understanding of bio-oil molecular composition. , Two-dimensional gas chromatography, GC × GC, has dominated the field of chemical analysis for the volatile fraction of bio-oils and has been notably helpful to semiquantitatively classify compound families such as alkanes, cycloalkanes, and aromatics. − However, the nonvolatile fraction requires advanced instrumentation, such as high-field FT-ICR MS, as a large mass fraction of pyrolysis bio-oils are ultracomplex, nondistillable mixtures of polyfunctional O-containing molecules. , A typical bio-oil analysis by FT-ICR MS produces tens of thousands of mass spectral peaks. Ideally, each peak is assigned a unique molecular formula based on mass accuracy and isotopic patterns. , In general, molecular formulas are sorted into heteroatom classes; for instance, the O 3 class comprises all of the species with C, H, and three oxygen atoms.…”

GC-FTICR mass spectrometry with dopant assisted atmospheric pressure photoionization: application to the characterization of plastic pyrolysis oil

“…30 Heteroatom-containing classes were in common among both DI and GC but they observed a greater relative intensity with GC-APCI-FTICR MS for several heteroatom-containing compounds classes such as oxygenated compounds. The ability to separate isomers by chromatography enabled characterization of several reactive and hazardous compounds as shown by Barrow et al 25 in a study on soil sands, by Lozano et al 31 for the characterization of softwood bio-oil and its esterified product, or by Zuber et al for the characterization of pyrolysis oil from German brown coal. 12 All these works used extracted ion chromatograms of individual molecular compositions, determining the relationship with the retention time.…”

Chemoselective derivatisation and ultrahigh resolution mass spectrometry for the determination of hydroxyl functional groups within complex bio-oils

“…Bio-oils are complex mixtures not solely because of the large number of poly-oxygenated compositions, but because each molecule can exist in several isomeric forms, and contain different functional groups, 15 and therefore exhibit different properties that affect their behaviour under storage, processing, and upgrading. The structural characterisation of such a complex mixture remains a key goal for energy and environmental research.…”

“…Examples include the characterization of thiols in fossil fuels by Michael addition derivatisation, 23 Ag + complexation for the characterisation of olefin mixtures, 24 the derivatization of ketone/aldehyde functional groups in weathered petroleum, 25 the carbonyl group derivatization in an oak pyrolysis bio-oil by the use of 3-chloroaniline, 26 and the use of esterification reactions to gain insights in reactivity of bio-oil compositions. 15 Changes in the total abundance of heteroatomic class distributions after derivatisations are a clear indication of the presence of the targeted functional groups in complex mixtures.…”