In the current energy context, pallet boards represent a wood of opportunity strongly used on an individual scale as a means of heating at a low cost. However, French stoves are certified to burn only hardwood species. The main objective of this work is to study the combustion behavior of pallet boards in a commercial stove designed to burn hardwood. The novelty of this work lies in the study of the influence of the wood surface exposed to fire and the identification of the conditions that promote the production of ultrafine particles. The results of the combustion tests show that the surface exposed to the fire influences the combustion. Of the six wood dispositions tested, two stand out with gaseous and particulate emissions at similar levels of a conventional hornbeam log and a densified log. Low temperature conditions and high levels of unburned gaseous products were identified as promoters of ultrafine particles. Overall conclusion of the study is that it is possible to use pallets in a non-designed stove, provided that the user carefully manages the combustion. This opens the way to the clean and rational use of a new type of fuel in a low carbon circular economy.

A panel of twenty commercial briquettes representative of the French market was set up with the different actors of the French densified log industry. The selected briquettes were characterized via the determination of their water and ash content, their ultimate and elemental composition and their heating value. Pollutant emission factors during the combustion of the briquettes were evaluated in real conditions in a domestic stove with natural draught. Gaseous pollutants like CO, CO2, NOx, SO2 and THC (Total HydroCarbons) were monitored. Particulate emissions in mass (TSP) and number (PM2.5) were also measured. Briquettes characterizations showed that the majority of the data determined in laboratory are in agreement with the one announced by the producers. Moreover several briquettes are in agreement with limitation established by the EN ISO 17225 standard. Combustion tests showed that the use of densified fuel instead of traditional log does not lead to a significant degradation of the environmental performances of the stove. Some briquettes present emission factors close to the one measured with traditional wood log. Several recommendations concerning briquettes characteristics were drawn from this study.

To simulate the oxidation of Biodiesel soot in a catalyzed Diesel Particulate Filter, oxidation experiments of undoped or Na-doped model soot were performed in the presence of Pt-Pd/Al2O3 under Temperature Programmed Oxidation and different carbon-catalyst configurations. Loose or tight contact was simulated by mixing soot and catalyst either with a spatula or in a mortar. Samples were characterized by Flame Atomic Adsorption Spectroscopy, Inductively Coupled Plasma-Optical Emission Spectroscopy, N-2-physisorption, X-ray Photoelectron Spectroscopy, Raman Spectroscopy and Transmission Electron Microscopy coupled with Energy Dispersive X-Ray. The results showed that reducing the carbon granulometry led to an enhancement of the reactivity under NO2, due to the external combustion mechanism of carbon crystallite. In the absence of catalysts, no impact of the granulometry was observed under a flue gas containing NO and O-2. A better catalyst efficiency was obtained when the carbon-catalyst contact was increased. In tight contact, a mechanism where NO2 can react adsorbed on a metallic site with a carbon site was proposed. In the presence of water, a simple addition of the catalytic activity of both water and Pt-Pd/Al2O3 catalyst impact on carbon oxidation was observed. The use of Biodiesel, simulated by Na-doped model soot, led to a significant increase in the catalyst efficiency in loose contact. Thus, a second mechanism was proposed, assuming that the doped sites play the role of NO2-reservoir and carrier between catalyst and carbon sites.

Ordered mesoporous SBA-15 and COK-12 supports with similar mesopore diameter were loaded with 15 wt% of CuO and evaluated as adsorbents in a desulfurization process involving SOx adsorption and regeneration. Both SBA-15 and COK-12 have a hexagonal arrangement of parallel tubular mesopores. The impact of relatively small differences of the structural and textural properties of the two supports on SOx adsorption and regenerability is investigated. After impregnation with copper nitrate solution and calcination at 500 degrees C, the samples do not show any characteristic XRD pattern of copper-based phases, confirming the highly dispersed state of CuO, which is also checked by Transmission Electron Microscopy (TEM). The COK-CuO15 sample has slightly higher porosity than the SBA-CuO15 sample. The pore volume of both supports is slightly reduced after impregnation-calcination and shaping (Pelletized, Crushed and Sieved - PCS) steps. As for its SOx adsorptive properties, after fifteen adsorption-regeneration cycles at 400 degrees C, the COK-CuO15_PCS sample exhibits dynamic and total adsorption capacities higher than those of the SBA-CuO15_PCS adsorbent. In addition, both adsorbents preserve their adsorption capacities over the 15 cycles. The COK-12 support for the CuO active phase provides very promising results in comparison with the literature data for SBA-CuO15 adsorbent.

This work aims to evaluate the impact of bentonite content on the structural, textural and mechanical properties of SBA-15 beads prepared by shearing using an Eirich mixer. X-Ray Diffraction analysis (XRD) of conventional and sheared SBA-15 powders and bentonite–containing beads confirms the attainment of hexagonal structure. According to the nitrogen adsorption–desorption isotherms, the bentonite content has a significant impact on mesoporous volume. SBA-15 beads containing 9.1 wt% of bentonite (B-SBA-Be9), 16.7 wt% of bentonite (B-SBA-Be17) and 33.3 wt% of bentonite (B-SBA-Be33) showed an increase in mesoporous volume of 15, 25 and 20%, respectively. Indeed, the presence of the basic bentonite-water solution during the preparation stage of the beads generates a chemical attack of the SBA-15 walls that leads to the increase in the mesopores size. Beads containing 16.7 wt% of bentonite present more promising result in relation to their good balance between textural properties and mechanical strength. Thus, this sample could be used for a future application as a catalyst support for desulfurization process. Therefore, these results confirm that porosity and mechanical resistance are strongly dependent on the bentonite content and beads preparation process, in comparison to literature data.

The impact of engine operating cycle, Biodiesel blends and fuel impurities on soot production and soot properties are evaluated in the present work. To this end, soot were produced on engine test bench and then collected inside a Diesel Particulate Filter (DPF). Two engine cycles (a Natural Loading and an Accelerated Loading) were tested. A standard Euro VI fuel blended with 7% of Biodiesel (B7) and a pure Biofuel (B100 RME EN 14214) were used. This latter was additivated with potassium and phosphorus at a low (B100+) or at a high (B100++) concentration. Soot characterization through elemental analyses, nitrogen adsorption, Raman spectroscopy, TGA and TPO experiments show that the engine operating cycle impact the soot reactivity through modifications of their texture and structure. Test bench experiments also show that increasing Biodiesel blend from B7 to B100+ divides by five the soot production. Moreover, soot obtained with B100+ are more reactive because of higher oxygen and ash content. When the inorganic content of the fuel is increased, few effects on the soot production are observed but the soot reactivity is significantly increased. In fact, analyses highlight that impurities present in the fuel are retrieved inside the soot composition and then catalyze their oxidation. K has a beneficial effect on both passive and active regenerations. On the contrary, P inhibits the active regeneration but has a significant catalytic impact on the CNO2H2O reaction. Finally, a numerical simulation allows to extract the kinetic constants of real B7- and B100+-soot, whose values confirm the differences of the soot reactivity.

Soot model (Carbon Black (CB)) were impregnated by Na, K or P in aqueous solution, to simulate the poisoning process of soot by biodiesel impurities. Oxidation of non-doped and doped CB samples was performed under Temperature Programmed Oxidation (TPO) and under different oxidizing atmospheres containing NO2 to simulate passive regeneration conditions. Active regeneration conditions were tested through thermogravimetric analyses (TGA). Alkali metals exhibit a beneficial effect on the oxidation process through the whole temperature range, regardless the reactive gas flow. Phosphorus has a beneficial effect on C-NO2 reaction, particularly in presence of water, but inhibits the C-O-2 reaction. Characterizations of the samples through elemental analysis, X Ray Photoelectron Spectroscopy (XPS), nitrogen adsorption and Raman spectroscopy prove that alkali metals increase the specific surface area of CB samples and lead to a decrease in their internal structure order. Impregnation of CB samples by phosphorus leads to a decrease in specific surface area and to a greater organization of the carbon structure. The kinetic constants which are derived through numerical simulations prove that the higher reactivity of doped CB samples is linked to a decrease in activation energy of both C-NO2 and CO2-NO2 reactions and an increase in the number of active sites.

Since 2014 (Euro VI), heavy goods vehicles must be equipped with a complex exhaust gas post-treatment system including a diesel oxidation catalyst (DOC), a catalyst for the selective reduction of NO x (SCR), and a diesel particulate filter (DPF), with a required durability of 7 years or 700,000 km. Consequently, when biodiesel is used, especially pure biodiesel (B100), catalysts will be subjected over 700,000 km to kilogrammes of inorganic elements (Na, K, and P), even if they are limited to a few ppm in biodiesel fuel. The durability of the catalytic exhaust system is therefore questionable. This issue is of major concern to vehicle manufacturers. This study aims to make a detailed investigation of the impact of biodiesel use on the durability of the existing Euro VI catalytic systems, with a special focus on deactivation through poisoning for DOC and SCR catalysts, and on the physics and chemistry of particles and their reactivity.

Simultaneous NOx reduction and soot combustion over a commercial vanadia-based selective catalytic reduction (SCR) catalyst were investigated. Carbon black was used as model soot. The impact of the contact intensity between carbon and catalyst was studied. The experiments appeared as promising results for the utilization of vanadia-based SCR catalysts in SCR on filter system as, in the SCR operating temperature range (250-400 degrees C), no significant impact of the presence of carbon black on NOx reduction was observed. However, a decrease in the specific carbon oxidation rate was highlighted. This latter increases with the contact between carbon and catalyst and is attributed to a lack of NO2, consumed by the fast SCR reaction. At temperatures greater than 400 degrees C, the contact between carbon particles and the SCR catalyst partially inhibits the NOx reduction, whereas it exhibits a catalytic effect on the carbon oxidation rate. The tighter the contact between the two materials, the more significant is this behavior. A redox mechanism, which competes with the redox cycle of the SCR mechanism, was proposed. The impregnation of a V-based SCR catalyst with 2 wt % of calcium was also performed. A drastic loss of DeNO(x) activity was observed, whereas the effect of the contact between carbon and catalyst was reduced. (C) 2017 Academie des sciences. Published by Elsevier Masson SAS.

The aim of this work is to quantify to what extent the presence of calcium, zinc and/or phosphorus, in realistic concentrations, affects the efficiency of a commercial full body type SCR V catalyst used for off-road vehicles. Samples containing Ca, Zn and P, and combinations thereof, were prepared by incipient wetness impregnation of the catalyst. The loading of these elements was set at 0.24 or 1 wt%. Experiments carried out on samples with a loading of 0.24 wt% of the inorganic element showed that Ca and Zn reduce the DeNOx activity of the SCR catalyst at low temperature (<300 °C). A loading of phosphorus equals to 1 wt% is needed to observe a similar deactivation at low temperature than the one obtained in presence of 0.24 wt% Ca. The simultaneous presence of Ca and Zn on the catalyst increases the DeNOx deactivation without insofar as the additivity of individual effect is observed. Similarly, introduction of 1 wt% P together with Ca and Zn results in less dramatic consequences to catalyst efficiency than impregnation of P alone. These results were attributed to the formation of phosphate complexes thereby reducing the catalytic deactivation the inorganic elements.

This study is devoted to the evaluation of the impact of both esters' carbon chain length and concentration on sooting propensities of Diesel and Biodiesel surrogates. Soot particles were produced using a steady atmospheric axis-symmetric co-flow diffusion flame burner. Concentrations ranging from 3 to 30% (on molar basis) of methylbutanoate (MB), methyloctanoate (MO) or methyldecanoate (MD) were added to a surrogate Diesel made up of a binary mixture of 70% n-decane and 30% a-methylnaphthalene (alpha-MN). For every considered mixture, the sooting propensity was measured in terms of Yield Sooting Index (YSI) in a methane diffusion flame doped with 3.5% vapor of the mixture. Maps of soot volume fraction in the flame were extracted using a light extinction method (LEM). Soot samples produced along the combustion of surrogate Diesel and Biodiesel fuels were then collected and characterized using physico-chemical techniques, i.e. elemental analysis (CHONS), Thermogravimetric Analysis (TGA), Raman spectroscopy, and Temperature Programmed Oxidation (TPO). Results evidenced that ester functions contained in Biodiesel surrogates reduce soot production. This decrease was more pronounced when the concentration of the oxygenated additive investigated was higher. However, it has been surprisingly determined that YSI decreases when the aliphatic carbon chain of the ester additive is longer. On the other hand, physico-chemical characterizations of the generated model soot revealed that oxygen and soluble organic fraction (SOF) content decreases when the amount of biodiesel surrogate in the fuel in-creases. Nevertheless, no important dissimilarities have been registered in the graphitic structures of the different soot. Finally, the behavior towards oxidation reactivity indicated that the Biodiesel-derived soot were less reactive than the Diesel-derived one.