Anthony Dufour

High resolution solid state 2D NMR analysis of biomass and biochar.

Solid state NMR methods are required to analyze biomass as a function of its chemical or biological treatment for biofuels, chemicals, or biochar production. The native polymers network in lignocellulosic biomass and other solid materials, such as coal, coke, or biochar, can hardly be analyzed by liquid state NMR due to their poor swelling ability without chemical modification. A (1)H-(13)C two-dimensional heteronuclear correlation (HETCOR) experiment with frequency-switched Lee-Goldburg (FSLG) irradiation is performed on a high field spectrometer (750 MHz). This method leads to previously unattained resolution for biomass and biochar and offers a unique ability to reveal their chemical composition. The formation of aromatic moieties from carbohydrates and lignin thermal conversion is clearly distinguished. This method can be applied to all other carbonaceous materials.

Effect of potassium on the mechanisms of biomass pyrolysis studied using complementary analytical techniques

Complementary analytical methods have been used to study the effect of potassium on the pyrolysis mechanisms of cellulose and lignocellulosic biomasses. Thermogravimetry, calorimetry, high-temperature (1) H NMR spectroscopy (in situ and real-time analysis of the fluid phase formed during pyrolysis), and water extraction of quenched char followed by size-exclusion chromatography coupled with mass spectrometry have been combined. Potassium impregnated in cellulose suppresses the formation of anhydrosugars, reduces the formation of mobile protons, and gives rise to a mainly exothermic signal. The evolution of mobile protons formed from K-impregnated cellulose has a very similar pattern to the evolution of the mass loss rate. This methodology has been also applied to analyze miscanthus, demineralized miscanthus, miscanthus re-impregnated with potassium after demineralization, raw oak, and Douglas fir. Hydrogen mobility and transfer are of high importance in the mechanisms of biomass pyrolysis.

Catalytic fast pyrolysis of biomass: superior selectivity of hierarchical zeolites to aromatics

The catalytic fast pyrolysis of oak over two zeolites (microporous and hierarchical) was investigated in a microfluidized bed reactor (MFBR) at 500 °C and as a function of the biomass-to-catalyst ratio. A hierarchical zeolite was produced by desilication with a NaOH solution of a conventional HZSM-5 zeolite. The outlet of the MFBR was connected to a single photoionization mass spectrometer (SPI-MS) for the on-line analysis of volatiles. This on-line analysis method allows studying the dynamics of volatile formation (in real time) and the deactivation of 2 zeolites upon stepwise injections of wood particles. Strikingly, the selectivity of targeted mono-aromatic compounds (quantified by gas chromatography) is doubled after desilication of the zeolite. The coked zeolites were characterized by TEM-EDX, digestion in fluoric acid, MALDI-TOF MS, etc. Three different types of coke are evidenced: (1) coke trapped inside micropores, (2) external coke formed on the outer surface of the crystals and (3) coke precursors deposited in the mesopores. The latter two cokes are much less toxic than the microporous coke. The open mesopores produced after desilication can be seen as “highways” where big molecules (such as levoglucosan) can diffuse to more accessible pore mouths. Bronsted acid sites present on microporous mouths can be active for the conversion of bigger molecules to small fragments. These fragments diffuse and form aromatics in the micropores (shape selectivity). The mesopores also promote the evacuation of catalytic products, thus enhancing the selectivity of mono-aromatic hydrocarbons. Desilicated zeolites present higher selectivity to mono-aromatics and stability upon coke deposition than microporous zeolites.

Combination of electrospray ionization, atmospheric pressure photoionization and laser desorption ionization Fourier transform ion cyclotronic resonance mass spectrometry for the investigation of complex mixtures - Application to the petroleomic analysis of bio-oils

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.

Geological sequestration of biomass char to mitigate climate change.

L anthropogenic climate change requires developing new routes for energy supply with net negative emissions, such as bioenergy with carbon capture and storage (BECCS). To achieve this goal, many works have dealt with the land application of biochar or the sequestration of CO2 from biomass combustion. In my opinion, the concept of wood geostorage has not yet received enough attention. Here, I even propose to extend this concept to the geological sequestration of biochar (GSB), displayed on figure 1. I intend to open a debate on this concept and to argue on its potentials. (1). ABOUT BIOSPHERE MANAGEMENT AND THE POTENTIAL OF CARBON SEQUESTRATION BY BIOMASS

Semi-Targeted Analysis of Complex Matrices by ESI FT-ICR MS or How an Experimental Bias may be Used as an Analytical Tool

AbstractAmmonia 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 Abstractᅟ

La forêt : stock de carbone ou source d’énergie ?

La foret et les produits bois constituent un triple levier d’action contre le rechauffement climatique : la photosynthese sequestre le carbone de l’atmosphere en foret ; les produits bois recoltes prolongent le stockage du carbone durant leur duree de vie ; et ces memes produits bois peuvent se substituer aux carburants fossiles et aux materiaux energivores. A des echelles regionales et nationales, le choix de privilegier certains de ces leviers d’action requiert un arbitrage. Des outils de simulation sont donc necessaires pour evaluer l’ensemble du systeme, de la croissance forestiere jusqu’a la production energetique. Dans cet article, nous discutons d’avancees recentes en matiere de modelisation et de couplages de modeles visant a couvrir l’ensemble de la filiere foret-bois-energie. C’est a partir de tels couplages qu’il est possible d’evaluer le bilan environnemental de strategies visant a maximiser le stockage de carbone en foret, la sequestration dans les produits bois ou l’usage de biomasse forestiere a des fins energetiques. Des pistes d’amelioration, notamment en modelisation de la croissance forestiere, sont evoquees.

Kinetic Study of the Pyrolysis and Oxidation of Guaiacol

Guaiacol or 2-methoxy phenol is one of the main primary tars produced during lignin pyrolysis. Tar conversion in the gas phase influences the production of gaseous and condensable products, and is also responsible for PAH and soot formation during biomass and bio-oil gasification or combustion. Guaiacol pyrolysis and oxidation under stoichiometric conditions were studied in a jet stirred reactor between 623 and 923 K for a residence time of 2 s and under a pressure of 800 Torr (106.7 kPa). Speciation was obtained thanks to online gas chromatography using flame ionization detection and mass spectrometry and allowed the quantification of 22 species in pyrolysis and 42 species in oxidation. Decomposition of guaiacol starts at 650 K, and a conversion degree of 50% is obtained at about 785 K in pyrolysis and 765 K in oxidation. The main products of reaction are pyrocatechol o-HOC6H4OH, o-hydroxybenzaldehyde, methylcatechols, and light products, such as methane, carbon monoxide, ethylene, and hydrogen. A detailed kinetic model based on a combustion model for light aromatics and anisole has been extended to guaiacol. Thermochemical data of guaiacol and main products were calculated theoretically at the CBS-QB3 level of theory. The model predicts well the conversion of guaiacol and the formation of the main products. Guaiacol decomposes mainly through a unimolecular O-C bond breaking to hydroxy phenoxy and methyl radicals in both pyrolysis and oxidation, but H atom abstractions are also of importance in the low temperature range of the study. The unimolecular mechanism leads mainly to pyrocatechol and methylcatechols, whereas the chain radical mechanism is responsible for the formation of hydroxybenzaldehyde. As for anisole but in a much lower extent, an early formation of benzene and soot precursors is observed.

Diauxic growth of Clostridium acetobutylicum ATCC 824 when grown on mixtures of glucose and cellobiose

Clostridium acetobutylicum, a promising organism for biomass transformation, has the capacity to utilize a wide variety of carbon sources. During pre-treatments of (ligno) cellulose through thermic and/or enzymatic processes, complex mixtures of oligo saccharides with beta 1,4-glycosidic bonds can be produced. In this paper, the capability of C. acetobutylicum to ferment glucose and cellobiose, alone and in mixtures was studied. Kinetic studies indicated that a diauxic growth occurs when both glucose and cellobiose are present in the medium. In mixtures, d-glucose is the preferred substrate even if cells were pre grown with cellobiose as the substrate. After the complete consumption of glucose, the growth kinetics exhibits an adaptation time, of few hours, before to be able to use cellobiose. Because of this diauxic phenomenon, the nature of the carbon source deriving from a cellulose hydrolysis pre-treatment could strongly influence the kinetic performances of a fermentation process with C. acetobutylicum.