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Palladium has been widely served as the separation material in the hydrogen isotope separation process on account of its unique hydrogenation characteristics. To reduce Pd pulverization effect and improve the gas flow rate, Pd–Al 2 O 3 (Pd deposited on Al 2 O 3) is commonly used as the separation material. It is crucial to grasp the hydrogen absorption and desorption thermodynamics and kinetic isotope effect of Pd–Al 2 O 3 material, which favours raising the separation efficiency. In this work, the effect of PdO existing in the fresh Pd–Al 2 O 3 on the thermodynamic character of Pd–Al 2 O 3 –H(D) system and the porous substrate effect on the hydrogen absorption kinetics of Pd–Al 2 O 3 were investigated. It shows that PdO could totally reduce to Pd after primary hydrogen adsorption-desorption, leading to decreased hydrogen absorption capacity. However, it has no effect on the enthalpy and entropy values of Pd–Al 2 O 3 –H (D) system. The kinetic analysis of hydrogen adsorption of Pd–Al 2 O 3 shows that the hydrogen absorption of Pd–Al 2 O 3 could be fitted by Mample model, a special case of the JMAK model, and the interface-controlled model can be deduced. The porous substrate influences the rate of hydrogen adsorption of Pd–Al 2 O 3. The SEM and XRD results show that after 60 hydrogen absorption-desorption cycles, the surface of Pd–Al 2 O 3 pellet has a slight change with a pulverization rate of 3.3 wt%, although the high-strength alumina support can withstand the stress caused by Pd expansion during hydrogen absorption. • PdO existing in the fresh Pd–Al 2 O 3 could reduce to Pd after primary activation. • After PdO completely reduced to Pd, it has no effect on ΔH and ΔS of Pd–H system. • The porous substrate influences the rate of hydrogen adsorption of Pd–Al 2 O 3. [ABSTRACT FROM AUTHOR]

Electron Tomography (ET) is of greatest interest in studying nano- and biological materials since it gives access to 3D morphological, chemical and physical features. Even though ET techniques have been continuously improved in the last decades, they are still limited: lengthy time scales (tens of minutes) are generally needed for the tilt series acquisition prior to the volume reconstruction step. Such long exposures to a relatively intense electron beam lead to large electron doses received by the sample. This may promote extensive irradiation damage in the case of soft materials like polymers and bio-materials when they are not protected through dedicated sample preparation methods, and any tomographic reconstruction will then be meaningless. More importantly, the time constraints drastically limit 3D investigations during dynamic in-situ experiments where the sample rapidly evolves during the acquisition. We present here developments for acquiring tilt series of projections in very short time scales, readily down to a few seconds. After an outlook of possible ways to speed up the data acquisition in the bright field imaging mode (BF-TEM), strategies for the fastest methods in 'step-by-step' and 'continuous tilt' ET will be described. Applications of these procedures are presented on various systems, including metallic Pd nanoparticles deposited on alumina, and soft materials like polymer nanocomposites and biological matter. A special reference is made to fast operando nano-tomography performed on nanomaterials during their dynamic evolution. The feasibility of fast ET is exemplified by a calcination study of Pd catalysts supported by SiO 2 at 400 °C and 500 °C under 4 mbar H 2 in a dedicated Environmental Transmission Electron Microscope (ETEM). Unlabelled Image • Fast image acquisition for Electron Tomography (ET) can take only a few seconds. • A continuous rotation of the sample allows relevant and fast acquisition for ET. • Fast ET is possible under gas and temperature conditions in-situ in a ETEM. • Repeated acquisitions on the same object allow to follow its evolution in operando. • The resistance to sintering of Pd@SiO 2 nanocatalyst is quantified in situ in 3D. [ABSTRACT FROM AUTHOR]

Abstract: Separation or purification of tritium isotopes is one of the key technologies in ITER. A set of frontal displacement chromatography (FDC) device was designed and constructed for hydrogen isotopes separation using palladium loading on/in alumina (Pd–Al2O3) as the separation material. The hydrogen isotopes separation experiments were carried out. It was found that deuterium abundance of the product was up to 98.5% and the average separation factor was as high as 64, under the condition of 273 K column temperature and 15 mL(NTP)/min flow rate, for a feed gas of 5%H2-5%D2-90%Ar. The deuterium recovery ratio was 42% in this separation test. The results showed that the separation performance of our FDC device was good by using Pd–Al2O3 as separation materials, and it suggested considerable potential for the applicability of FDC in hydrogen isotopes separation. [Copyright &y& Elsevier]

As an alternative to previously developed catalytic FeCrAlloy fibre mat burners based on perovskite catalysts, new catalytic burners have been developed based on Pd catalyst on lantana-stabilised Al2O3 and different fibre structures (NIT100A, NIT100S and NIT200S by ACOTECH NV). All development steps are considered, shifting from catalyst preparation (based on combustion synthesis of γ-Al2O3) to the optimisation of lantana and Pd loadings, from the definitions of the best catalyst-deposition conditions (washcoating) to the catalytic burners performances, determined in an ad hoc developed combustion chamber. The results show almost half pollutants emissions and better performance compared to various non-catalytic counterparts, especially as far as CO and NOx emissions are concerned. Some flame instability problems were though registered, especially for one of the catalytic burner mattresses employed, at low specific power inputs and excesses of air (<375 kW/m2 and <12%, respectively). Further, PdO/Pd transition is shown to influence the dynamic behaviour of the catalytic burners. [Copyright &y& Elsevier]

• Pd is a potential catalyst for end-of-pipe treatment of N 2 O. • Removal of chemisorbed H 2 O on Al 2 O 3 leads to improved Pd dispersion. • Increased dispersion leads to increased activity for N 2 O decomposition. • Co-fed reductant reduces N 2 O total decomposition temperature from 550 to 350 °C. • Benefit of well-dispersed Pd outweighs poisoning effect of residual chloride. The catalytic activity of Pd/γAl 2 O 3 for N 2 O decomposition was found to be highly dependent on the preparation methodology and the number of reaction cycles. Chloride species on the surface of a 2.6 wt. % Pd-Al 2 O 3 catalyst prepared by wet impregnation were identified as inhibiting the activity. Multiple reaction cycles were shown to remove these species, and a subsequent increase in activity was observed; 10.3 mol N2O h−1 kg cat −1 in the first use, increased to 28.7 mol N2O h−1 kg cat −1 on the fourth use both at 550 °C. Additionally, removal of physisorbed water from the support prior to metal deposition increased the thermal stability of Pd nanoparticles and increased the catalyst activity. Catalysts were subsequently prepared using a deposition technique with an increased concentration of Cl- ions resulted in increased Pd-Cl species in the final catalyst and the catalytic activity was consequently increased due to the improved control of Pd particle size. [ABSTRACT FROM AUTHOR]