Next Challenges for the Comprehensive Molecular Characterization of Complex Organic Mixtures in the Field of Sustainable Energy

Abstract

The conversion of lignocellulosic biomass by pyrolysis or hydrothermal liquefaction gives access to a wide variety of molecules that can be used as fuel or as building blocks in the chemical industry. For such purposes, it is necessary to obtain their detailed chemical composition to adapt the conversion process, including the upgrading steps. Petroleomics has emerged as an integral approach to cover a missing link in the investigation bio-oils and linked products. It relies on ultra-high-resolution mass spectrometry to attempt to unravel the contribution of many compounds in complex samples by a non-targeted approach. The most recent developments in petroleomics partially alter the discriminating nature of the non-targeted analyses. However, a peak referring to one chemical formula possibly hides a forest of isomeric compounds, which may present a large chemical diversity concerning the nature of the chemical functions. This identification of chemical functions is essential in the context of the upgrading of bio-oils. The latest developments dedicated to this analytical challenge will be reviewed and discussed, particularly by integrating ion source features and incorporating new steps in the analytical workflow. The representativeness of the data obtained by the petroleomic approach is still an important issue.

Keywords: bio-oil; derivatization; fractionation; high-resolution mass spectrometry; ion mobility; tandem mass spectrometry.

Figure 1

Typical petroleomic workflow: (A) acquisition of mass spectrum in high resolution mode (here LDI of coal-type sample); (B) distribution of mass measurement errors of assigned peaks after internal calibration of HR mass spectrum—the histogram is used to verify the normality of the error distribution; and (C) description of sample composition by various visualization tools.

Figure 2

New methodologies in petroleomics that contribute to the chemical characterization of bio-oil at the molecular level.

Figure 3

Venn diagram (A) and DBE vs. #O (B) of the CHO formulae obtained from ESI, APPI, and LDI FT-ICR MS analyses. The diagram was reprinted with permission from Ref. [17]. 2017, Elsevier.

Figure 4

Scheme of the experimental workflow from sample fractionation to gravimetric analysis and molecular characterization. The diagram was reprinted with permission from Ref. [95]. 2022, Elsevier.

Figure 5

DPF fractionation steps [98].

Figure 6

Main publications of IM-MS petroleomics [105,110,111,112,113,114,115,116,117,118,119].

Figure 7

2D TIMS-FT-ICR-MS survey spectra of the Athabasca asphalten. Reprinted with permission from Ref. [119]. 2021, Carlos Afonso.

Figure 8

Advantages of the different of IMS technology [108,121,122,123]. Instrument diagram reprinted with permission from Ref. [123]. 2011, Elsevier.

Figure 9

The outline for the isotope labelling.