Oxidation Of Cr Research Articles

Role of Te-RE alloying on the passive film and pitting corrosion behavior of 316L stainless steel

This work reports the mechanism of corrosion resistance enhancement of 316 L stainless steel after Te-RE alloying. The individual MnS inclusions are replaced by composite inclusions, resulting in a reduced risk of pitting corrosion. The decrease of inclusion amount and Volta potential difference between inclusion and matrix induced by the addition of Te/La promoted the stability of the inclusions and lessened the active sites for pitting corrosion. TeO2 formed in the passive film with Te treatment could be easily reduced by Cr and Mo, and resulting in a significant increasing of MoO2 and Cr2O3 content in the passive film. This enhanced the stability of the passive film. Te and RE exhibited a synergistic effect on the increase of Cr and Mo in the passive film, resulting in a further improvement of the passive film. However, RE could not exist in the passive film stably due to its poor thermodynamic stability of the rare earth oxides, and only acted as a bridge for the formation of Cr and Mo oxides.

Quantitative analysis of microstructural evolution in cold-sprayed CuCrZr: Understanding heat transfer mechanisms from room temperature to 600°C

Cold-sprayed CuCrZr coating offers interesting multifunctional properties with a combination of high mechanical property, good thermal stability and substantial deposition thickness. Despite these advantages, the incorporation of solid solution elements and the deposit’s unique microstructure often result in suboptimal heat transfer capabilities. This study delved into the thermal conductivity of cold-sprayed CuCrZr coatings over a temperature range from room temperature to 600 °C. Furthermore, it quantitatively analyzed their microstructural evolution post-thermal testing and its correlation with thermal properties, employing techniques such as FESEM, EBSD, TEM, and XRD. Findings indicate the CuCrZr coating exhibits significant thermal sensitivity, with conductivity increasing from 65.83±1.79W/(m∙K) at 25 °C to 198.42±0.63W/(m∙K) at 600 °C. The annealing effect during thermal testing significantly enhances the coatings’ room temperature thermal properties, chiefly through the enhancement of interparticle metallurgical bonding, grain enlargement, solid solution precipitation, and a reduction in dislocation density. The thermal conduction across the coating/substrate interface is intricately influenced by the interplay between electrons and phonons, with impediments at the interface becoming markedly pronounced beyond 300 °C. The investigation pinpointed interparticle interfaces as the predominant barriers to heat transfer, contributing to 73.77% of the total resistance. Meanwhile, the effects of solid solution elements, grain boundaries, and dislocations on thermal conductivity were comparatively minor, contributing 9.36%, 1.04%, and 0.44%, respectively. However, it is also noted that the annealing effect can induce the coalescence of microcracks into pores and promote the precipitation or oxidation of Cr at the interfaces, which, in turn, limits the potential for further enhancements in thermal conductivity.

Creep Fatigue Interaction at high temperature in C630R ferritic/martensitic heat-resistant steel

The study investigated the creep-fatigue interaction behavior, fracture mechanism, and microstructure evolution of C630R ferritic/martensitic heat-resistant steel at 630 °C and 1% strain amplitude. The results indicate that C630R ferritic/martensitic heat-resistant steel exhibits noticeable cyclic softening behavior, with a decrease in the softening ratio from 0.46 to 0.40 as loading time increases. Microstructure evolution was examined using optical and scanning electron microscopes, revealing the appearance of secondary cracks on the longitudinal section of the sample. These cracks exhibited a curved expansion trend with multiple deformations and highly bifurcated micro-cracks at a low loading time of 30s. However, when the load holding time was increased to 300s, the fatigue cracks tended to expand in a straight line with fewer branches. Furthermore, the observed crack growth path under different loading times showed enrichment in Fe and Cr, with the crack tip containing Cr oxide, which helped prevent fatigue crack propagation. As the loading time increases, the rise in crack closure resulting from oxidation leads to a decrease in crack propagation. Electron backscatter diffraction observation revealed the formation of numerous substructures and recrystallized grains after varying holding times, enhancing the material's resistance to crack propagation. Moreover, the study found that with increasing load dwell time, the deformed grains decreased, and substructural grains became dominant (57.68% and 62.77% under 30s and 300s, respectively). This increased crack resistance resulted in shorter secondary cracks under prolonged load retention, with the secondary crack length decreasing from 146.36μm at 30s loading time to 109.09μm at 300s loading time. Additionally, the kernel misorientation angle value decreased significantly after different loading times, leading to a higher likelihood of cracks or holes forming in regions with high KAM values, where low-angle grain boundaries were formed.

Corrosion behavior and mechanism of 921 A high-strength low-alloy steel in harsh marine atmospheric environments

High-strength low-alloy 921 A steel faces significant corrosion challenges in harsh marine atmospheric conditions, threatening marine and energy industry safety. This study investigates the corrosion behavior of 921 A steel through accelerated tests in a specially developed multi-factor coupled corrosion chamber. Combining the multi-factor coupling cyclic corrosion test method with finite element numerical simulation, the long-term corrosion behavior can be accurately predicted, and the power function relationship between the corrosion rate and time of the test steel is obtained, which is expressed as C=0.2259 t–0.5182. Analysis identified α-FeOOH, Fe3O4, γ-FeOOH, Cl—, and Cr in corrosion layers. First-principles calculations and XPS analysis showed Cr oxidation inhibits Cl— adsorption and diffusion, highlighting the steel’s corrosion resistance. Finite element analysis and outdoor corrosion data confirmed the corrosion rate and time correlation, proving simulation reliability. This research provides crucial insights into 921 A steel’s corrosion resistance in marine environments, benefiting marine engineering.

Photoinduced oxidation of chromium picolinate to hexavalent chromium in the presence of ferric ions

The occurrence of chromium picolinate (Cr(pic)3) in environment has attracted raising concerns on its fate and the associated risks. Herein, the photoinduced oxidation of Cr(pic)3 in the presence of ferric ions (Fe(III)) under simulated sunlight and natural solar light irradiation were investigated. Cr(pic)3 was stable under dark or without Fe(III). 87.9 % of Cr(pic)3 (C0 = 1.0 μM) was degraded in the presence of 50 μM Fe(III) after 90 min simulated sunlight irradiation at initial pH of 4.0. •OH was the main cause for Cr(pic)3 oxidation, it attacked the chromium center to generate hexavalent chromium (Cr(VI)) and picolinic acid (k = 5.9 ×108 M−1·s−1). Picolinic acid could be further oxidized to NH4+ and small organics. Relative higher Fe(III) content (25 – 75 μM) and Cr(pic)3 concentration (0.5 – 2.0 μM) promoted both of Cr(pic)3 degradation and Cr(VI) accumulation. While, the degradation of Cr(pic)3 decreased with pH at the range of 3.0 – 8.0, more Cr(VI) was accumulated at pH 5.0 and 6.0. The co-existence of inorganic ions and dissolved organic matter (DOM) in river water inhibited Cr(pic)3 oxidation by scavenging the •OH formed and shielding the light. 8.0 – 16.7 μg/L of Cr(VI) was accumulated after 9.0 h simulated sunlight irradiation of Cr(pic)3 in river water matrix ([Fe(III)]0 = 50 – 100 μM). The generation of Cr(VI) under solar light was slower than that under simulated sunlight due to the weaker light intensity (43.2 – 85.0 mW/cm2 vs. 750 – 1300 mW/cm2). These results consistently suggest photoinduced oxidation of Cr(pic)3 in environment generates the toxic Cr(VI), which deserves significant attention.

Formation of heterogeneous microstructure and its effect on corrosion properties of high-silicon stainless steel S38815 weldment

This study aims to clarify the formation of heterogeneous microstructure and its effect on corrosion properties of high-silicon stainless steel (high-Si SS) S38815 weldment. A series of tests about microstructure and electrochemical characteristics were performed, including the electron backscatter diffraction (EBSD) analysis, Mott-Schottky tests, electrochemical impedance spectroscopy (EIS) tests, potentiodynamic and potentiostatic polarization tests. The formation mechanism of heterogeneous microstructure related to high-silicon and its correlation on corrosion was discussed extensively. The results show that the significantly deformed and recrystallised grains were observed at the low temperature heat affected zone (LT-HAZ) and high temperature heat affected zone (HT-HAZ) respectively. The metastable pitting and low impedance values were formed in the above region, despite their low donor density. The deterioration in corrosion resistance of S38815 weldment as a result of high-angle grain boundaries (HAGBs) and carbides is more pronounced than the beneficial impact of Cr and Si oxidation. This study provides valuable references to the manufacturing and enhancing the anti-corrosion properties of this high-Si SS.

Morphological Evolution and Dealloying During Corrosion of Ni20Cr (wt.%) in Molten FLiNaK Salts

The dealloying corrosion behavior of the FCC Ni20Cr (wt%) in molten LiF-NaF-KF (FLiNaK) salts at 600 °C under varying applied potentials was investigated. Using in-operando electrochemical techniques and a multi-modal suite of characterization methods, we connect electrochemical potential, thermodynamic stability, and electro-dissolution kinetics to the corrosion morphologies. Notably, under certain potential regimes, a micron-scale bicontinuous structure, characterized by a network of interconnected pores and ligaments riched with the composition of the more noble (MN) element, becomes prominent. At other potentials both MN and less noble (LN) elements dealloy but at different rates. The dealloying process consists of lattice and grain boundary diffusion of Cr to the metal/salt interface, interphase Cr oxidation, accompanied by surface diffusion of Ni to form interconnected ligaments. At higher potentials, the bicontinuous porous structure undergoes further surface coarsening. Concurrently, Cr(II), Cr(III), and Ni(II) begin to dissolve, with the dissolution of Ni occurring at a significantly slower rate. When solid-state transport of Cr is exceeded by the interfacial rates, dealloying depths are limited.

Passivation Behavior of Chromium Alloyed High-Strength Rebar in Simulated Concrete Pore Solution

In this study, SEM, AFM, TEM, XPS, and electrochemical tests are used to study the passivation behavior of chromium alloyed high-strength rebar in simulated concrete pore (SCP) solutions with different pH values. The results show that after passivation in SCP solution with different pH values, the passivating film on the surface of the chromium alloyed rebar primarily consists of a layer of nanoscale oxide particles, which makes the passive film exhibit a p-n type semi-conductor, and the passive film presents a rhombohedral crystal structure. As the pH value of the SCP solution decreases, the nanoscale oxide particles on the surface of the rebar become denser, which leads to a reduction in the carrier density (Nq and Na) of the passive film and an increase in film resistance (R2) and charge transfer resistance (R3), thus increasing the corrosion resistance of the passive film. The passive film on the surface of the chromium alloyed high-strength rebar predominantly exhibits a three-layer structure, the outer passive film layer is composed of Fe oxides, the stable layer of the passive film is composed of Fe oxides and Cr oxides, and the growth layer of inner passive film is composed of Cr oxides. Compared with passivation 10 d in SCP solutions with pH 13.5 and pH 12.5, the passive film on the surface of the rebar has good stability at pH 10.5, which indicates that the addition of Cr is beneficial to promote the corrosion resistance of the rebar.

Effect of Annealing after Casting and Cold Rolling on Microstructure and Electrochemical Behavior of High-Entropy Alloy, Cantor

High-entropy alloys (HEAs), a relatively new class of materials, have attracted significant attention in materials science owing to their unique properties and potential applications. High entropy stabilizes the phase of a solid solution over a wide range of chemical compositions, yielding unique properties superior to those of conventional alloys. Therefore, this study analyzed the microstructure and electrochemical behavior of HEAs (Cantor) to evaluate their corrosion resistance, according to their manufacturing process (casting, cold rolling, and annealing). The microstructural morphologies and sizes were analyzed using electron backscatter diffraction. The electrochemical behavior was examined using open circuit potential measurements, electrochemical impedance spectroscopy, potentiodynamic polarization tests, and critical pitting temperature measurements using a potentiostat. The casting process formed a nonuniform microstructure (average grain size = 19 μm). The cold rolling process caused the formation of fine grains (size = 4 μm). A uniform microstructure (grain size > 151 μm) was formed after heat treatment. The corrosion resistance of the HEAs was determined from the passivation layer formed by Cr oxidation. These microstructural differences resulted in variations in the electrochemical behavior. Microstructural and electrochemical analyses are crucial because HEAs have diverse potential applications. Therefore, this study contributes to future improvements in HEA manufacturing processes.

Electrochemical Characterization of Passive Film and Corrosion in Co-rich High Entropy Alloys in Ringer’s Solution

This study investigates the corrosion characteristics of Co30Cr20Ni20Fe20Mo10 (Co30HEA), Co40Cr20Ni15Fe15Mo10 (Co40HEA), and Co50Cr20Ni10Fe10Mo10 (Co50HEA), designed as Co-rich high entropy alloys, compared to 316L stainless steel and L605. Co30HEA has a single FCC phase, whereas the other two alloys exhibit a dual phase of FCC + (Cr, Mo) σ phase. The presence of high Cr and Mo content in the σ phase results in Cr depletion zones. Co30HEA shows the highest corrosion resistance in Ringer's solution, which diminishes with increasing Co content. Its passive film exhibits ideal capacitive behavior at low frequencies, indicating strong passivation. The films, primarily composed of Cr oxides and hydroxides, vary in thickness, with Co30HEA having a film about twice as thick as the others. All three alloys demonstrate pitting corrosion; however, Co30HEA shows the smallest pits mainly at grain boundaries, while the others show pits near the σ phase due to unstable passive films in the Cr and Mo-depleted zones, acting as anodic sites for galvanic corrosion.

Mechanical and Corrosion Properties of Super Austenitic Stainless Steel Joint for Double‐Sided Synchronous TIP TIG Arc Butt Welding

Super austenitic stainless steel 254SMO (254SMO SASS) plates are joined by double‐sided double‐arc synchronous TIP TIG butt welding (DSSTTABW) using ER NiCrMo3 wire, and the micro‐structure, mechanical and corrosion properties of 254SMO SASS joints are investigated subsequently. Results show that solidification grain boundary and solidification sub‐grain boundary can be observed in fusion zone. A small amount of σ phase precipitates in the weld, while χ phase is found in the transition zone, but no solidification crack occurs in weld and heat affected zone (HAZ). 254SMO SASS joint has higher micro‐hardness and lower tensile strength and elongation compared to base metal. During transverse tensile process, 254SMO SASS joints fail in the weld zone in a ductile mode. Electrochemical corrosion performance tests indicate that 254SMO SASS joint achieve equivalent pitting corrosion resistance and similar passive mechanism to base metal in 3.5 wt% NaCl solution. The passivation film on the surface of both joint and base metal display as n‐p semi‐conductive character, but the film stability of 254SMO joint surface is slightly poorer compared to base material. The surface passivation film of 254SMO joint primarily consists of oxides of Fe, Cr, and Mo before potentiodynamic polarization, while hydroxides of Fe and Cr are also observed after polarization.

High-Temperature Oxidation and Phase Stability of AlCrCoFeNi High Entropy Alloy: Insights from In Situ HT-XRD and Thermodynamic Calculations.

The high-temperature oxidation behaviour and phase stability of equi-atomic high entropy AlCrCoFeNi alloy (HEA) were studied using in situ high-temperature X-ray diffraction (HTXRD) combined with ThermoCalc thermodynamic calculation. HTXRD analyses reveal the formation of B2, BCC, Sigma and FCC, phases at different temperatures, with significant phase transitions observed at intermediate temperatures from 600 °C-100 °C. ThermoCalc predicted phase diagram closely matched with in situ HTXRD findings highlighting minor differences in phase transformation temperature. ThermoCalc predictions of oxides provide insights into the formation of stable oxide phases, predominantly spinel-type oxides, at high p(O2), while a lower volume of halite was predicted, and minor increase observed with increasing temperature. The oxidation behaviour was strongly dependent on the environment, with the vacuum condition favouring the formation of a thin, Al2O3 protective layer, while in atmospheric conditions a thick, double-layered oxide scale of Al2O3 and Cr2O3 formed. The formation of oxide scale was determined by selective oxidation of Al and Cr, as further confirmed by EDX analysis. The formation of thick oxide in air environment resulted in a thick layer of Al-depleted FFC phase. This comprehensive study explains the high-temperature phase stability and time-temperature-dependent oxidation mechanisms of AlCrCoFeNi HEA. The interplay between surface phase transformation beneath oxide scale and oxides is also detailed herein, contributing to further development and optimisation of HEA for high temperature applications.

Effect of Temperature on Passive Film Characteristics of LPBF (Laser Powder-Bed Fusion) Processing on UNS-S31603.

The effect of temperature on the localized corrosion resistance and passive film characteristics of laser powder-bed fusion (LPBF) 316L (UNS S31603) was studied in a buffered 3.5 wt% NaCl solution at 25, 50, and 75 °C. DC techniques such as cyclic potentiodynamic polarization showed lower passive current densities, high breakdown potentials, and a higher resistance to initial breakdown compared with wrought 316L samples at all temperatures. However, LPBF 316L was more susceptible to metastable pitting at potentials before film breakdown and higher damage accumulation post film breakdown. AC techniques, such as Mott-Schottky analysis and electrochemical impedance spectroscopy, showed that the formed passive film was more robust on the LPBF 316L samples at all temperatures, accounting for the higher initial resistance to pitting. However, with increasing temperatures, the film formed had an increasing concentration of defect density. Passive compositions at the various test temperatures studied using X-ray photoelectron spectroscopy (XPS) showed that the LPBF samples showed higher amounts of Cr and Fe oxides and hydroxides compared with the wrought samples, which made the passive films on the LPBF samples more compact and protective. Investigation of the pits formed on the LPBF showed the preferential regions of attack were the melt-pool boundaries and cell interiors due to their being depleted of Cr and Mo when compared with the boundaries and matrix.

Design of corrosion-resistant alloys for preventing oxidation-induced nanoscale Cr-depletion by inclusion engineering

Due to the preferential oxidation of Cr in various corrosion-resistant alloys, Cr-depletion extensively forms around the oxides and impairs passivation ability. This harmful effect has been widely recognized, but available solutions are limited. Here, to prevent such oxidation-induced Cr-depletion in corrosion-resistant alloys, we proposed a general strategy based on inclusion engineering using oxygen-preferred elements in alloy design. The inclusion-Cr depletion-passivation relationship was systematically studied in 3.5 wt% NaCl using commercially cast original, Si-modified, Al-modified, and Ti-modified CoCrFeMnNi alloys, in which the prominent inclusions were identified as MnCr2O4, MnO-SiO2, AlN, and TiN, respectively. Unlike the original alloy, all modified alloys prevented Cr-depletion with improved corrosion resistance; however, the Si-modified alloy exhibited the most remarkable improvement due to few nitride by-products. Thermodynamic analysis on the free energy changes of potential reactions revealed that all the additives were preferential to be oxidized over Cr, whereas Al and Ti nitridation reactions have the most negative free energies compared to all oxidation reactions, which validated experimental results. From experiments and thermodynamics, an effective method was proposed, and its application was discussed with three newly-designed alloys prepared using arc melting. We believe the proposed strategy can be widely used in designing alloys to prevent oxidation-induced Cr-depletion.

Microstructure evolution during oxidation of protruded NiCoCrAlYTa-Al2O3 abrasive coating produced by vacuum infiltration sintering

In this paper, protruded NiCoCrAlYTa-Al2O3 abrasive coatings were prepared by vacuum infiltration sintering, and the effect of the filler metal content on the microstructure before and after oxidation is investigated. The results show that, the Al2O3 grits are bonded to the coating matrix by a layer of Y-Al-O compound, and various types of G-phase are presented depending on the locations. Adjacent to the G-phase, larger γ' phase and γ/γ' eutectics are presented due to the expel of Al during the formation of G-phase. With the increase of the filler metal content, G-phase precipitation and the Si penetration depth into the single crystal superalloy substrate increase. After 1000 °C/100 h oxidation, the Y-Al-O intermediate layer between Al2O3 grits and the coating matrix is little changed, with an additional thermally grown oxide (TGO) layer between the Y-Al-O layer and the coating matrix presented. The selective oxidation of Al and Cr facilitates the formation of G-phase layer underneath the oxide film, and the rapid diffusion of Ti and the selective oxidation of Al yields the formation of γ' depletion region adjacent to the G-phase and on coating surface without Al2O3 grits.

Tribochemistry dependence of Ni62Nb33Zr5 bulk metallic glass on the Cr content of steel counterparts

Recent literature showed that Bulk Metallic Glasses can demonstrate repeatable tribological response, and that it might be controlled through a careful selection of the sliding counterpart’s composition. The present study focuses on the effect of Cr content of a steel ball sliding over a Ni62Nb33Zr5 BMG. Three different steels were chosen (C90, 100Cr6, and X105CrMo17) because they demonstrate similar constitutive elements, similar mechanical properties, but different Cr contents. Increasing Cr content resulted in an increase of friction coefficient from 0.13 to 0.85 while maintaining extremely low wear. In depth chemical analysis showed that increasing Cr content favors the loss of the ductile Nb2O5 of protective FeNbO4, and NiNb-oxide to the benefit of NiCrO, CrNbO4, NiFe-oxides, and Cr(VI) oxide.

Effect of Nb addition on the steam oxidation behavior and kinetic of FeCrAl alloys

The effects of Nb on the steam oxidation kinetic behavior of FeCrAl alloy were studied. Nb addition significantly decreased the weight gain at 1200 °C. Nb addition also promoted the formation of Al2O3 and suppressed the growth of Fe and Cr oxides, resulting in the thinner oxide film in the heating stage. Also, the oxide film is much easier to wrinkle at 1200 °C. In addition, pre-formed Nb2O5 promotes the formation of discontinuous granular Al2O3 in oxide films and substrates.

Enhanced photocatalytic degradation of Congo red dye into safe end-products over ZnO@polyaniline/coal composite as low cost catalyst under visible light: Pathways and ecotoxicity

ZnO@polyaniline/coal nanocomposite (ZnO@PANI/C) was synthesized and characterized by different analytical techniques as potential enhanced photocatalyst for the successful oxidation of Congo red dye (CR) into eco-friendly end-products. The investigated CR concentration (5 mg/L) was completely decolorized after 120 min, 100 min, 80 min, and 40 min after the incorporation of ZnO@PANI/C dosages at 0.2 g/L, 0.3 g/L, 0.4 g/L, and 0.5 g/L, respectively. The synergetic studies demonstrate a significant impact of the integrated components (coal, polyaniline (14.2 % oxidation of CR), ZnO (21.6 % oxidation of CR), 43.7 % (PANI/C oxidation of CR), and 64.3 % (ZnO/C oxidation of CR)) on the catalytic activity of ZnO@PANI/C (100 % oxidation of CR), which is higher than that of the individual components. The investigation of TOC content reflects that the complete mineralization can be detected after 100 min and validates the formation of different species of intermediates started by sodium-3-(phenyl diazenyl) naphthalene-1-sulfonate until detecting ethyl benzene. The findings of the oxidizing trapping tests demonstrate the controlling impact of the hydroxyl radicals as the oxidation in the presence of its trapping reagent (Isopropanol) declined to 8.6 %. The oxidation pathway of CR over ZnO@PANI/C involved a progressive series of decarboxylation and dihydroxylation ended by ethylbenzene, which in turn produced nontoxic products such as H2O and CO2. The eco-toxicity tests reflect the efficiency of the photo-oxidation of CR contaminants by ZnO@PANI/C in reducing acute toxicity (LC50 and EC50 > 100) and chronic (ChV > 10) toxicities of CR dye after 60 min of remediation.

Investigating the Effects of CoMoCrSi Powder Composition and Particle Size, and Annealing Heat Treatment on Microstructure and Mechanical and Tribological Performance of HVOF Sprayed Coatings

AbstractAn investigation was conducted to analyze the mechanical properties, wear behavior, and microstructure of coatings formed by high-velocity oxygen fuel spraying of CoMoCrSi powders. The effects of varying Cr concentration and particle sizes before and after heat treatment at 900 °C for 4 h were studied comparatively. The increase in Cr and Mo elements in the expanse of Co increased the structure's hardness before and after the heat treatment. As this increase was 10% in as-sprayed conditions, annealing raised the increase to 30%. Splat boundaries were the most vulnerable constituents against forces, creating a significant disadvantage in terms of structural integrity and affecting the overall performance. After annealing, the boundary strengths experienced a remarkable four-fold increase and cracks and fractures reduced significantly. The susceptibility of splat boundaries had a detrimental effect on room temperature wear behavior, and increased boundary densities led to a marked reduction in wear performance. Heat treatment induced improvements significantly increased the room temperature wear performance. At elevated temperature, the formation of oxide layers composed of CoMoO4, Co3O4, MoO3, and Cr2O3 overcame the weaknesses of the as-sprayed coating, reducing both the friction coefficient and wear losses. A reduced Co ratio led to the formation of an oxide blend with a higher concentration of Mo and Cr oxides on the surface, further improving the coating's wear behavior. Graphical Abstract

Analysis of mercury removal and sulfur resistance of CrOx-MnOx-SnOx-TiO2 catalysts

To investigate the ability of CrOx-MnOx-SnOx-TiO2 composite catalysts to adsorb and remove substances, particularly in the presence or absence of SO2, Sn was included in CrMnTi catalysts throughout the production procedure. The incorporation of Sn was found to boost the specific surface area, optimize the pore structure, and augment the number of active sites, as determined using characterization methods such as XRD, XPS, and BET. When Sn metal oxides were included in MnTi catalysts individually, the resulting MnSnTi catalysts showed a limited capacity to remove Hg0. However, adding Sn metal oxides allowed for widening the temperature range in which the catalysts found successful application. This will increase the range of application temperature and is of very successful importance for large-scale commercial applications. They demonstrate that, by incorporating chromium metal oxides, the oxygen Oβ reactivity within the MnSnTi catalyst increases, resulting in a greatly improved capacity for Hg0 removal and its resistance to sulfur. This study details the combined effect of Cr, Mn, and Sn ternary composite oxides on sulfur resistance and mercury removal. The result shows that Sn promotes the strengthening of both the physical properties of the catalyst and the adsorption of mercury while also assisting in the dispersion of the catalyst. Cr enhances the ability of the catalyst to transfer electrons while in oxidation and, at the same time, favours the remaining high valence of Mn. Mn supports the catalyst for oxidizing mercury by changing its multivalent state. The CrMnSnTi catalysts have exceptional efficacy in removing mercury and possess excellent resistance to sulfur, making them an ideal catalytic option for industrial demercury removal. The catalysts exhibited excellent efficacy in removing mercury and showed strong sulfur resistance.