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Bio-oils from biomass pyrolysis can be a resource for upgrading to chemicals or fuels. Here, for the first time, we compare the composition of bio-oils produced from two feedstocks (wheat straw, softwood) in pyrolysis units of different mode of operation (continuous—rotary kiln vs. batch) using Fourier transform ion cyclotron resonance mass spectrometry (FTICR MS) in different ionization modes (APPI (+), ESI (+/−)). Our results demonstrate that the pyrolysis unit design had only a minor influence on the composition of bio-oils produced from low-mineral containing wood biomass. Yet, the wheat straw-derived bio-oil produced in the continuous unit comprised lower molecular weight compounds with fewer oxygen-containing functional groups and lower O/C and H/C ratios, compared to bio-oils from batch pyrolysis. Longer residence time of vapours in the heated zone in the rotary kiln and a higher mineral content in wheat straw resulted in increased catalytically-mediated secondary reactions that favoured further bio-oil decomposition. This work shows for the first time that it is possible to produce distinct bio-oils without the need for external catalyst addition, by matching reactor type/design and feedstock.

Bio-oils obtained from the thermochemical conversion of the lignocellulosic biomass are potential sources of renewable materials (bio-fuels, chemicals, …). However, their high chemical complexity and the high amount of oxygenated compounds limit their ready-to-use capacity. Upgrading treatments, such as deoxygenation and/or cracking, have to be applied. In order to assess the most suited and the most efficient upgrading process, it is necessary to obtain an extensive composition description of the bio-oils at all processing stages. In this respect, the non-targeted approach, using Fourier transform high-resolution mass spectrometry combined with different ionization sources, has demonstrated its great abilities to characterize thousands of bio-oil components over a large range of mass and polarity. In this chapter, an exhaustive review of the studies performed in this field will be presented. To define the main challenges related to the bio-oil characterization, some relevant information will be briefly given in regards to the biomass composition and the used processes that ensure its conversion into bio-oils. Additionally, information achieved by “classical” analytical methods will be presented. This will allow demonstrating the contribution of high-resolution Fourier transform mass spectrometry (FTMS) analyses to characterization of bio-oils.

The conversion of lignocellulosic biomass by catalytic fast pyrolysis (CFP) is a promising route to producing green aromatics and sustainable biofuels. The zeolite catalysts present a strong ability to produce light aromatics but also heavy products. In this work, these heavy products are monitored by a well-established petroleomic approach. The selectivity toward the heavy bio-oil components of both a common HZSM-5 zeolite and a hierarchical zeolite was investigated. Part of the molecular species from lignin derivatives is still present in the upgraded bio-oils. Deoxygenation and aromatization are the main modifications of the heavy compounds caused by zeolites, especially for the sugar derivatives. These effects are stronger for the hierarchical zeolite for which numerous heavy hydrocarbons (not oxygenated) are generated due to enhanced mass transfers within the crystallites. Moreover, this catalyst demonstrates a better stability upon an increase in the biomass-to-catalyst ratio.

Ammonia is well suited to favor deprotonation process in electrospray ionization mass spectrometry (ESI-MS) to increase the formation of [M - H]-. Nevertheless, NH3 may react with carbonyl compounds (aldehyde, ketone) and bias the composition description of the investigated sample. This is of significant importance in the study of complex mixture such as oil or bio-oil. To assess the ability of primary amines to form imines with carbonyl compounds during the ESI-MS process, two aldehydes (vanillin and cinnamaldehyde) and two ketones (butyrophenone and trihydroxyacetophenone) have been infused in an ESI source with ammonia and two different amines (aniline and 3-chloronaniline). The (+) ESI-MS analyses have demonstrated the formation of imine whatever the considered carbonyl compound and the used primary amine, the structure of which was extensively studied by tandem mass spectrometry. Thus, it has been established that the addition of ammonia, in the solution infused in an ESI source, may alter the composition description of a complex mixture and leads to misinterpretations due to the formation of imines. Nevertheless, this experimental bias can be used to identify the carbonyl compounds in a pyrolysis bio-oil. As we demonstrated, infusion of the bio-oil with 3-chloroaniline in ESI source leads to specifically derivatized carbonyl compounds. Thanks to their chlorine isotopic pattern and the high mass measurement accuracy, (+) ESI Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) unambiguously highlighted them from the numerous CxHyOz bio-oil components. These results offer a new perspective into the detailed molecular structure of complex mixtures such as bio-oils. Graphical Abstract ᅟ.

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 CxHyOz 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.

International audience; The pyrolysis of the lignocellulosic biomass is a promising process to produce biofuels or green chemicals. Specific analytical methods have to be developed in order to better understand the composition of biomass and of its pyrolysis products and therefore to optimize the design of pyrolysis processes. For this purpose, different biomasses (Douglas and Miscanthus) and one biochar were analyzed by laser desorption/ionization Fourier transform ion cyclotron resonance mass spectrometry (LDI FT-ICR MS). This method allowed the biomass and biochar to be analyzed without any sample preparation and with a spatial resolution of about 100 μm. The influence of LDI conditions (laser wavelength and laser irradiance) and the nature of the biomass and biochar on the obtained mass spectrum were investigated. The nature and origin of the observed ions highly depended on LDI conditions. In the softest laser–biomass interaction conditions (low laser irradiance), the detected ions were related to the nature of the investigated biomass. Indeed, the main part of the detected species came from the different biomass subunits and was produced by photolysis of covalent bonds. When more severe laser irradiation conditions were used, the obtained mass spectra gathered the ions relative to (i) the chemical components of the investigated samples, (ii) the recombination products of these species in the gas phase after their ejection from the sample surface, and (iii) the compounds produced by laser pyrolysis of the sample. This was expected to be useful to mimic thermal pyrolysis.

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 me...