Zn induced surface modification of stable goethite nanoparticles for improved regenerative phosphate adsorption

Iron oxide-based adsorbents showed potential to reach ultra-low phosphorus (P) concentrations to prevent eutrophication and recover P. High affinity, high capacity at low P concentrations (<1 mg L⁻¹), good stability, and reusability of the adsorbent are key factors for economic viability. In this study, nanoparticles of goethite...

Tuning stability of titania-supported Fischer-Tropsch catalysts: Impact of surface area and noble metal promotion

Cobalt oxidation is a relevant deactivation pathway of titania-supported cobalt catalysts used in Fischer-Tropsch synthesis (FTS). To work towards more stable catalysts, we studied the effect of the surface area of the titania support and noble metal promotion on cobalt oxidation under simulated high conversion conditions. Mössbauer...

Effect of goethite doping using elements with different preferential oxidation states for improved reversible phosphate adsorption

Phosphorus (P) removal from freshwater bodies to ultra-low concentrations is fundamental to prevent eutrophication, while its recovery is necessary to close the P usage cycle. Iron oxide-based adsorbents seem promising candidates, being abundant, cheap, and easy to synthesize compounds, with good affinity for P. Affinity is the key parameter...

FeOOH and (Fe,Zn)OOH hybrid anion exchange adsorbents for phosphate recovery: A determination of Fe-phases and adsorption–desorption mechanisms

Hybrid anion exchange adsorbents (HAIX) seem promising to prevent eutrophication and recover phosphate (P). HAIX consist of an anion exchange resin (AIX) backbone, promoting anion physisorption (outer-sphere complex), impregnated with iron (hydr)oxide nanoparticles (NPs), for selective P chemisorption (inner-sphere complex). In this work, for...

Revealing Active Sites and Reaction Pathways in Methane Non-Oxidative Coupling over Iron-Containing Zeolites

Non-oxidative coupling of methane is a promising route to obtain ethylene directly from natural gas. We synthesized siliceous [Fe]zeolites with MFI and CHA topologies and found that they display high selectivity (>90 % for MFI and >99 % for CHA) to ethylene and ethane among gas-phase products. Deactivated [Fe]zeolites can be regenerated...

Copper promotion of chromium-doped iron oxide water-gas shift catalysts under industrially relevant conditions

Copper promotion of chromium-doped iron oxide prepared via co-precipitation for high-temperature water–gas shift (WGS) catalysis is investigated. Low-temperature Mössbauer spectra demonstrate that copper doping delays hematite (α-Fe₂O₃) formation in the fresh catalyst, favoring the formation of small crystallites of...

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...

From Structure to Function: Understanding Synthetic Conditions in Relation to Magnetic Properties of Hybrid Pd/Fe-Oxide Nanoparticles

Heterostructured magnetic nanoparticles show great potential for numerous applications in biomedicine due to their ability to express multiple functionalities in a single structure. Magnetic properties are generally determined by the morphological characteristics of nanoparticles, such as the size/shape, and composition of the nanocrystals....

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....

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...

Effect of pore size distribution on iron oxide coated granular activated carbons for phosphate adsorption – Importance of mesopores

Adsorption is often suggested for to reach very low phosphate levels in municipal wastewater effluent and even to recover phosphate. Adsorbent performance is usually associated with surface area but the exact role of the pore size distribution (PSD) is unclear. Here, we show the effect of the PSD on phosphate adsorption. Granular activated...