Structure and bonding in TiNiSi type LaMgSnH intermetallic hydride

The work was aimed on reaching a better understanding of the effect of magnesium as a component of the hydride-forming LaMgSn intermetallic compound crystallising with the orthorhombic TiNiSi type of structure on the hydrogenation behaviours, crystal structure and bonding interactions with hydrogen. The LaMgSn structure is significantly...

Elucidating deactivation of titania-supported cobalt Fischer-Tropsch catalysts under simulated high conversion conditions

The study of titania-supported cobalt nanoparticles is relevant for industrial Fischer-Tropsch synthesis (FTS). Herein, we report about various deactivation pathways of cobalt supported on P25 titania (cobalt loading 2–8 wt%) under simulated high conversion conditions using in situ Mössbauer spectroscopy. A fraction of metallic cobalt was...

Manganese as a structural promoter in silica-supported cobalt Fischer-Tropsch catalysts under simulated high conversion conditions

Understanding the deactivation mechanism of cobalt-based Fischer-Tropsch catalysts is of significant practical importance. Herein, we explored the role of manganese as a structural promoter on silica-supported cobalt nanoparticles under simulated high CO conversion conditions, i.e., high relative humidity. The structural changes in cobalt...

Magnetoelastic transition and negative thermal expansion of Fe₂Hf_0.83Ta_0.17 ribbons

In this work, the magnetocaloric effect and negative thermal expansion in melt-spun Fe₂Hf_0.83Ta_0.17 Laves phase alloys were studied. Compared to arc-melted alloys, which undergo a first-order magnetoelastic transition from the ferromagnetic to the antiferromagnetic phase, melt-spun alloys exhibit a second...

Effect of Co and Ni doping on the structure, magnetic and magnetocaloric properties of Fe-rich (Mn,Fe)₂(P,Si) compounds

The effect of Co and Ni doping on the structure, magnetic and magnetocaloric properties of Fe-rich (Mn,Fe)₂(P,Si) compounds was studied. With increasing Co and Ni content, both the Curie temperature (T_c) and the thermal hysteresis (ΔT_hys) decreased, whereas the hexagonal P-62 m crystal structure was maintained...

Substituting Chromium in Iron-Based Catalysts for the High-Temperature Water-Gas Shift Reaction

A set of doped iron oxides (chromium, aluminum, gallium, indium, manganese, zinc, niobium) were prepared by a one-step coprecipitation/calcination approach evaluated for their WGS activity under industrially relevant conditions and characterized in detail. The WGS activity after ageing the doped catalyst for 4 days at 25 bar follows the order...

Efficient formation of vivianite without anaerobic digester: Study in excess activated sludge

It was recently discovered that vivianite (Fe₃(PO₄)₂.8H₂O) could be magnetically extracted from digested activated sludge which opened a new route for phosphorus recovery (Wijdeveld et al. 2022). While its formation in digested sludge is regularly reported, it is not yet studied for fresh,...

Sintering and carbidization under simulated high conversion on a cobalt-based Fischer-Tropsch catalyst; manganese oxide as a structural promotor

The commercial application of cobalt-based Fischer-Tropsch synthesis (FTS) suffers from catalyst deactivation. One of the main deactivation mechanisms under industrial conditions is sintering. In this work, we explored the role of manganese oxide as a structural promoter against sintering in a carbon nanofiber supported cobalt model catalyst....

Role of surface carboxylate deposition on the deactivation of cobalt on titania Fischer-Tropsch catalysts

Operando spectroscopic techniques (Diffusive Reflective Infrared Fourier-Transform and Mössbauer emission spectroscopy) were combined to investigate the role of oxygenates deposition on deactivation of cobalt on titania Fischer-Tropsch catalysts at high pressure. Clear formation of carboxylates was seen for catalysts prepared via both...

The role of chromium in iron-based high-temperature water-gas shift catalysts under industrial conditions

Chromium promotion of iron oxide based water-gas shift (WGS) catalysts prepared via co-precipitation/calcination was investigated. Mössbauer spectroscopy and XRD evidence that chromium is incorporated in the calcined hematite (α-Fe₂O₃) precursor irrespective of the doping level (0−12 wt.%). CO-TPR shows chromium delays...

Full-scale increased iron dosage to stimulate the formation of vivianite and its recovery from digested sewage sludge

The recovery of phosphorus from secondary sources like sewage sludge is essential in a world suffering from resources depletion. Recent studies have demonstrated that phosphorus can be magnetically recovered as vivianite (Fe(II)₃(PO₄)₂∗8H₂O) from the digested sludge (DS) of Waste Water Treatment...

Tuning the magneto-elastic transition of (Mn,Fe,V)₂(P,Si) alloys to low magnetic field applications

The first-order magneto-elastic transition in the Mn–Fe–P–Si alloys can be tailored by vanadium substitution. Alloys with a suitable V substitution provide an excellent magnetocaloric effect with minor hysteresis in low magnetic fields up to 1.2 T. Mössbauer measurements show that the hyperfine field is reduced by V substitution. Neutron...

Magnetic separation and characterization of vivianite from digested sewage sludge

To prevent eutrophication of surface water, phosphate needs to be removed from sewage. Iron (Fe) dosing is commonly used to achieve this goal either as the main strategy or in support of biological removal. Vivianite (Fe(II) ₃ (PO ₄ ) ₂ * 8H ₂ O) plays a crucial role in capturing the phosphate, and...

The electrochemical sodiation of sb investigated by Operando X-ray absorption and ¹²¹ sb mössbauer spectroscopy: What does one really learn?

In this study, we want to highlight the assets and restrictions of X-ray absorption spectroscopy (XAS) and Mössbauer spectroscopy for investigating the mechanism of the electrochemical reaction of antimony electrode materials vs. Na. For this, operando XAS was carried out during the first one and a half cycles, and the whole set of measured...

Vivianite as an important iron phosphate precipitate in sewage treatment plants

Iron is an important element for modern sewage treatment, inter alia to remove phosphorus from sewage. However, phosphorus recovery from iron phosphorus containing sewage sludge, without incineration, is not yet economical. We believe, increasing the knowledge about iron-phosphorus speciation in sewage sludge can help to identify new routes...

Mössbauer spectroscopy, magnetization, magnetic susceptibility, and low temperature heat capacity of α-Na₂NpO₄

The physical and chemical properties at low temperatures of hexavalent disodium neptunate α-Na₂NpO₄ are investigated for the first time in this work using Mössbauer spectroscopy, magnetization, magnetic susceptibility, and heat capacity measurements. The Np(VI) valence state is confirmed by the isomer shift value of the...

Complex Magnetic Phenomena in Rare Earth Intermetallic Compounds