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H-ZSM-5 and H-*BEA zeolites were hydrothermally synthesized with different Si/Al ratios (∼12 to ∼40). The physico-chemical properties of the resulting materials were fully characterized by several techniques (NMR, BET, PXRD, and pyridine thermal desorption followed by infrared spectroscopy). To assess the effect of the zeolite type and Si/Al ratio on sample reactivity, the charge separation processes between the zeolite framework and the adsorbed trans-stilbene (t-St) molecule were investigated by UV-visible diffuse reflectance and FT-Raman spectroscopy. The UV-visible absorption spectra obtained after t-St adsorption show a clear difference depending on the zeolite type. It appears that the radical cation resulting from t-St spontaneous ionization is more stabilized in the MFI-type framework than in the *BEA topology. However, the amount and stability of the electron–hole pair resulting from the radical cation evolution to a charge transfer complex are more important in the *BEA zeolite. On the basis of the experimental results and physico-chemical properties of the sample, we found that the radical cation and the electron–hole stabilities are strongly dependent on the amount of hexacoordinated aluminum (Al(VI)) and more precisely on their environment, i.e. the distance between Brønsted sites and strong Lewis sites or Brønsted Strong Lewis Pairs (BSLPs). [ABSTRACT FROM AUTHOR]

H-ZSM-5 zeolite (Si/Al = 19.3) was hydrothermally synthesized. Alkaline and/or acid post-synthesis treatments were carried out to give rise to an interconnected mesoporous volume. The desilication treatment parameters have been tuned (temperature, organic base addition) to obtain a series of samples with increasing mesoporous volume and a constant number of acid sites. The physico-chemical properties of the resulting materials were fully characterized by many techniques (NMR, BET, PXRD, and pyridine thermal desorption followed by infrared spectroscopy). To assess the effect of post-treatments on sample reactivity, the charge separation processes between the zeolite framework and adsorbed trans-stilbene (t-St) molecule were investigated by UV-visible diffuse reflectance. The spectra obtained after t-St adsorption show clear differences depending on the applied post-treatments. It appears that the desilication treatments performed without acidic washing highly stabilize the radical cation resulting from the t-St spontaneous ionization. In contrast, by applying acidic washing after desilication, the ionization process becomes significantly weaker. The results show that the proportion of strong Lewis acid sites in the vicinity of Brønsted sites named Brønsted Strong Lewis Pairs (BSLP), are responsible for the amount of radical cations observed in the different samples. More precisely, it exists an optimal proportion of BSLP to achieve a high ionization rate. On the basis of the experimental results a mechanism for the formation of the t-St radical cation and the charge transfer complex (CTC) is proposed. [ABSTRACT FROM AUTHOR]

High pressure intrusion–extrusion of concentrated solutions of sodium salts in a pure-silica MFI-type zeolite (Silicalite-1) was studied for potential applications in mechanical energy absorption and storage. It was discovered that the anion nature has a drastic influence on the behavior and the energetic performances of “Silicalite-1 – concentrated Na+X− solution” systems, where X = Cl−, Br−, I−, NO2−, NO3−, ClO4− and CrO42−. In the case of NaNO2, NaClO4, Na2CrO4, and NaI a combination of bumper and shock-absorber behaviors with a partial irreversible solution intrusion was observed, whereas a fully reversible spring behavior is demonstrated for the intrusion–extrusion of NaBr, NaCl and NaNO3 solutions. In comparison with water, the intrusion pressure increases for all the solutions except for NaClO4 one. The irreversibility of intrusion decreases with a dilution rate, and the behavior of the corresponding systems with diluted solutions becomes very close. The variation of the system behavior and intrusion pressure values can be related to a different affinity of the corresponding anions for the pores of Silicalite-1. The samples before and after intrusion–extrusion experiments were characterized using several structural and physicochemical methods (XRD, TGA, solid-state NMR, and N2 physisorption), but no significant structural difference was observed. [ABSTRACT FROM AUTHOR]

The energetic performances of pure silica ITH-type zeolites were studied by high pressure intrusion–extrusion in water and LiCl aqueous solutions at different concentrations. When pure water was intruded, a bumper behavior was exhibited with an intrusion pressure of 82 MPa and an absorbed energy of 6.6 J g−1. Changing the intruded liquid from water to LiCl aqueous solutions, an increase of the intrusion pressure was observed with 119, 175 and 280 MPa for 5 M, 10 M and 20 M LiCl aqueous solutions, respectively. The energy that the latter system could absorb (30.8 J g−1) was among the highest ever reported. A change in the behavior with LiCl concentration was also observed. The “ITH-type zeosil–20 M LiCl solution” system demonstrated a combination of bumper and shock-absorber behaviors, whereas a bumper behavior was displayed for water and the other LiCl aqueous solutions. All the zeolite samples were characterized before and after intrusion–extrusion experiments (XRD, SEM, N2 adsorption–desorption, TG and NMR analysis) in order to understand the influence of LiCl concentration on the “zeosil–liquid” system behavior. [ABSTRACT FROM AUTHOR]

In order to study the energetic performances of different “pure silica chabazite–LiCl aqueous solution” systems, intrusion–extrusion experiments were performed under high pressure. Depending on the LiCl concentration in the aqueous medium (0 M, 5 M, 10 M, 20 M), an increase of the stored (4.4, 9.9, 13.5, 24.3 J g−1) and restored (2.6, 8.1, 11.8, 20.5 J g−1) energies are observed. Therefore, compared to the “pure silica CHA–H2O” system, the stored energy is increased by 5.5 times for the “pure silica CHA–20 M LiCl” one. The zeolite samples were characterized (XRD, TG, NMR spectroscopy, N2 adsorption and SEM) before and after the intrusion–extrusion process in order to better understand the influence of the LiCl concentration on the system behavior. [ABSTRACT FROM AUTHOR]

High pressure water and electrolyte solutions intrusion–extrusion experiments in pure-silica *BEA-type zeolite (zeosil β) were performed in order to study the performances of these systems in energy absorption and storage. The “zeosil β–water” system displays a bumper behavior with an intrusion pressure of 53 MPa and an absorbed energy of 8.3 J g−1. For the “zeosil β–LiCl aqueous solutions” systems the intrusion pressure increases with the LiCl concentration to 95, 111 and 115 MPa for 10, 15 and 20 M solution, respectively. However, for concentrations above 10 M, a transformation of the system behavior from bumper to shock-absorber is observed. The zeolite samples were characterized by several structural and physicochemical methods (XRD, TGA, solid-state NMR, N2 physisorption, ICP-OES) before and after intrusion–extrusion experiments in order to understand the influence of the LiCl concentration on the intrusion–extrusion behavior. It is shown that the intrusion of water and LiCl solutions with low concentration leads to the formation of Si-(OSi)3OH groups, whereas no defects are observed under intrusion of concentrated LiCl solutions. A possible mechanism of LiCl solution intrusion based on separate intrusion of H2O molecules and Li(H2O)x+ ions is proposed. [ABSTRACT FROM AUTHOR]

Abstract: This work concerns atmospheric particles (PM 2.5) collected in the surroundings of rural, urban and industrial areas. The investigation zone chosen for the study is Dunkirk (North of France), a highly industrialised city located along the North sea, where various activities are present such as metallurgy, petrol refineries and other chemical companies but also an important city with 210 000 inhabitants and two highly loaded motorways. Comparisons with a rural area were carried out. Physicochemical analysis of particulate matter was undertaken to propose parameters that could be used to distinguish the various sources and also to provide chemical elements for interpretation of future toxicological studies. This paper focuses on both organic and inorganic pollutants: Polycyclic Aromatic Hydrocarbons (PAH), paraffins, Volatile Organic Compounds (VOC), heavy metals and major soluble compounds (anionic and cationic). [Copyright &y& Elsevier]

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Both the performance and regenerability of SO 2 adsorbents made of CuO supported on SBA-15 ordered mesoporous silica were studied for a cyclic DeSOx process under wet and dry conditions. H 2 O vapor decreases the performance of a 16 wt% loading CuO/SBA-15 (16CuO/SBA-15) adsorbent along the adsorption/regeneration cycles performed at 400 °C. Indeed, the SO 2 breakthrough adsorption capacity of this adsorbent after ten adsorption- regeneration cycles under wet conditions (5 vol% of H 2 O) decreases of 61% compared to the SO 2 performance obtained under dry conditions. The impact of the temperature as well as the CuO loading on the performance and regenerability of CuO/SBA-15 sorbents were also investigated under dry and wet conditions. XRD, TEM/EDX, N 2 physisorption characterizations of the adsorbents were performed after the last cycle to correlate the structural and textural properties of the adsorbents and therefore the copper species, with the performance of the adsorbents. Increasing the temperature up to 450 °C with or without water increases the SO 2 adsorption capacity of the 16CuO/SBA-15 adsorbent with higher SO 2 adsorption capacity at 450 °C with water than without water. In the presence of water vapor, the 8CuO/SBA-15 adsorbent presents the highest average loss of SO 2 adsorption capacity at the breakthrough of around 71% when expressed in mg SO 2 / g CuO , compared to the ones obtained with the 16CuO/SBA-15 and the 26CuO/SBA-15 adsorbents. The increase of the CuO loading up to 26 wt%, shows that the contribution of the surface copper active phase highlighted by the desorption curves, decreases significantly for the highest CuO loading under wet conditions. Moreover, with or without water, the highest total SO 2 adsorption capacities obtained after the tenth cycle are observed for the lowest CuO loading (8 wt% of CuO: 547 and 495 mg SO 2 / g CuO without and with H 2 O, respectively). These higher total SO 2 adsorption capacities could be explained by a better CuO phase dispersion on the SBA-15 support, which makes the copper active species more reactive especially with H 2 O. [Display omitted] • SO 2 adsorption capacity of CuO/SBA-15 adsorbents decreases with water vapour at 400 °C. • Blocking of the Cu-based active sites by competitive physisorption of H 2 O and SO 2. • Agglomeration of the CuO active phase is intensified in presence of water vapor. • Increase of the SOx trapping performance with H 2 O at high temperature 450 °C. [ABSTRACT FROM AUTHOR]

• SO 2 adsorption capacity of CuO/SBA-15 greatly increases with NO 2 in gas phase. • CO oxidation catalysed by CuO species. • Partial reduction of NO 2 into NO catalysed by copper oxide. • Reaction SO 2 + NO 2 → SO 3 + NO seems to play a major role in the increased DeSOx performance. • In gas phase: oxidation of SO 2 by NO 2 to form SO 3 is catalysed by copper active sites. SOx (i.e. SO 2 and SO 3) compounds are known to be a major source of atmospheric pollution and to be responsible of adverse effects on the human health and on the environment. To reduce the SOx emissions, numerous abatement technologies were developed and applied. Nowadays, the most attractive one seems to be the process that use a regenerable SOx adsorbent. In this respect, a CuO (15 wt.%)/SBA-15 regenerable type SOx adsorbent has been developed. Under standard conditions (a gaseous mixture of N 2 , SO 2 and O 2), the adsorbent exhibits a stable adsorption capacity around 50 mg SO 2 /g ads along 10 cycles at 400 °C (for a 75 ppm of SO 2 exhaust concentration). The main aim of this work is to study the impact of various regulated pollutants such as CO, CO 2 , NO and NO 2 on the SO 2 adsorption capacity of the CuO (15 wt.%)/SBA-15 adsorbent. In the presence of CO and CO 2 , the SO 2 adsorption performance of the CuO/SBA adsorbent is similar to the one observed under standard conditions. On the other hand, under NO and NO 2 atmosphere, the dynamic and total adsorption capacities of the adsorbent are enhanced up to 25% and no deactivation occurs along the cycles. The increase may be related with the synergetic effect between NO 2 and SO 2 towards the sulphate formation. The CuO/SBA-15 adsorbent before and after multicycle SO 2 adsorption in the presence of regulated pollutants and regeneration under 0.5 vol.% of H 2 have been characterized by XRD and N 2 physisorption. No significant structural and textural change is observed compared to the CuO/SBA-SO 2 adsorbent. [ABSTRACT FROM AUTHOR]

Abstract: Four pure silica zeolites, chabazite (CHA-structure type) and SSZ-23 (STT-structure type) with cage-like structure and silicalite-1 (MFI-structure type) and beta (∗BEA-structure type) with channel structure, were synthesized and fully characterized. Their sorption properties were examined using gravimetric method combined with Grand Canonical Monte Carlo simulations (GCMC). Of particular interest is the large difference in the adsorption rates of n-hexane, p-xylene and acetone observed for these zeosils at 25, 75 and 150°C. As expected, in most cases, a decrease in the adsorption capacity is observed with increasing the molar volume of the used probe molecule and the temperature. An exception is observed for the pure silica CHA-type zeolite due to its small pore size which prevents molecules from entering its porosity. However, at higher temperature, the window size widens slightly and allows n-hexane and acetone, which have kinetic diameter close to the pore opening, to enter easily in chabazite. As a result, for this zeosil, an increase in the adsorption capacity compared to that obtained at 25°C is observed. All these zeosils are promising for technological uses in car exhaust gas decontamination. [Copyright &y& Elsevier]