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Application of biochar, a solid product produced from biomass pyrolysis under low oxygen conditions, has been suggested as a low emission technology capable of increasing soil C sequestration to mitigate climate change. Its combined application with compost may be a promising avenue to ameliorate soil quality while increasing C sequestration. We hypothesized that biochar addition to compost reduces the mineralization of the mixture compared to compost alone. The study aimed to compare the mineralization rate of six biochar-compost mixtures differentiated by biochar feedstocks. Biochars were produced at temperatures ranging from 450 to 650°C for 10 minutes. Our conceptual approach included incubation of fresh and artificially aged biochar-compost mixtures. Physical ageing of the mixtures was performed with successive cycles of humidification/drying and freezing/thawing. We evaluated elemental composition and biological stability of the fresh and aged mixtures after incubation with a soil inoculum for 1 year. We monitored components of biochar-compost mixtures decomposition when biochar were produced from C4 feedstock by determination of the 13C signature of emitted CO2.Combination of compost with biochar induced synergistic effects in terms of the mixtures stability. Isotopic analyses showed that carbon mineralization from compost was greatly reduced, while biochar mineralization was increased. Physical ageing induced a strong leaching of water-soluble compounds of both substrates. Carbon mineralization of aged material was however not reduced as much as expected when comparing with mineralization rates of single compounds of the mixture. Furthermore, isotopic signatures showed that compost, when amended with biochar, mineralized better after ageing. We thus suggest that the water-soluble fraction of biochar may induce an inhibitive effect on the mineralization of compost. The intensity of this effect seems to be dependent upon the feedstock of the biochar in the mixture.We conclude that biochar addition to compost may reduce the mineralization of the mixture depending on biochar feedstock and that this effect may be alleviated after ageing.

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 1H?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.

Accès restreint aux membres de l'Université de Lorraine jusqu'au 2016-12-31; Current research studies focus on biomass thermochemical conversion to produce other energetic vectors more appropriate to be conveyed, such as electricity, gas or liquid products. Pyrolysis is the first mechanism occurring in all thermochemical processes for solid fuels conversion (combustion, gasification, pyrolysis). It controls in a large extent products (gas, condensables and char) distribution and composition. The prediction of pyrolysis products and the understanding of the chemical mechanisms are thus pivotal for developing thermochemical reactors. Extensive work has been conducted for more than one century but the important heterogeneity of biomasses and pyrolysis conditions make it difficult to encompass a global chemical mechanism. The aim of this study is to develop complementary analyses of pyrolysis products. Pyrolysis is conducted in a fixed bed reactor under slow pyrolysis conditions (5 K/min), for a wide range of final temperature (200°C and 500°C) and for different biomasses (miscanthus, douglas and oak). Various analytical methods have been used in order to characterise the pyrolysis products: nuclear magnetic resonance (carbon 13C and proton 1H NMR), Calorimetry, Thermogravimetry, GC/MS (Gas Chromatography and Mass spectrometry), LC/MS (Liquid Chromatography and Mass Spectrometry) and soft ionization mass spectrometry (Single Photo Ionisation SPI). Original analytical methods such as 2D NMR HETCOR 1H-13C (for the analysis of chemical moieties in char) and high temperature 1H NMR (for in-situ analysis of mobile protons) have been used. The latter allowed a novel characterization of the interaction between biomass and minerals during pyrolysis; La pyrolyse est le premier mécanisme intervenant dans tous les procédés de conversion thermochimique des solides (combustion, gazéification, pyrolyse). C’est également le plus important, car il contrôle la répartition et la composition des trois types de produits : gaz, charbon, goudrons. La prédiction des produits de pyrolyse et est primordiale pour le développement de procédés de conversion thermochimique. De nombreuses études analytiques ont été réalisées mais la grande hétérogénéité des biomasses étudiées et des conditions de pyrolyse utilisées rend actuellement difficile une approche globale des mécanismes. L’objectif de cette étude a été de réaliser des analyses complémentaires de produits de pyrolyse formés pour une large gamme de températures (200°C à 500°C) en pyrolyse lente (5 K/min) pour différentes biomasses (miscanthus, chêne et douglas) à l’aide d’un lit fixe permettant un contrôle optimal des phénomènes de transfert de chaleur et de matière. De nombreuses méthodes physico-chimiques ont été utilisées pour caractériser les produits formés afin de réaliser un bilan global des mécanismes chimiques de dégradation : Résonance magnétique nucléaire (RMN) du proton 1H et du carbone 13C ; Calorimétrie (DSC) ; Thermogravimétrie ; GC/MS (Gas Chromatography and Mass spectrometry), LC/MS (Liquid Chromatography and Mass Spectrometry) et spectrométrie de masse à ionisation douce (Single Photo Ionisation SPI). Des techniques originales d’analyses dites ex-situ telles que l’analyse 2D RMN par la méthode HETCOR (Heteronuclear correlation) 1H-13C ainsi que des analyses in-situ en RMN 1H Haute Température ont été mises en place

Accès restreint aux membres de l'Université de Lorraine jusqu'au 2016-12-31; Current research studies focus on biomass thermochemical conversion to produce other energetic vectors more appropriate to be conveyed, such as electricity, gas or liquid products. Pyrolysis is the first mechanism occurring in all thermochemical processes for solid fuels conversion (combustion, gasification, pyrolysis). It controls in a large extent products (gas, condensables and char) distribution and composition. The prediction of pyrolysis products and the understanding of the chemical mechanisms are thus pivotal for developing thermochemical reactors. Extensive work has been conducted for more than one century but the important heterogeneity of biomasses and pyrolysis conditions make it difficult to encompass a global chemical mechanism. The aim of this study is to develop complementary analyses of pyrolysis products. Pyrolysis is conducted in a fixed bed reactor under slow pyrolysis conditions (5 K/min), for a wide range of final temperature (200°C and 500°C) and for different biomasses (miscanthus, douglas and oak). Various analytical methods have been used in order to characterise the pyrolysis products: nuclear magnetic resonance (carbon 13C and proton 1H NMR), Calorimetry, Thermogravimetry, GC/MS (Gas Chromatography and Mass spectrometry), LC/MS (Liquid Chromatography and Mass Spectrometry) and soft ionization mass spectrometry (Single Photo Ionisation SPI). Original analytical methods such as 2D NMR HETCOR 1H-13C (for the analysis of chemical moieties in char) and high temperature 1H NMR (for in-situ analysis of mobile protons) have been used. The latter allowed a novel characterization of the interaction between biomass and minerals during pyrolysis; La pyrolyse est le premier mécanisme intervenant dans tous les procédés de conversion thermochimique des solides (combustion, gazéification, pyrolyse). C’est également le plus important, car il contrôle la répartition et la composition des trois types de produits : gaz, charbon, goudrons. La prédiction des produits de pyrolyse et est primordiale pour le développement de procédés de conversion thermochimique. De nombreuses études analytiques ont été réalisées mais la grande hétérogénéité des biomasses étudiées et des conditions de pyrolyse utilisées rend actuellement difficile une approche globale des mécanismes. L’objectif de cette étude a été de réaliser des analyses complémentaires de produits de pyrolyse formés pour une large gamme de températures (200°C à 500°C) en pyrolyse lente (5 K/min) pour différentes biomasses (miscanthus, chêne et douglas) à l’aide d’un lit fixe permettant un contrôle optimal des phénomènes de transfert de chaleur et de matière. De nombreuses méthodes physico-chimiques ont été utilisées pour caractériser les produits formés afin de réaliser un bilan global des mécanismes chimiques de dégradation : Résonance magnétique nucléaire (RMN) du proton 1H et du carbone 13C ; Calorimétrie (DSC) ; Thermogravimétrie ; GC/MS (Gas Chromatography and Mass spectrometry), LC/MS (Liquid Chromatography and Mass Spectrometry) et spectrométrie de masse à ionisation douce (Single Photo Ionisation SPI). Des techniques originales d’analyses dites ex-situ telles que l’analyse 2D RMN par la méthode HETCOR (Heteronuclear correlation) 1H-13C ainsi que des analyses in-situ en RMN 1H Haute Température ont été mises en place

International audience; Pyrolysis of lignocellulosic biomass is one the main pathway for a renewable and sustainable production of energy such as biofuels. Many studies have focused on the characterization of the produced compounds to understand the pyrolysis mechanism. However, it is also of significant importance to exhaustively characterize the raw material and the produced biochar. Due to its sensitivity and its ability to investigate without preparation bulk complex systems, the laser desorption/ionization associated with FTICRMS is a very powerful tool. To the best of our knowledge, this technique is developed for the first time to reveal the chemistry of biomass and biochar, as well as to "map" the composition of particles. The experiments were conducted on different biomasses (douglas, oak, miscanthus) and on biochars Mass spectra were acquired on a 9.4 T-FTICR mass spectrometer coupled with different lasers. The investigated samples (wood and biochar) were introduced into the ionization chamber without further preparation step Mass spectra were post-processed and Van Krevelen diagrams, compound class distributions and DBE vs. C atom number diagrams were plotted. These diagrams were used to ensure an easy comparison of the different samples. Depending on the used experimental conditions (e.g. laser wavelength and laser fluence) different kinds of information were obtained whatever the investigated sample (raw wood and biochar). Strong differences in mass distributions were observed for the same sample under different laser ionization sources. In some cases, the resulting mass spectrum was highly connected to the sample components and in others, it corresponded to the superposition of different information: (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. The results were significantly complicated but still important and relevant information on the pyrolysis event were still possible to estimate. The comparison of the results obtained for a given raw wood and its biochar produced by "classical pyrolysis" has enabled identifying parts of the

International audience; Ranzi et al. proposed one of the most detailed biomass pyrolysis model [Ranzi et al., 2013]. The Ranzi lumped kinetic scheme is very interesting since it described the thermal decomposition of each biomass polymers (cellulose, hemicellulose and lignins) through 25 parallel and consecutive reactions that respect atomic balances. Thirty-nine molecules are defined: this allows to compute the gas and vapour composition but also the solid residue composition which is made of biomass polymers, char, but also different intermediates. In this work, we will present a comparison between the Ranzi model predictions and different experimental data that have been obtained with the following samples : Douglas fir, oak, miscanthus, extracts from miscanthus : cellulose, holocellulose and lignin organosolv. Slow pyrolysis data have been obtained through different setups: mass loss kinetics through Thermogravimetric analysis and heat release kinetics through Differential Scanning Calorimetry. A fixed bed setup allows to recover all the products that are characterized through elementary and molecular analysis. All these data could be compared with the Ranzi pyrolysis model predictions if the thermal conditions are well-understood. Fast pyrolysis experiments have also been achieved thanks to a micro-fluidized bed and an image furnace [Christodoulou et al., 2012]. In this case, there are internal temperature gradient in the solid particles during pyrolysis : the kinetic scheme of Ranzi model needs to be coupled to an accurate internal heat transfer model in order to compare simulated and experimental results. It will be shown that Ranzi model is a great progress in the field, even if there are still improvements to achieve so that it could represent all the features of biomass pyrolysis such as minerals catalytic effect. RANZI, Eliseo, CORBETTA, Michele, MANENTI, Flavio, et al. Chemical Engineering Science, 2013. CHRISTODOULOU, Mélina, MAUVIEL, Guillain, LÉDÉ, Jacques, et al. Journal of Analytical and Applied Pyrolysis, 2012.

International audience; This poster gives an overview of current research developed at CNRS Nancy (France) on the thermochemical conversion of lignocellulosic biomass. The main studied processes are pyrolysis and gasification to produce electricity, biofuels intermediates or value-added chemicals such as aromatics. A multiscale approach is developed ranging from molecular to process scales. The studies at molecular and mesoscopic levels give insight into the mechanisms of biomass pyrolysis and are used to design reactors. Conversely, the detailed mass and energy balances of processes point out process units with low energy efficiency and/or high environmental impact and stress the improvement of reactors and the need of more fundamental knowledge. The methodology will be highlighted by examples at: 1. the molecular scale: advanced NMR studies are used for understanding primary pyrolysis of biomass. Tar are analysed by photo-ionisation mass spectrometry and tar cracking kinetics are studied. 2. the mesoscopic and particle scales: the mechanism of biomass pyrolysis are studied by in-situ rheology and H NMR. Heat and mass transfers inside biomass particles are studied by specific devices with an imposed heat flux density (W/m2) [1]. 3. the reactor scale: Fluidised bed or cyclone are designed and home built in the lab. Advanced reactor models are developed and handled hydrodynamic, transfers and chemical kinetics. 4. the process scale: Bioenergy chains are modelled under Aspen Plus [2] to provide advanced life cycle inventory: from forest growth to end products. [1] JAAP 103, 255-260, 2013. [2] Energy & Fuels 27 (12), 7398-7412, 2013.

International audience; Biomass pyrolysis produces hundreds of compounds through an intermediate fluid phase. It is not yet understood how the network of biomass polymers (cellulose, hemicelluloses, lignin) gives rise to this intermediate "soft" network and how volatiles are ejected from this "metaplast" and then transported within the pores. To understand such mechanisms, it is needed to develop analytical methods for analyzing heavy species (eg. cellulose or hemicelluloses oligomers) which are ejected and condensed in bio-oils or extractables by water after a quench of biomass particles. Several HPLC methods were developed the past years and the most common ones are based on Ion Chromatography such as HPAEC-PAD (High Pressure Anion Exchange Chromatography coupled to a Pulsed Amperometric Detector). The lack of specificity in detection for this method was recently overcome by Yu et al. (Curtin Univ.). HPAED-PAD-MS coupling was developed to quantify liquid products from cellulose decomposition. However, due to a high salt content, an in-line desalter has to be used for mass spectrometry leading to a loss of information. Another way to overcome this problem is to use Size Exclusion Chromatography (SEC) especially because of its non-chemical selectivity, thus all type water-soluble content can be analyzed in addition to a high molecular mass limit (up to 4000 Da). Levoglucosan and DPs=2 to 5 polysaccharides were analyzed by both SEC-Evaporative Light Selective Detector (ELSD) combined by Electro Spray Ionisation (ESI)-Mass Spectrometry (MS), in order to compare accuracy in quantification between mass spectrometry ion signals and ELSD's signals. Ultimately, SEC has allowed a good separation of major cellulose oligomers and highly reproducible signals were observed with both detection techniques. Furthermore, this method is then applied to quantify carbohydrates pyrolysis products extracted by water from biomass particles after a quench at different temperatures. New major heavy intermediate species are revealed.

Mainly on biomass pyrolysis and gasification Physical-chemical insights are used to design reactors. Mass and energy balances of process stress theimprovement of reactors and the need of new fundamental knowledge