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A valourising process annexed to a recycling paper mill for converting three plastic-fibre rejects (PFRs) into oil, char and utility energy through pyrolysis provides renewable energy and prevents waste disposal. The economic and technical responses of the process are measured by varying the conversion temperature, feedstock characteristics and energy recovery approach, in order to optimise the processs. Previously measured responses of valourising PFRs were simulated in AspenPlus® according to variations in the fast-pyrolysis temperatures (350–550 °C); the contents of lignocellulosic fibres and plastics; and methods for adding value to excess process heat as steam and/or electricity. Economic models scaled at 540 kg/h were derived to determine the required minimum fuel selling price (MFSP) of the oil product. A base case for heat recovery assumes both steam and electricity. For a PFR stream composing mainly lignocellulose, the MFSP of oils ranged from 341 US$/GJ for pyrolysis at 350 °C to 65 US$/GJ for pyrolysis at 550 °C, while the process at 450 °C was most energy efficient. When only recovering steam from waste energy, the MFSPs were reduced by 6%. Pyrolysis of reject streams with increased plastics contents reduced the MFSP of the oil to 37 US$/GJ, due to the higher calorific value of the products. Increasing the feed rate of PFRs to 2400 kg/h could potentially reduce the MFSP to a market-competitive price of 15.3 US$/GJ, at a scale equivalent to a power-plant of 5MWe. PFRs containing higher proportions of plastics are preferred for valourisation through pyrolysis at 550 °C, while waste energy is best recovered as steam.

The production of phenols through catalytic pyrolysis of different types of lignin was investigated. Samples from eucalyptus (hardwood), pine (softwood), and sugarcane bagasse (herbaceous) were impregnated with the catalysts, Al2O3, ZnO, NaOH and KOH, in quantities equivalent to 1% of the lignin mass. Pyrolysis was conducted using thermogravimetric analyser (TGA), and the released phenols were captured in thermal desorption (TD) tubes for quantification by gas chromatography/mass spectrometry (GC/MS). From the TGA profiles, some modifications in the primary mechanisms were observed, especially with the hydroxide catalysts. In comparison to non-catalysed lignin pyrolysis, KOH produced the most statistically significant effect on the total phenols yields from sugarcane bagasse (S-S) lignin, with increases up to +26%, while NaOH increased the yield from Eucalyptus (E-K) lignin by +40%. Syringol was the main S-type phenol product, with the highest yield increase by NaOH from E-K lignin (+90%) and a final yield of 1.86 wt.%. NaOH also produced the highest yield increases of G-type phenols from E-K lignin, especially 4-vinylguaiacol (+39% and yield of 2.80 wt.%). The increased production of primary compounds (S-type and G-type) by these hydroxides was probably correlated with the enhanced depolymerisation in the first decomposition stages, as observed by TGA. Oxide catalysts had limited effects on the production of S-type and G-type compounds but were more selective towards the production of P-type phenols, especially ZnO with S-S lignin (+36%) due to the enhancement of demethoxylation reaction.

Pyrolysis is finding increasing application as a tool for the effective management of industrial waste, as it can process a wide variety of heterogeneous feedstock into energy dense products. Inductively heated fast pyrolysis with heating rate of 250 °C min−1 was applied for conversion of three industrial waste streams from a fibre recycling mill, contaminated with plastic wastes, into energy products. Experiments were carried out at three different temperatures (350, 450 and 550 °C) and the yields and energy contents of the char, oil, wax and gas products were determined. For all three waste streams, conversion at 350 °C, mostly concentrated the energy in the char, resulting in calorific values between 20.9 MJ kg−1 and 35.1 MJ kg−1 which are comparable to common bituminous coal used for power generation. Pyrolysis at 450 or 550 °C promoted the formation of condensable volatiles (wax/liquid) with total wax yields of up to 54 wt.% being obtained at 550 °C, with the calorific value up to 41.7 MJ kg−1 comparable to heavy fuel oil. The estimated net energy yield for the three waste streams ranged from 10 to 25 MJ (kg dry feedstock)−1 with the largest energy yield being obtained for the stream containing the largest fraction of hydrocarbon plastics.

The structural nature of lignin renders it suitable as a renewable source of phenolic compounds. The production of phenols from pyrolysis of sugarcane lignins with impregnated catalysts was investigated by screening of twelve catalysts (Al2O3, CaO, Fe2O3, TiO2, ZnO, MgO, CuO, MoO3, NiO, Ni/Al2O3-SiO2, NaOH, and KOH) at 1 wt.% content. Sugarcane bagasse lignins were isolated after soda-pulping (SD), soda-anthraquinone-pulping (SAQ) and steam explosion pre-treatment followed by enzymatic hydrolysis (SEH). Pyrolysis was conducted using a thermogravimetric analyser (TGA), and captured volatiles were quantified by thermal desorption (TD) gas chromatography–mass spectroscopy (GC–MS). The TGA results showed that the degradation profiles and char yields were influenced by the presence of catalysts, through modifications in conversion mechanisms. The highest increases in the total yield of phenols were obtained with KOH for SD lignin (+25.7%), CaO for SAQ lignin (+59.7%), and Fe2O3 for SEH lignin (+43.0%). Due to the enhancement of depolymerisation at low temperature (

The effect of combined quinone reductase (QR) and lignin peroxidase (LiP) on the depolymerization of technical lignins isolated from soda-anthraquinone (SAQ), steam explosion (S-E), and two sulfite processes (NaE and NaPE) was investigated. While LiP is best known for its ability to degrade lignins, it may also cause lignin re-polymerization due to the random coupling of phenoxy radicals and quinoid intermediates. This study evidenced that the addition of the bioreactor produced QR can to some extent limit the lignin re-polymerization by LiP. The synergistic application of QR and LiP lowered the molecular weights (Mw) of SAQ, NaE, S-E, and NaPE lignins by 31%, 34%, 41%, and 52%, respectively. The thermogravimetric analysis also showed that the thermal stability of the four lignins was reduced, whereas gas chromatography-mass spectrometry analysis showed that the degradation products included monomeric phenols. Therefore, the combined QR and LiP system is a promising approach for lignin valorization.

A range of energy fuels (ethanol, char, oil/wax and gas) was produced from fibre waste contaminated with plastic through the application of a fermentation-pyrolysis route. The fibre component was first converted to ethanol by simultaneous saccharification and fermentation (SSF), achieving an ethanol concentration of 39.8 g/L. The residue, enriched in lignin and plastics, was subjected to fast pyrolysis at temperatures between 350 and 550 °C. A wax product with a higher heating value (HHV) higher than 28 MJ/kg was obtained for temperatures higher than 450 °C, while values lower than 15 MJ/kg were observed for the oils produced from the untreated waste stream. Pyrolysis at 550 °C produced a wax with an HHV as high as 32.1 MJ/kg, where 51.8% of the energy content of the fermentation residue was transferred. The attractive energy contents of the pyrolysis products were enabled by oxygen removal from the feedstock during fermentation to ethanol.

This study investigated the influence of torrefaction (300 °C) on the combustion performances of blends of biomass-plastic wastes (Mango branches (MBr), newspaper (Np), LDPE) using thermogravimetric analysis. The torrefied waste blends were co-combusted with coal at a blending ratio of 25 and 50 wt. % to identify possible interactions between the fuels’ components. Synergistic behaviours were noted during combustion of the torrefied MBr-Np blend and the comprehensive combustion index, Dc was 29 % higher than the predicted value. Interestingly, synergistic interactions were perceived during co-combustion of the different wastes with coal. The measured burnout temperatures (TBO) of all torrefied waste-coal blends were lowered by 6–15 %, compared to their predicted values, especially for MBr-Np-coal blends. Synergistic interactions during torrefaction of MBr-Np not only improved the combustion reactivity of the resulting char but also enhanced coal combustion in the blend compared to combustion of torrefied biomass-LDPE-coal blends. It was concluded that synergies during co-combustion of waste char with coal were governed by the waste type, its composition and the interactions that prevailed during torrefaction of the wastes.

This study investigated the pyrolysis of polystyrene (PS) packaging waste for transportation fuel application of the oil product, with a specific focus on the effect of contamination and the scale-up of the process. The oil yield and calorific value were optimised at bench scale in a semi-batch reactor with temperature and heating rate as input factors. The process was then scaled up to a semi-continuous rotary kiln reactor and the oil product was characterised in terms of fuel properties. Oil yields of 89.8-93.2 wt.% with higher heating values (HHV) of 42.1 ± 0.5 MJ/kg were achieved at bench scale with virgin PS. Heavy meat juice contamination (15.9 wt.% dry contamination) decreased the oil yield by 6.4 wt.%, but did not affect the HHV significantly. Due to more losses at pilot scale, a lower oil yield of 82.5 ± 1.4 wt.% was achieved and the gross energy recovered in the oil was 88.0 ± 2.6%. Fuel characterisation indicated that the oil contained substantially less inorganic and sulphur than the waste feedstock. However, for commercial use blending with conventional fuel would be necessary to mitigate the aromatic content of the oil.

To establish the potential of thermally pretreated biomass as fuel for coal replacement in applications such as gasification, the fuel properties (higher heating value, elemental and proximate analyses) and the composition of char devolatilization products were analyzed and compared to those of sub-bituminous coal. Samples of pine, bamboo, corn cob and corn stover were pretreated at 250, 300, 350 and 400 °C with a hold time of 30 min. The devolatilization experiments were done in a Thermogravimetric analyzer, while captured volatiles were analyzed by thermal desorption/gas chromatography–mass spectrometry. The results showed that an increase in pretreatment temperature consistently decreased the oxygen and volatile matter contents of the char, while its fixed carbon content and the higher heating values increased, with a more drastic evolution from 300 °C onwards. Analysis of the char devolatilization products confirmed a major modification of the polysaccharides structure, as only traces of depolymerisation products were observed following pretreatment at 350 °C. Devolatilization of chars pretreated at 350 and 400 °C resulted in the evolution of the tar precursors, especially the phenolics, at similar and lower amounts, respectively, in comparison to coal devolatilization. Overall, a pretreatment temperature of at least 350 °C would be recommended for sub-bituminous coal substitution in gasification, while 400 °C could be considered for biomass species with high lignin content.

Lignocellulosic samples of Lantana camara (LC) and Mimosa pigra (MP) were pre-treated by torrefaction (300 °C) or pyrolysis (>500 °C) in order to study their potential use as co-fuels with coal. Combustion of the resultant chars, three coals and some blends was investigated by thermogravimetric analysis (10 °C min−1). The effects of biomass composition, pre-treatment temperature of char and blending ratio, on combustibility parameters of ignition, burnout and combustion indices were determined. The addition of reactive char in the fuel mixture consistently resulted in the reduction of ignition temperature, while lowered burnout temperatures of the blends indicated interactions between char and coal during co-combustion. Blends up to 15% showed similar combustion characteristics as those of the parent coals, with co-combustion occurring within the coal combustion zone. Most of the lowest combustion indices were obtained at 30% blends, mainly due to combustion occurring over a wider temperature range, while for blends ≥60%, co-combustion took place in the char combustion zone, with better co-combustion efficiencies, by up to 244% for 90% blend when compared with parent coal. Comparatively, pyrolysed char blends recorded higher combustion indices than torrefied sample blends. The results also showed that lignocellulosic composition of the precursor influenced the combustion mechanisms.

Pyrolysis of invasive non-indigenous plants, Lantana camara (LC) and Mimosa pigra (MP) was conducted at milligram-scale for optimisation of temperature, heating rate and hold time on char yield and higher heating value (HHV). The impact of scaling-up to gram-scale was also studied, with chromatography used to correlate gas composition with HHV evolution. Statistically significant effects of temperature on char yield and HHV were obtained, while heating rate and hold time effects were insignificant. Milligram-scale maximised HHVs were 30.03MJkg-1 (525°C) and 31.01MJkg-1 (580°C) for LC and MP, respectively. Higher char yields and HHVs for MP were attributed to increased lignin content. Scaling-up promoted secondary char formation thereby increasing HHVs, 30.82MJkg-1 for LC and 31.61MJkg-1 for MP. Incondensable gas analysis showed that temperature increase beyond preferred values caused dehydrogenation that decreased HHV. Similarly, CO evolution profile explained differences in optimal HHV temperatures.

Lignin is the most abundant natural source of renewable aromatic units and therefore, detail characterisation to unveil its chemical properties is a critical step for its utilisation. Nine black liquor samples from different plant origins namely sugarcane bagasse, Eucalyptus grandis , and Pinus gregii extracted from the Kraft, soda, soda-anthraquinone and sulphite pulping processes were considered. After lignin purification, when applicable, the samples were characterised by several common methods (wet chemical methods, Fourier Transformed Infra-Red spectroscopy, Gel Permeation Chromatography). Lignin monomer composition (H:G:S) was determined by thioacidolysis as well as a new pyrolysis method based on the use of an analytical set-up which couples Thermo Gravimetric Analysis (TGA) for lignin devolatilisation, the capture of released volatile compounds in thermal desorption (TD) tubes, and the quantification of the captured phenols by TD-GC–MS (gas chromatography–mass spectroscopy). The TGA-TD-GC–MS, with the use of internal calibration, allowed the quantification of 5.5–12.9 wt.% of monomeric products based on dry weight of purified lignin. Pyrolysis of sugarcane lignin resulted in significant yield of furfural, which was explained by the conversion of residual sugar. Pyrolysis of pine lignin gave the lowest yield of syringyl-type phenols, which was consistent with characterisation results (low methoxy content and absence of FT-IR band characteristic of syringyl unit). Pyrolysis method had the advantage to break different types of chemical bonds, which is likely to give a product distribution more representative of the lignin. With TGA-TD-GC–MS the monomer proportion for purified lignin from the same plant species were found to be very comparable (deviation lower than 10% for each unit). Compared to thioacidolysis (known to be selective towards bond cleavage and suspected to overestimate S content), TGA-TD-GC–MS gave lower S/G ratio. The TGA-TD-GC–MS method has demonstrated to be a good alternative technique to study the H:G:S proportions of lignins with low ash content (

Pyrolysis is a promising technology for the production of marketable energy products from waste mixtures, as it decomposes heterogeneous material into homogenous fuel products. This research assessed the ability of slow pyrolysis to convert three waste streams, composed of fibre residues contaminated with different plastic mixtures, into char and tarry phase products at three different temperatures (300, 425 and 550 °C). The products were characterised in terms of mass yield, higher heating value (HHV) and gross energy conversion (EC). Significant amounts of hydrocarbon plastics in the feed materials increased the calorific values of the char (up to 32.9 MJ/kg) and tarry phase (up to 42.8 MJ/kg) products, comparable to high volatile bituminous A coal and diesel respectively. For all three waste streams converted at 300 °C, the majority of the energy in the feedstock was recovered in the char product (>80%), while deoxygenation of fibre component resulted in char with increased calorific value (up to 31.6 MJ/kg) being produced. Pyrolysis at 425 °C for two of the waste streams containing significant amounts of plastic produced both a valuable char and tarry phase, which resulted in an EC greater than 74%. Full conversion of plastic at 550 °C increased the tarry phase yield but dramatically decreased the char HHV. The influence of temperature on product yield and HHV was discussed based on the pyrolysis mechanisms and in relation to the plastic composition of the waste streams.

This study compared the pyrolysis of waste polypropylene (PP) into fuel products under atmospheric and vacuum pressure conditions at different temperatures and heating rates. Four different temperatures (450, 488, 525 and 600 °C) at slow (15 °C/min) and fast (about 180 °C/min) heating rates were examined on a bench scale reactor. Pyrolysis vapours were recovered as heavy and light fractions by fractional condensation and characterised using GC/MS. Among all temperatures, 488 and 525 °C generated promising yields of condensable products under both atmospheric and vacuum conditions, with total yields in the range of 81–93 wt%. Heating rate effects on product composition distribution were more pronounced under vacuum pyrolysis. Gasoline range compounds predominated in light condensable products recovered under both atmospheric and vacuum pyrolysis. Vacuum suction limited the condensation of gasoline range compounds in the heavy fraction, resulting in Diesel/Gasoline ratio higher than 30. Higher Heating Values (HHVs) of all condensable products recovered under both atmospheric and vacuum conditions ranged between 41 and 46 MJ/kg, with higher values being obtained under milder conditions. Increased production of aromatics explained the lower HHVs obtained at higher temperatures.

This paper investigated the interactive effects between biomass and plastic, derived from municipal solid wastes, during co-torrefaction of their mixtures. Mango branches (MBr), waste newspaper (Np), low-density polyethylene (LDPE) and their blends were torrefied at 300 °C at a constant heating rate of 10 °C/min for 30 min using a bench-scale reactor. Statistically significant interactions were found between MBr and Np during torrefaction of MBr-Np and MBr-Np-LDPE blends. The synergistic behaviour in torrefied MBr-Np accounted for its improved energy density, reduced volatile matter content, increased carbon content and higher fuel ratio than expected. During co-torrefaction with plastic, melted LDPE limited mass transfer, which resulted in higher char yield and energy content. Analysis of combustion indices revealed that waste blending ratio of torrefied biomass-LDPE blends should be limited to 5 wt%, due to the high volatile matter content of LDPE. This study elucidates that among the different torrefied blends, synergistic interactions during co-torrefaction of waste biomass (MBr-Np) generated a char with improved fuel characteristics that allowed co-firing of biomass at higher blending ratios (20 wt%).

Pyrolysis of forest residues using CaO and MgO catalysts was carried out in an induction heating reactor, to produce an upgraded bio-oil with increased higher heating value (HHV). Optimisation with central composite design (CCD) included temperature (444−656 °C) and catalyst concentration (1.7–58.3 wt.%). A fractional condensation system with the first condenser heated to 40 °C was used to collect an organic-rich oil. The optimum HHV of the oil was 26.9 MJ/kg (560.0 °C and 33.8 wt.% catalyst) at 19.4 wt.% yield with MgO and 26.4 MJ/kg (550.0 °C and 30.0 wt.% catalyst) at 18.9 wt.% yield with CaO (based on a desirability function used to obtain significant oil yield). The combination of water-gas shift reaction (WGSR) catalysed by CaO and the fractional condensation system resulted in water content of the oil at the optimum of only 7.8 wt.%. Absorption of CO2 by CaO, together with significant H2 production (400 % increase compared to non-catalytic case) allowed the production of a gas calorific value of 13.7 MJ/kg compared to 5.2 MJ/kg without catalyst.

In this work, we prepared iron- or nickel-impregnated cellulose to examine the influence of the metal on the yield and composition of fast pyrolysis products. In order to identify the mechanisms promoted during the catalytic conversion, pyrolysis was investigated using an experimental set-up coupling TG (thermogravimetric) analysis and Micro-GC (Gas Chromatography). The results showed that with relatively low catalyst loading (mass fraction of 1.5% Fe or 1.7% Ni) impregnated metal can catalyze some rearrangement reactions such as dehydration and decarboxylation starting from 180 °C, promoting the char formation and thus inhibiting cellulose depolymerization. As a consequence metal impregnation led to a decrease of tar and CO yields balanced by an increase of char, H2O and CO2 yields. Depending on the applied metal, other primary reactions can be specifically catalyzed. In particular, in the presence of nickel TG analysis revealed an important mass loss at temperatures as low as 210 °C and an important increase of H2 production in the temperature range 400–500 °C. These findings open promising perspectives to optimize the production of fuels and chemicals from biomass. (Resume d'auteur)

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The conversion of biomass by thermochemical means is very promising for the substitution of fossil materials in many energy applications. Given the complexity of biomass the main challenge in its use is to obtain products with high yield and purity. For a better understanding of biomass thermochemical conversion, many authors have studied in TG analyzer or at bed scale the individual pyrolysis of its main constituents (i.e. cellulose, hemicelluloses and lignin). Based on these studies, this original work synthesizes the main steps of conversion and the composition of the products obtained from each constituent. Pyrolysis conversion can be described as the superposition of three main pathways (char formation, depolymerization and fragmentation) and secondary reactions. Lignin, which is composed of many benzene rings, gives the highest char yield and its depolymerization leads to various phenols. The depolymerization of the polysaccharides is a source of anhydro-saccharides and furan compounds. The fragmentation of the different constituents and the secondary reactions produce CO, CO2 and small chain compounds. For temperature higher than 500 °C, the residues obtained from the different constituents present a similar structure, which evolves towards a more condensed polyaromatic form by releasing CH4, CO and H2. As the aromatic rings and their substituent composition have a critical influence on the reactivity of pyrolysis products, a particular attention has been given to their formation. Some mechanisms are proposed to explain the formation of the main products. From the results of this study it is possible to predict the reactivity and energy content of the pyrolysis products and evaluate their potential use as biofuels in renewable applications.

Decades of aerosol measurements on Barbados have yielded a detailed picture of African mineral dust transport to the Caribbean Basin that shows a strong seasonal cycle with a maximum in boreal summer and a minimum in winter. Satellite aerosol products suggest that in spring, there is a comparable transport to northeastern South America. Here we characterize the complete annual cycle of dust transport to the western Atlantic by linking the Barbados record to multiyear records of airborne particulate matter less than 10 µm diameter (PM10) measured in air quality programs at Cayenne (French Guiana) and Guadeloupe. Comparisons of PM10 at these sites with concurrent dust measurements at Barbados demonstrate that high PM10 levels are almost entirely due to dust. Cayenne PM10 peaks in spring in a cycle which is consistent with satellite aerosol optical depth and suggests that the Sahel is the dominant source. The persistent transport of dust during much of the year could impact a wide range of environmental processes over a broad region that extends from the southern United States to the Amazon Basin. Finally, the average 24 h PM10 concentrations at Cayenne and Guadeloupe frequently exceed the World Health Organization air quality guideline. Thus soil dust PM10 could be a significant, but generally unrecognized, health factor at western Atlantic sites and also in other relatively remote regions affected by long-range dust from Africa. Because dust emissions and transport are highly sensitive to climate variability, climate change in coming decades could greatly affect a wide range of biogeochemical processes and human health in this region.

The performance of vacuum, slow and fast pyrolysis processes to transfer energy from the paper waste sludge (PWS) to liquid and solid products was compared. Paper waste sludges with low and high ash content (8.5 and 46.7 wt.%) were converted under optimised conditions for temperature and pellet size to maximise both product yields and energy content. Comparison of the gross energy conversions, as a combination of the bio-oil/tarry phase and char (ECsum), revealed that the fast pyrolysis performance was between 18.5% and 20.1% higher for the low ash PWS, and 18.4% and 36.5% higher for high ash PWS, when compared to the slow and vacuum pyrolysis processes respectively. For both PWSs, this finding was mainly attributed to higher production of condensable organic compounds and lower water yields during FP. The low ash PWS chars, fast pyrolysis bio-oils and vacuum pyrolysis tarry phase products had high calorific values (∼18-23 MJ kg-1) making them promising for energy applications. Considering the low calorific values of the chars from alternative pyrolysis processes (∼4-7 MJ kg-1), the high ash PWS should rather be converted to fast pyrolysis bio-oil to maximise the recovery of usable energy products.

The paper and pulp industry is one of the major industries that generate large amount of solid waste with high moisture content. Numerous opportunities exist for valorisation of waste paper sludge, although this review focuses on primary sludge with high cellulose content. The most mature options for paper sludge valorisation are fermentation, anaerobic digestion and pyrolysis. In this review, biochemical and thermal processes are considered individually and also as integrated biorefinery. The objective of integrated biorefinery is to reduce or avoid paper sludge disposal by landfilling, water reclamation and value addition. Assessment of selected processes for biorefinery varies from a detailed analysis of a single process to high level optimisation and integration of the processes, which allow the initial assessment and comparison of technologies. This data can be used to provide key stakeholders with a roadmap of technologies that can generate economic benefits, and reduce carbon wastage and pollution load.

In this chapter the application of pyrolysis technologies for the fractionation of lignocellulosic plant biomass into a range of fuels, chemicals, and materials is considered. The outcome of such fractionation can be manipulated through either the process conditions in the pyrolysis reactor itself and/or the process conditions in the subsequent condensation of liquid products for the separation of gaseous products. Temperature is shown to have the greatest impact on the formation of chemical species in the pyrolysis reactor, affecting both the yields and composition/characteristics of the gaseous, liquid, and solid products. The separation of solid, liquid, and gaseous products downstream from the pyrolysis reactor offers an opportunity for the selective isolation of specific chemical fractions in the liquid condensation train, an approach that may be valuable in a biorefinery context. Apart from the discussion of pyrolysis and separation mechanisms, perspectives are also offered on product applications and the industrial implementation of pyrolysis processes as biorefineries.

When impregnated in biomass, metal precursors display catalytic activity that results in a significant decrease in tar production and increases hydrogen formation during pyrolysis. The aim of this work was to assess the effect of nickel and iron salts on the pyrolysis mechanisms of the main constituents of biomass. Samples of metal-impregnated cellulose, hemicelluloses (beech wood xylan) and lignin were pyrolyzed. Beech wood samples with different metal contents (0.10, 0.26 and 0.65 mmol/gwood) were also tested to compare the effects of iron and nickel in the biomass. As a result of metal impregnation, significant changes in the yields of pyrolysis products, in the concentration of tar compounds (determined by GC-MS) and in the composition of the gaseous fraction were obtained. The results showed that in cellulose, xylan and lignin, impregnated iron catalyzed rearrangement reactions leading to an increase in char yield and a decrease in tar formation. Impregnated nickel also catalyzed charring reactions in microcrystalline cellulose and in lignin, but promoted the depolymerization of amorphous xylan resulting in a 27-fold increase in furfural yields. Nickel was more efficient than iron in the rearrangement of the aromatic rings in the matrix, which contributed to the large increase in hydrogen production observed with nickel-impregnated samples (+472% for nickel-impregnated lignin). Based on these results, it was possible to explain the changes in pyrolysis yields obtained from beech wood after metal impregnation. The comparison of the catalytic effect of the two metals on biomass constituents explained the higher char yield and tar decrease obtained with iron-impregnated wood on one hand, and the higher aromatic tar reduction and hydrogen production increase obtained with nickel-impregnated wood on the other hand. (Resume d'auteur)

A thermogravimetric analysis technique coupled to an evolved gas analysis, namely the thermal desorption/gas chromatography–mass spectrometry method (TGA–TD/GC-MS) was developed, to identify and quantify condensable volatile compounds produced during the pyrolysis of lignocellulose. Four lignocellulose samples of different origins (i.e., pine, bamboo, corn cob and corn stover) were pyrolysed using a TGA system. Condensable volatiles released during pyrolysis were captured onto thermal desorption tubes and subsequently identified and quantified using a TD/GC–MS method. Chemical composition of condensable volatiles was statistically correlated with the original lignocellulose composition, using Principal Component Analysis (PCA). A total of 15–19 wt% (dry weight) of biomass pyrolysis products were quantified by the method, with an average Relative Standard Deviation on the high concentration condensable volatiles yield of 6.4%, a significant improvement to what has been reported in literature. The first two principal components accounted for 89.4% of the variance in the data and showed clear correlations between evolved condensable volatile compounds and compositional differences among the four biomass samples. The origin of most lignin-derived compounds could be determined, due to the limitation of secondary reactions under slow pyrolysis. The yield of levoglucosan and 5-hydroxymethylfurfural were consistent with the initial content of C 6 sugars in the feedstock, but also negatively correlated with the ash content. The quantification of acetic acid, the highest yielding condensable volatile product, can be used as an indicator of the number of acetyl groups in biomass.

In previous work, we showed that two-step biomass pyrolysis, consisting of a first low temperature step ( T = 360 °C, so a low actual heating rate) until the mass loss of the solid reached approximately 50%, followed rapidly by a high temperature step ( T > 600 °C, so a high actual heating rate) led to optimize charcoal yields with values of up to 40%. In this paper, we describe thermogravimetric analysis studies on eucalyptus wood and its three constituents, i.e. cellulose, xylan and lignin, in order to explain the phenomena behind these results. Two-step pyrolysis experiments were conducted in a TGA oven up to 900 °C with a first slow pyrolysis step at a low heating rate of 2 °C min −1 , followed by a fast pyrolysis step with a heating rate of 100 °C min −1 . Char yields from eucalyptus wood were increased from 18.8%, for the simple 2 °C min −1 pyrolysis, up to 22.8% when the heating rate change was operated at a temperature of 360 °C. Char yield from cellulose was also increased, though only very slightly, when the heating rate was changed in the 330–360 °C temperature range. Conversely, char yield obtained from xylan and lignin in two-step pyrolysis was always lower than that obtained by simple 2 °C min −1 pyrolysis. It appeared from this work that two-step pyrolysis of the eucalyptus sample could not be regarded and described as the result of the sum of the pyrolysis of its constituents. There was a matrix effect with interactions that promoted char formation during two-step pyrolysis.

In order to establish a chemical fingerprint of vanilla diversity, thirty samples of V. planifolia J. W. Moore and V. tahitensis G. Jackson cured beans from seven producing countries were examined for their aroma and fatty acid contents. Both fatty acid and aroma compositions were found to vary between vanilla species and origins. Vanillin was found in higher amounts in V. planifolia (1.7-3.6% of dry matter) than in V. tahitensis (1.0-2.0%), and anisyl compounds were found in lower amounts in V. planifolia (0.05%) than in V. tahitensis (1.4%-2.1%). Ten common and long chain monounsaturated fatty acids (LCFA) were identified and were found to be characteristic of the vanilla origin. LCFA derived from secondary metabolites have discriminating compositions as they reach 5.9% and 15.8% of total fatty acids, respectively in V. tahitensis and V. planifolia. This study highlights the role of the curing method as vanilla cured beans of two different species cultivated in the same country were found to have quite similar fatty acid compositions.

In order to establish a chemical fingerprint of vanilla diversity, thirty samples of V. planifolia J. W. Moore and V. tahitensis G. Jackson cured beans from seven producing countries were examined for their aroma and fatty acid contents. Both fatty acid and aroma compositions were found to vary between vanilla species and origins. Vanillin was found in higher amounts in V. planifolia (1.7-3.6% of dry matter) than in V. tahitensis (1.0-2.0%), and anisyl compounds were found in lower amounts in V. planifolia (0.05%) than in V. tahitensis (1.4%-2.1%). Ten common and long chain monounsaturated fatty acids (LCFA) were identified and were found to be characteristic of the vanilla origin. LCFA derived from secondary metabolites have discriminating compositions as they reach 5.9% and 15.8% of total fatty acids, respectively in V. tahitensis and V. planifolia. This study highlights the role of the curing method as vanilla cured beans of two different species cultivated in the same country were found to have quite similar fatty acid compositions.