SOx trapping performances of cuo based silica mesoporous adsorbents for desulfurization of industrial flue gas stream

In the present work, CuO/SBA-15 SOx regenerable adsorbents were elaborated. Synthesis conditions were controlled in order to obtain highly dispersed Cu2+ species assumed to be Cu-O-Si species. Materials were evaluated as SOx adsorbents through multicycle adsorption/regeneration experiments. Their performances decrease along cycles due to copper species sintering and there is an optimal copper loading for a maximal SOx adsorption efficiency. Please click Additional Files below to see the full abstract

SOx trapping performances of cuo based silica mesoporous adsorbents for desulfurization of industrial flue gas stream

In the present work, CuO/SBA-15 SOx regenerable adsorbents were elaborated. Synthesis conditions were controlled in order to obtain highly dispersed Cu2+ species assumed to be Cu-O-Si species. Materials were evaluated as SOx adsorbents through multicycle adsorption/regeneration experiments. Their performances decrease along cycles due to copper species sintering and there is an optimal copper loading for a maximal SOx adsorption efficiency. Please click Additional Files below to see the full abstract

Activated carbon prepared by physical activation of olive stones for the removal of NO2 at ambient temperature

International audienceActivated carbon was prepared from olive stones by physical activation using water vapor at 750°C. Textural, morphology and surface chemistry characterizations were achieved (nitrogen adsorption, SEM, FTIR and TPD–MS). NO2 adsorption was performed for different inlet gas compositions and temperatures. NO2 may adsorb directly on the oxygenated surface groups, and can also be reduced to NO. Therefore, a second NO2 molecule adsorbs on the oxygen left on the carbon surface. TPD performed after NO2 adsorption showed the presence of various surface groups. The adsorption capacity was about 131mg/g, which is higher than with several activated carbon prepared from classical lignocellulosic biomass. NO2 reduction into NO decreased with increasing the inlet oxygen concentration. In contrast, a slight decrease in the NO2 adsorption capacity was observed with increasing temperature. It seems that the activated carbons prepared from olive stones by steam activation could be used as efficient adsorbents for NO2 removal

First step towards understanding the behavior of oxygenated polycyclic aromatic compounds (O-PACs) in soils and groundwater

National audienceObjectives: the aim of this study is to assess O-PAC migration in groundwater in order to know if they could form large contamination plumes in groundwater and therefore trigger a risk for sensitive targets such as drinking water wells. Innovative nature of the proposed topic: O-PAC migration in groundwater and parameters controlling their behavior in soils have never been assessed whereas it is well established in literature that these compounds are toxic, persistent and always present in soils of PAH contaminated sites. Abstract Oxygenated Polycyclic Aromatic Compounds (O-PACs) are toxic, persistent, highly leachable and often abundant at PAH contaminated sites. Furthermore, many studies have proven that O-PACs could be formed during and after the application of some remediation techniques on PAH contaminated sites1,2. However, in contrast to the 16 US EPA PAHs classified as priority pollutants and due to the lack of regulations and data regarding their behavior in soils, O-PACs are not included in health risk assessment studies and monitoring programs of PAH contaminated sites. However, these aromatic compounds could as well have an impact and contribute to the risk for human beings and the Environment. This study constitutes an important step in the process of understanding the transfer of these compounds within the soil system and in determining the related parameters that could affect their behavior. Two PAH/O-PAC couples were chosen for this study: fluorene/fluorenone (FLU/FLUone) and acenaphthene/dibenzofuran (ACE/DBFUR). These compounds were primarily selected regarding their available data, the possibility of their laboratory manipulation as well as the similarity in their molecular structures. Sorption isotherms onto a non-contaminated soil were individually determined using controlled batch experiments for all four compounds. Effects of ionic strength and liquid to solid ratio (L/S) on the sorption of FLU and FLUone were furthermore investigated through controlled batch experiments. For both O-PACs and PAHs, experimental data showed that the sorption kinetics were designated by the occurrence of two distinct phases. A fast-initial phase followed by a second much slower sorption process. Sorption equilibrium was achieved within less than 24 hours of mixing while no degradation of the studied compounds was observed. For all studied compounds and in all experimental conditions, linear sorption models best fit the isotherm data. Results revealed that ACE and DBFUR were similarly adsorbed onto the soil where the values of organic carbon-water partition coefficient (Koc) were 1184 and 1153 L/kg, respectively. In the same experimental conditions, Koc of FLU (1931 L/kg) was higher than that of FLUone (1355 L/kg), showing a smaller affinity of FLUone towards the solid phase. Furthermore, decreasing the L/S ratio from 100 L/kg to 50 and 30 L/kg, increased the sorption of FLUone onto the soil by 64 and 77% respectively, while the sorption of FLU was slightly increased by 13 and 31% respectively. Moreover, increasing the ionic strength of the aqueous phase by a factor of 6 favored 2 the sorption of FLUone by 62% while the sorption of FLU slightly decreased by 13%. These results provided meaningful first information regarding O-PAC behavior in soils: highly soluble O-PACs such as FLUone could easily migrate in groundwater, form larger contamination plumes than PAHs and reach drinking water wells. In addition, the difference in PAH and O-PAC behavior when decreasing the L/S ratio and increasing the ionic strength is a first hint that mechanisms responsible for O-PAC fate and transport in soils could be different than the ones responsible for PAH retention in soils. Further studies are in progress at different scales (lab and field scales) in order to better understand the migration potential of O-PACs

Study of the performances of an oxygen carrier : experimental investigation of the binder's contribution and characterization of its structural modifications.

International audienceThe aim of this work is to investigate the contribution of the binder (NiAl2O4) on the performances of the oxygen carrier NiO/NiAl2O4. To this purpose, oxidation/reduction cycles have been performed in a fixed bed reactor using CO as a fuel. The results reveal that the binder can react with the fuel to form CO2, and that its total reduction capacity increases with temperature. XRD characterizations performed on the binder (on the fresh and after several cycles) show a shift of the diffraction peaks of NiAl2O4 toward the ones of γ-alumina, which can be attributed to a progressive decomposition of NiAl2O4 to alumina and NiO

CuO supported on COK-12 and SBA-15 ordered mesoporous materials for temperature swing SOx adsorption

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 °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 °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