Effect of gold loading on ceria-zirconia support in total oxidation of VOCs

The zirconia supported CoMo catalysts and the commercial sample CoMo/Al2O3 were characterized by XPS measurements and by testing of activity in the HDS of thiophene at 280 °C and 1 MPa of total pressure. The XPS measurements revealed the better reducibility of molybdenum, higher sulphidability of cobalt and the absence of surface sulphur oxidation in the presence of zirconia support. The surface atomic concentration ratios S/Mo were 1.2 and 2.2 for zirconia and alumina supported catalysts, respectively. The activity of the zirconia supported CoMo catalyst normalized to the overal amounts of active metals was lower than that of the commercial CoMo/Al2O3 catalyst.

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Influence of Alumina Precursor Properties on Cu-Fe Alumina Supported Catalysts for Total Toluene Oxidation as a Model Volatile Organic Air Pollutant

Catalysts ◽

10.3390/catal11020252 ◽

2021 ◽

Vol 11 (2) ◽

pp. 252

Author(s):

Tadej Žumbar ◽

Alenka Ristić ◽

Goran Dražić ◽

Hristina Lazarova ◽

Janez Volavšek ◽

...

Keyword(s):

Surface Characterization ◽

Iron Concentration ◽

Catalytic Performance ◽

Air Pollutant ◽

Molar Ratio ◽

Homogeneous Distribution ◽

Total Oxidation ◽

Alumina Support ◽

Determining Factors ◽

Volatile Organic

The structure–property relationship of catalytic supports for the deposition of redox-active transition metals is of great importance for improving the catalytic efficiency and reusability of the catalysts. In this work, the role of alumina support precursors of Cu-Fe/Al2O3 catalysts used for the total oxidation of toluene as a model volatile organic air pollutant is elucidated. Surface characterization of the catalysts revealed that the surface area, pore volume and acid site concentration of the alumina supports are important but not the determining factors for the catalytic activity of the studied catalysts for this type of reaction. The determining factors are the structural order of the support precursor, the homogeneous distribution of the catalytic sites and reducibility, which were elucidated by XRD, NMR, TEM and temperature programed reduction (TPR). Cu–Fe/Al2O3 prepared from bayerite and pseudoboehmite as highly ordered precursors showed better catalytic performance compared to Cu-Fe/Al2O3 derived from the amorphous alumina precursor and dawsonite. Homogeneous distribution of FexOy and CuOx with defined Cu/Fe molar ratio on the Al2O3 support is required for the efficient catalytic performance of the material. The study showed a beneficial effect of low iron concentration introduced into the alumina precursor during the alumina support synthesis procedure, which resulted in a homogeneous metal oxide distribution on the support.

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Correction to: Cerium–Copper–Manganese Oxides Synthesized via Solution Combustion Synthesis (SCS) for Total Oxidation of VOCs

Catalysis Letters ◽

10.1007/s10562-021-03708-3 ◽

2021 ◽

Author(s):

Miguel Jose Marin Figueredo ◽

Tahrizi Andana ◽

Samir Bensaid ◽

Melodj Dosa ◽

Debora Fino ◽

...

Keyword(s):

Combustion Synthesis ◽

Manganese Oxides ◽

Solution Combustion Synthesis ◽

Solution Combustion ◽

Total Oxidation ◽

Copper Manganese

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Comprehensive Thermal Characteristics of Different Cultivars of Flaxseed Oil (Linum usittatissimum L.)

Molecules ◽

10.3390/molecules26071958 ◽

2021 ◽

Vol 26 (7) ◽

pp. 1958

Author(s):

Jolanta Tomaszewska-Gras ◽

Mahbuba Islam ◽

Liliana Grzeca ◽

Anna Kaczmarek ◽

Emilia Fornal

Keyword(s):

Differential Scanning Calorimetry ◽

Heating Rate ◽

Fatty Acid Content ◽

Thermal Characteristics ◽

Principal Component ◽

Flaxseed Oil ◽

Scanning Calorimetry ◽

Total Oxidation ◽

Increasing Temperature ◽

Linear Correlations

The aim of this study was to describe the thermal properties of selected cultivars of flaxseed oil by the use of the differential scanning calorimetry (DSC) technique. The crystallization and melting profiles were analyzed depending on different scanning rates (1, 2, 5 °C/min) as well as oxidative induction time (OIT) isothermally at 120 °C and 140 °C, and oxidation onset temperatures (Ton) at 2 and 5 °C/min were measured. The crystallization was manifested as a single peak, differing for a cooling rate of 1 and 2 °C/min. The melting curves were more complex with differences among the cultivars for a heating rate of 1 and 2 °C/min, while for 5 °C/min, the profiles did not differ, which could be utilized in analytics for profiling in order to assess the authenticity of the flaxseed oil. Moreover, it was observed that flaxseed oil was highly susceptible to thermal oxidation, and its stability decreased with increasing temperature and decreasing heating rate. Significant negative linear correlations were found between unsaturated fatty acid content (C18:2, C18:3 n-3) and DSC parameters (OIT, Ton). Principal component analysis (PCA) also established a strong correlation between total oxidation value (TOTOX), peroxide value (PV) and all DSC parameters of thermo-oxidative stability.

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Structure, Corrosion Resistance, Mechanical and Tribological Properties of ZrB2 and Zr-B-N Coatings

Metals ◽

10.3390/met11081194 ◽

2021 ◽

Vol 11 (8) ◽

pp. 1194

Author(s):

Philipp Kiryukhantsev-Korneev ◽

Alina Sytchenko ◽

Yuriy Kaplanskii ◽

Alexander Sheveyko ◽

Stepan Vorotilo ◽

...

Keyword(s):

Corrosion Resistance ◽

Tribological Properties ◽

Current Density ◽

Corrosion Current Density ◽

Elastic Recovery ◽

Optical Emission ◽

Corrosion Current ◽

Impact Testing ◽

Total Oxidation ◽

Mechanical And Tribological Properties

The coatings ZrB2 and Zr-B-N were deposited by magnetron sputtering of ZrB2 target in Ar and Ar–15%N2 atmospheres. The structure and properties of the coatings were investigated via scanning and transmission electron microscopy, energy dispersion analysis, optical profilometry, glowing discharge optical emission spectroscopy and X-ray diffraction analysis. Mechanical and tribological properties of the coatings were investigated using nanoindentation, “pin-on-disc” tribological testing and “ball-on-plate” impact testing. Free corrosion potential and corrosion current density were measured by electrochemical testing in 1N H2SO4 and 3.5%NaCl solutions. The oxidation resistance of the coatings was investigated in the 600–800 °С temperature interval. The coatings deposited in Ar contained 4–11 nm grains of the h-ZrB2 phase along with free boron. Nitrogen-containing coatings consisted of finer crystals (1–4 nm) of h-ZrB2, separated by interlayers of amorphous a-BN. Both types of coatings featured hardness of 22–23 GPa; however, the introduction of nitrogen decreased the coating’s elastic modulus from 342 to 266 GPa and increased the elastic recovery from 62 to 72%, which enhanced the wear resistance of the coatings. N-doped coatings demonstrated a relatively low friction coefficient of 0.4 and a specific wear rate of ~1.3 × 10−6 mm3N−1m−1. Electrochemical investigations revealed that the introduction of nitrogen into the coatings resulted in the decrease of corrosion current density in 3.5% NaCl and 1N H2SO4 solution up to 3.5 and 5 times, correspondingly. The superior corrosion resistance of Zr-В-N coatings was related to the finer grains size and increased volume of the BN phase. The samples ZrB2 and Zr-B-N resisted oxidation at 600 °C. N-free coatings resisted oxidation (up to 800 °С) and the diffusion of metallic elements from the substrate better. In contrast, Zr-B-N coatings experienced total oxidation and formed loose oxide layers, which could be easily removed from the substrate.

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Association of Metabolically Healthy and Unhealthy Obesity Phenotypes with Oxidative Stress Parameters and Telomere Length in Healthy Young Adult Men. Analysis of the MAGNETIC Study

Antioxidants ◽

10.3390/antiox10010093 ◽

2021 ◽

Vol 10 (1) ◽

pp. 93

Author(s):

Mateusz Lejawa ◽

Kamila Osadnik ◽

Tadeusz Osadnik ◽

Natalia Pawlas

Keyword(s):

Oxidative Stress ◽

Telomere Length ◽

Quantitative Polymerase Chain Reaction ◽

Oxidative Stress Markers ◽

Metabolic Disturbances ◽

Total Oxidation ◽

Stress Markers ◽

Metabolic Dysregulation ◽

Total Antioxidant ◽

Metabolically Healthy

Obesity is a significant factor related to metabolic disturbances that can lead to metabolic syndrome (MetS). Metabolic dysregulation causes oxidative stress, which affects telomere structure. The current study aimed to evaluate the relationships between telomere length, oxidative stress and the metabolically healthy and unhealthy phenotypes in healthy young men. Ninety-eight participants were included in the study (49 healthy slim and 49 obese patients). Study participants were divided into three subgroups according to body mass index and metabolic health. Selected oxidative stress markers were measured in serum. Relative telomere length (rTL) was measured using quantitative polymerase chain reaction. The analysis showed associations between laboratory markers, oxidative stress markers and rTL in metabolically healthy and unhealthy participants. Total oxidation status (TOS), total antioxidant capacity (TAC) and rTL were significantly connected with metabolically unhealthy obesity. TAC was associated with metabolically healthy obesity. Telomeres shorten in patients with metabolic dysregulation related to oxidative stress and obesity linked to MetS. Further studies among young metabolically healthy and unhealthy individuals are needed to determine the pathways related to metabolic disturbances that cause oxidative stress that leads to MetS.

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