We propose to assess the selectivity of hydrotreatment catalysts by two complementary analytical methods: (1) high-resolution mass spectrometry (MS), called “petroleomic” analysis, by Fourier transform ion cyclotron resonance (FT ICR, 9.4T) MS for species heavier than m/z of about 200 Da and (2) quantitative GC*GC (heart-cutting)/MS-flame ionization detector (FID) analysis of lighter species. The methodology is illustrated on methanol-soluble bio-oils produced by lignin pyrolysis and hydrotreated by iron-based catalysts. GC*GC analysis is calibrated by a combination of internal standard and prediction of response factors on the FID. Laser desorption ionization (LDI) and electro spray ionization (ESI) in negative-ion mode are combined for the petroleomic analysis. The selectivity of hydrotreatment (catalytic fixed bed, 1 atm, 400 °C) is assessed as a function of catalyst loads and iron support (silica and activated carbon). Hundreds of species are analyzed by GC*GC and petroleomic and mapped in Van Krevelen diagrams. The high selectivity of reduced iron for the hydrodeoxygenation of lignin pyrolysis vapors is demonstrated. The effect of the catalytic treatment on oxygen content and unsaturation is studied for a broad range of species: from C2 to C14 by GC analysis and from C8 to C37 by petroleomic. Many heavy lignin oligomers produced by the pyrolysis are trapped by the catalytic bed, highlighting the need of new catalytic systems to convert them into valuable fuels or chemicals.

The comprehensive description of complex mixtures such as bio-oils is required to understand and improve the different processes involved during biological, environmental or industrial operation. In this context, we have to consider how different ionization sources can improve a non-targeted approach. Thus, the Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) has been coupled to electrospray ionization (ESI), laser desorption ionization (LDI) and atmospheric pressure photoionization (APPI) to characterize an oak pyrolysis bio-oil. Close to 90% of the all 4500 compound formulae has been attributed to CHO with similar oxygen class compound distribution. Nevertheless, their relative abundance in respect with their double bound equivalent (DBE) value has evidenced significant differences depending on the ion source used. ESI has allowed compounds with low DBE but more oxygen atoms to be ionized. APPI has demonstrated the efficient ionization of less polar compounds (high DBE values and less oxygen atoms). The LDI behavior of bio-oils has been considered intermediate in terms of DBE and oxygen amounts but it has also been demonstrated that a significant part of the features are specifically detected by this ionization method. Thus, the complementarity of three different ionization sources has been successfully demonstrated for the exhaustive characterization by petroleomic approach of a complex mixture.

Pyrolysis or liquefaction processes can be applied to lignocellulosic biomass to produce a bio-oil which allows the access of green chemicals or sustainable energy. Among the different existing resources, this raw material has the advantage to come from nonfood feedstocks such as agricultural wastes (wood, grass, ...) or dedicated plantations. Whatever the considered bio-oil, the development of high performance analytical techniques is needed to achieve an exhaustive characterization. The use of Fourier transform ion cyclotron resonance mass spectrometry coupled to electrospray ionization (ESI-FT-ICR-MS) has the potential to chemically identify the components of bio-oil at the level of the molecular formula. In this work, we investigated the influence of the sample preparation (use and nature of dopant and ion detection mode) on the development of a robust methodology for lignocellulosic based bio-oil characterization. Commonly used ESI dopants have been studied to increase the ionization yield and the measurement repeatability. We highlighted the dramatic effect of the sample preparation on the global chemical description of the bio-oil, especially the disproportional contribution of the C x H y N 1−5 O z species. Moreover, we demonstrated the ability of well-controlled ESI ionization conditions to attain, on the one hand, specific chemical information on the origin (cellulose, hemicellulose, or lignin) of the bio-oil constituents and, on the other hand, the simultaneous description of both its oily and aqueous compounds without a fractionation step.

The understanding of lignin softening and pyrolysis is important for developing lignocellulosic biorefinery in order to produce carbon fibers, polymers additives, green aromatics, or biofuels. Protobind lignin (produced by soda pulping of a wheat straw) was characterized by thermogravimetry, calorimetry (for glass transition temperature and heat of pyrolysis reactions), in situ 1H NMR (for the analysis of the mobility of protons upon lignin thermal conversion), and solution-state 13C and 31P NMR (determination of functional groups in lignin). In situ rheology reveals the real-time viscoelastic behavior of lignin as a function of temperature. Upon heating, lignin undergoes softening, through glass transition overlapped with depolymerization, and is followed by the solidification of the softened material by cross-linking reactions. The lignin residues were quenched within the rheometer at the midpoint temperatures of softening and solidification regions and were further analyzed by elemental analysis, GPC-UV of acetylated THF soluble fractions, FTIR, solid 13C NMR, and laser desorption ionization (LDI) combined with very high-resolution mass spectrometry (HRMS). We present the first report on lignin biochars analysis by LDI-HRMS. NMR and FTIR analyses provide the evolution of functional moieties in lignin residues. 13C NMR, GPC-UV, and LDI FTICRMS analyses depict the depolymerization mechanism combined with cross-linking and demethoxylation reactions. An overall physical and chemical mechanism for the thermal conversion of alkali lignin is proposed based on these complementary analyses.

A proof-of-concept related to the redox-control of the binding/releasing process in a host-guest system is achieved by designing a neutral and robust Pt-based redox-active metallacage involving two extended-tetrathiafulvalene (exTTF) ligands. When neutral, the cage is able to bind a planar polyaromatic guest (coronene). Remarkably, the chemical or electrochemical oxidation of the host-guest complex leads to the reversible expulsion of the guest outside the cavity, which is assigned to a drastic change of the host-guest interaction mode, illustrating the key role of counteranions along the exchange process. The reversible process is supported by various experimental data ( H NMR spectroscopy, ESI-FTICR, and spectroelectrochemistry) as well as by in-depth theoretical calculations performed at the density functional theory (DFT) level.

The lack of standards to identify oligomeric molecules is a challenge for the analysis of complex organic mixtures. High‐resolution mass spectrometry—specifically, Fourier‐transform ion cyclotron resonance mass spectrometry (FT‐ICR MS)—offers new opportunities for analysis of oligomers with the assignment of formulae (CxHyOz) to detected peaks. However, matching a specific structure to a given formula remains a challenge due to the inability of FT‐ICR MS to distinguish between isomers. Additional separation techniques and other analyses (e.g., NMR spectroscopy) coupled with comparison of results to those from pure compounds is one route for assignment of MS peaks. Unfortunately, this strategy may be impractical for complete analysis of complex, heterogeneous samples. In this study we use computational stochastic generation of lignin oligomers to generate a molecular library for supporting the assignment of potential candidate structures to compounds detected during FT‐ICR MS analysis. This approach may also be feasible for other macromolecules beyond lignin.

Lignin is a potential renewable material for the production of bio-sourced aromatic chemicals. We present the first hydrotreatment of lignin pyrolysis vapors, before any condensation, using inexpensive and sustainable iron-silica (Fe/SiO2 ) and iron-activated carbon (Fe/AC) catalysts. Lignin pyrolysis was conducted in a tubular reactor and vapors were injected in a fixed bed of catalysts (673 K, 1 bar) with stacks to investigate the profile of coke deposit. More than 170 GC-analyzable compounds were identified by GCxGC (heart cutting)/flame ionization detector mass spectrometry. Lignin oligomers were analyzed by very high resolution mass spectrometry, called the "petroleomic" method. They are trapped by the catalytic fixed bed and, in particular, by the AC. The catalysts showed a good selectivity for the hydrodeoxygenation of real lignin vapors to benzene, toluene, xylenes, phenol, cresols, and alkyl phenols. The spent catalysts were characterized by temperature-programmed oxidation, transmission electron microscopy (TEM), and N2 sorption. Micropores in the Fe/AC catalyst are completely plugged by coke deposits, whereas the mesoporous structure of Fe/SiO2 is unaffected. TEM images reveal two different types of coke deposit: 1) catalytic coke deposited in the vicinity of iron particles and 2) thermal coke (carbonaceous particles ≈1 μm in diameter) formed from the gas-phase growth of lignin oligomers.

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