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Yttrium-stabilized zirconia (YSZ) has been extensively studied as an electrolyte material for solid oxide fuel cells (SOFC) but its performance in heterogeneous catalysis is also the object of a growing number of publications. In both applications, oxygen activation on the YSZ surface remains the step that hinders utilization at moderate temperature. It was demonstrated by oxygen isotope exchange that a dual catalyst bed system consisting of two successive LaMnO3 and YSZ beds without intimate contact drastically enhances oxygen activation on the YSZ surface at 698 K. It can be concluded that LaMnO3 activates the triplet ground-state of molecular oxygen into a low-lying singlet state, thereby facilitating the activation of the O2 molecule on the YSZ oxygen vacancy sites. This phenomenon is shown to improve the catalytic activity of the LaMnO3-Pd/YSZ system for the partial oxidation of methane. [ABSTRACT FROM AUTHOR]

The Front Cover shows the oxidation of methane on lanthanum manganate and yttrium‐stabilized zirconia‐supported Pd dual‐bed catalyst system. In their Full Paper, Richard et al. focus on the association of manganese perovskite (LaMnO3) and yttrium‐stabilized zirconia (YSZ) materials for total methane oxidation. A significant enhancement of methane abatement activity is achieved over low loading palladium (0.2 wt. % Pd) supported YSZ catalyst in a promising LaMnO3+YSZ dual bed system, resulting in a significant increase of the oxidation rate with a correlative decrease of the light‐off temperature of 65 °C. It is concluded that LaMnO3 upstream activates the triple ground‐state of molecular oxygen into a low‐lying singlet state improving the oxygen activation on the lacunary YSZ surface. Additionally, a Mars‐Van‐Krevelen mechanism was demonstrated at 425 °C using labeled 18O2 exchange technical. More information can be found in the Full Paper by Richard et al. on page 1921 in Issue 11, 2016 (DOI: 10.1002/cctc.201501398). [ABSTRACT FROM AUTHOR]

Highlights: [•] LaMnO3 were synthesized by three different methods, citrate sol–gel, glycine combustion and co-precipitation. [•] LaMnO3 synthesized by citrate sol–gel exhibited the best catalytic performance for toluene oxidation. [•] No by-products were formed but only CO2 and H2O. [•] Specific surface area, reducibility and surface adsorbed oxygen were the main parameters. [•] Apparent activation energies of all samples correlated well with their catalytic activities. [ABSTRACT FROM AUTHOR]

Abstract: Catalytic oxidation of vinyl chloride (VC) emission was carried out over LaMnO3 and La0.8A0.2MnO3 (A=Sr, Mg and Ce) perovskite oxides synthesized via co-precipitation method. Numerous characterization techniques were performed to investigate the relationship between the catalytic performance and its physicochemical properties. It was found that the partial substitution of lanthanum by cerium and magnesium had a positive effect on the catalytic performance for VC oxidation, whereas strontium involved a negative effect. Under the reaction conditions (VC concentration=1000ppm, GHSV=15,000h−1), the overall catalyst ranking in terms of the catalytic activity from the best to the worst performance was La0.8Ce0.2MnO3 >La0.8Mg0.2MnO3 >LaMnO3 >La0.8Sr0.2MnO3 with regard to the temperature of T50 and T90. The Ce-doped perovskite catalyst showed the optimum catalytic performance due to its higher specific surface area and its ability to promote the low-temperature reducibility. Moreover, as the active species, the increased surface adsorbed oxygen was also responsible for the enhancement of the catalytic performance. [Copyright &y& Elsevier]

Abstract: The LaMnO3 and LaB0.2Mn0.8O3 (B=Co, Ni, Fe) perovskite-type oxides were prepared by the conventional co-precipitation method and studied as catalysts for the oxidation of vinyl chloride emission in the temperature range of 50–350°C. Their physicochemical properties were characterized by ICP-AES, N2 adsorption, XRD, H2-TPR, O2-TPD and XPS. Catalytic performances were evaluated for the oxidation of 1000ppm of VC in air at a GHSV of 15,000h−1. The substituted LaB0.2Mn0.8O3 samples showed higher catalytic activity than pure LaMnO3. Characterization results revealed that the catalytic activity of the perovskite oxides was greatly related to the low-temperature reducibility of the B site and the amount of adsorbed oxygen species and vacancies on the surface. The surface adsorbed oxygen species played a key role in the catalytic reaction and oxygen vacancies promoted the oxygen mobility. A reaction mechanism of vinyl chloride oxidation over LaMnO3-based perovskite oxides was proposed. [Copyright &y& Elsevier]

Abstract: The selective catalytic reduction of NO by n-decane (C10H22-SCR), with or without water (1.5vol.%), has been studied over sulphated titania catalysts (∼2wt% S). Such sulphated materials have been explored as candidates for HC-SCR by decane with process temperatures >600°C. The nature of the functional groups from residual reaction products and the thermal stability of sulphated compounds were characterized by mass spectroscopy, FTIR analysis and temperature programmed desorption experiments. It was observed that hydrocarbons (C x H y ), aldehyde (RCHO), acid (RCOOH), ester (RCOOR) and primary and secondary amine (RNH2, R2NH) functional groups were present at the catalyst surface. For the sample not tested under HC-SCR reaction, the sulphate compounds (SO4 2−, SO3 2−) were stable up to 600°C under He-TPD whereas for samples tested under the HC-SCR reaction, sulphate species were released above 400°C. This might be due to the exothermic oxidation reaction of deposited carbon compounds, characterized by ex situ analysis, with oxygen supplied by the sulphated support. This effect was confirmed by mixing the catalyst with soot particles. Lastly, we propose a reaction scheme for the HC-SCR of NO by decane over sulphated titania. [Copyright &y& Elsevier]

Abstract: In recent years planar yttria-stabilized zirconia (YSZ) based electrochemical gas sensors for automotive exhaust applications have become a major source of interest. The present work aims to develop a sensor for industrialisation. For this reason planar YSZ-based electrochemical sensors using two metallic electrodes (platinum and gold) were fabricated using screen-printing technology and tested in a laboratory test bench for different concentrations of pollutant gas such as CO, NO, NO2 and hydrocarbons in oxygen rich atmosphere. It was furthermore shown that the selectivity towards NO x could be highly reinforced by deposing a catalytic filter consisting of 1.7–4.5wt.% Pt dispersed on alumina directly on the sensing elements. This filter was characterized by the use of SEM, TPD and XRD. [Copyright &y& Elsevier]

The intensification of pharmaceutical use globally has led to an increase in the number of water bodies contaminated by drugs, and an effective strategy must be developed to address this issue. In this work, several biochars produced from Miscanthus straw pellets (MSP550, MSP700) and wheat straw pellets (WSP550, WSP700) at 550 and 700°C, respectively, were selected as adsorbents for removing various pharmaceuticals, such as pemetrexed (PEME), sulfaclozine (SCL), and terbutaline (TBL), from the aqueous phase. The biochar characterizations (physicochemical properties, textural properties, morphological structures, and zeta potentials) and adsorptive conditions (contact times, temperatures, and pH effect) were investigated. The infrared and Raman spectra of biochars before and after pharmaceutical adsorption, as well as quantum chemical computations, were carried out to explore the adsorption mechanisms. The results showed that the general adsorption abilities of biochars for pharmaceuticals were in the order of WSP700 > MSP700 > MSP550 > WSP550. Both the higher drug concentration and higher temperature improved biochar adsorption. By decreasing the pH, the adsorption amounts increased for PEME and SCL. However, TBL exhibited the best adsorption at pH 7, whereas a weakening of affinity occurred at lower or higher pH values. Electrostatic interactions and hydrogen bonding were the main adsorptive mechanisms between all biochars and pharmaceuticals. π-π interactions played a role in the adsorption process of low-temperature-prepared biochars (MSP550 and WSP550). This work can provide new insights into the control of pharmaceuticals from water with low-cost adsorbents. PRACTITIONER POINTS: Use of biochars for pharmaceuticals removal from aqueous phase. Characterization of biochars : physical and chemical properties, textural and surface properties. Simulation calculation for characterization of pharmaceuticals. Kinetic studies of pharmaceuticals adsorption on biochars. DRIFTS and Raman analysis for the understanding of adsorption process., (© 2023 Water Environment Federation.)

In Earth's atmosphere, the surface tension of sub-micron aerosol particles is suspected to affect their efficiency in becoming cloud droplets. But this quantity cannot be measured directly and is inferred from the chemical compounds present in aerosols. Amphiphilic surfactants have been evidenced in aerosols but experimental information on the surface properties of their mixtures with other aerosol components is lacking. This work explores experimentally the surface properties of aqueous mixtures of amphiphilic surfactants (SDS, Brij35, TritonX100, TritonX114, and CTAC) with inorganic salts (NaCl, (NH 4 ) 2 SO 4 ) and soluble organic acids (oxalic and glutaric acid) using pendant droplet tensiometry. Contrary to what could be expected, inorganic salts and organic acids systematically enhanced the efficiency of the surfactants rather than reduced it, by further lowering the surface tension and, in some cases, the CMC. Furthermore, all the mixtures studied were strongly non-ideal, some even displaying some synergism, thus demonstrating that the common assumption of ideality for aerosol mixtures is not valid. The molecular interactions between the mixture components were either in the bulk (salting out), in the mixed surface monolayer (synergy on the surface tension) or in the micelles (synergy on the CMC) and need to be included when describing such aerosol mixtures., (© 2023. The Author(s).)

A series of Y-modified cobalt oxides with various Y/(Co+Y) molar ratios (0.25 %, 0.5 %, 1 %, 3 % and 5 %) were prepared to study the effect of Y content on toluene and propane combustion. The characterization of the catalysts revealed that proper Y incorporation resulted in smaller crystallite sizes, larger specific surface areas, more oxygen vacancies and weaker Co-O bonds. As such, the Y-modified Co 3 O 4 showed enhanced low-temperature reducibility, boosted oxygen mobility and better catalytic activity. However, excess Y (> 1 %) aggregates on the surface of Co 3 O 4 and forms yttrium carbonate species, hindering the catalyst activity. A volcano-type relationship between the Y content and the catalytic activity was established. The optimal catalyst 1 % Y-Co (with Y/(Co+Y) molar ratio of 1 %) exhibited toluene oxidation rate of 24 nmol g -1 s -1 at 220 °C and propane oxidation rate of 69 nmol g -1 s -1 at 180 °C. Besides, 1 % Y-Co presented perfect cycling stability and long-term durability in propane oxidation. Regarding its low cost, high efficiency and good stability, 1 % Y-Co is a promising catalyst for the practical elimination of hydrocarbon emissions., (Copyright © 2022 Elsevier B.V. All rights reserved.)

A set of supported Co 3 O 4 catalysts have been designed and prepared to study the effect of textural characteristics and Brønsted acid sites concentration of MWW zeolite support, as well as cobalt loading on catalyst activity. Detailed characterization of the catalysts with a thorough study on their performance in the total oxidation of toluene and propane revealed that MCM-22 is the optimal support and that increasing Si/Al and decreasing external surface of MCM-22 positively affect the activity of supported Co 3 O 4 catalysts, which is determined by their low-temperature reducibility. The activity of the Co/MCM-22 catalysts increased with cobalt content (5-20 wt %), consistent with enhancing the amount of low-temperature reducible Co 3 O 4 . The optimized catalyst containing 20% Co supported on dealuminated MCM-22 presented high turnover frequency (TOF) values in both toluene (2.6 × 10 -5 s -1 at 270 °C) and propane (3.9 × 10 -5 s -1 at 215 °C) oxidation and was characterized by outstanding cycling stability, long-term durability, water tolerance, and sintering resistance.

The present study analyzes the effect of parameters that determine the use of the zeolite 5A as collector medium in passive flux samplers (PFS) developed to estimate N 2 O emissions from livestock buildings. The study analyzes the mass of N 2 O collected on the zeolite 5A as a function of gas flow rate (40 and 130 ml/min), inlet mass of N 2 O to the PFS (from 7 to 84 μg), adsorbent mass (4 and 13.6 g), length of the adsorbent bed (1.9 and 10.9 cm), and inlet N 2 O concentration (0.6 and 2 ppmv). The mass of N 2 O collected on the zeolite 5A ranged from 1.24 to 6.19 μg of N 2 O/g of adsorbent, which was mainly affected by inlet N 2 O concentration and mass of adsorbent contained in the PFS. The mass of N 2 O collected presented a significant relationship with the inlet N 2 O concentration and the adsorbent bed. Tests were performed using PFS in a laboratory farm under semi-real conditions. It was found that at sampling time of 1.5 h, the accuracy and precision of PFS was appropriate. Under evaluated conditions, a maximum variation between PFS and direct detection of around 12% was estimated.

Yttrium-stabilized zirconia (YSZ) has been extensively studied as an electrolyte material for solid oxide fuel cells (SOFC) but its performance in heterogeneous catalysis is also the object of a growing number of publications. In both applications, oxygen activation on the YSZ surface remains the step that hinders utilization at moderate temperature. It was demonstrated by oxygen isotope exchange that a dual catalyst bed system consisting of two successive LaMnO3 and YSZ beds without intimate contact drastically enhances oxygen activation on the YSZ surface at 698 K. It can be concluded that LaMnO3 activates the triplet ground-state of molecular oxygen into a low-lying singlet state, thereby facilitating the activation of the O2 molecule on the YSZ oxygen vacancy sites. This phenomenon is shown to improve the catalytic activity of the LaMnO3-Pd/YSZ system for the partial oxidation of methane., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)