Model Catalysts Research Articles

Elucidating the Geometric Active Sites for Oxygen Evolution Reaction on Crystalline Iron-Substituted Cobalt Hydroxide Nanoplates.

Transition-metal (oxy)hydroxides are among the most active and studied catalysts for the oxygen evolution reaction in alkaline electrolytes. However, the geometric distribution of active sites is still elusive. Here, using the well-defined crystalline iron-substituted cobalt hydroxide as a model catalyst, we reported the scanning electrochemical cell microscopy (SECCM) study of single-crystalline nanoplates, where the oxygen evolution reaction at individual nanoplates was isolated and evaluated independently. With integrated prior- and post-SECCM scanning electron microscopy of the catalyst morphology, correlated structure-activity information of individual electrocatalysts was obtained. Our result reveals that while the active sites are largely located at the edges of the pristine Co(OH)2 nanoplates, the Fe lattice incorporation significantly promotes the basal plane activities. Our approach of correlative imaging provides new insights into the effect of iron incorporation on active site distribution across nano-electrocatalysts.

Crystal facet effect of γ-Al2O3 on catalytic property of CuO/γ-Al2O3 for CO oxidation

CuO/γ-Al2O3 is an important model catalyst and has received research attentions for a long-time. In this work, a special catalyst of CuO/γ-Al2O3 prepared using γ-Al2O3 nanotubes mainly exposing {111} planes as support, synthesized by a special method, was employed for CO oxidation and the impact of Its exposed facets on the properties of CuO/γ-Al2O3 catalyst was elaborately investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), electron spin resonance (ESR), temperature programmed reduction (TPR), and in situ infrared absorption spectroscopy of CO experiments (CO-IR). The results showed that the CuO species supported on {111} facet-exposed γ-Al2O3 nanotube had better dispersity and stronger interaction as comparing to the {110} facet-exposed γ-Al2O3 nanosheet, which could be reduced to Cu+ at lower temperature of 150 °C and thus formed into adsorbed COCu+ which was the necessary prerequisite for CO oxidation, and the activity test validated the CO were totally oxidized over the CuO/γ-Al2O3 with {111} plane below 230 °C. The improved catalytic activity of CuO/γ-Al2O3 by manipulating the exposed facets of crystal carrier offers a deep insight into the catalytic mechanism of loaded CuO species and points out the direction for the design of other catalyst systems.

CO self-sustained catalytic combustion over morphological inverse model CeO2/Cu2O catalysts exposing (1 0 0), (1 1 1) and (1 1 0) planes

CO self-sustaining catalytic combustion tends to be one of potential means to achieve efficient conversion of off-gases from steelmaking. Building model catalysts to investigate the reaction process academically is essential to design optimized catalysts and Cu2O exposing (1 0 0), (1 1 1) and (1 1 0) planes are excellent materials. Herein, morphological CeO2/Cu2O inverse model catalysts were synthesized to reveal the synergistic effect and reaction mechanism. It is demonstrated that the ignition temperature is lowered on the interface by synergistic effect, which dominates the ignition, while the combustion after ignition is controlled by Cu2O planes providing abundant lattice oxygen to react with CO. Additionally, exposure of different planes plays a significant role in the reaction since O-termination on (1 0 0) inhibits the interaction, whereas Cu-termination on (1 1 0) surface structure and coordinately unsaturated Cu+ on open (1 1 1) surface respectively contribute to their superior catalytic performance.

CO2 methanation over Ni nanoparticles inversely loaded with CeO2 and Cr2O3: Catalytic functions of metal oxide/Ni interfaces

Interfaces between active metal and metal oxide in a heterogenous catalyst often play an important role in catalysis. In this work, we intentionally synthesized a series of inverse CeO2-Cr2O3/Ni model catalysts with the formation of controlled CeO2-Ni and Cr2O3-Ni interfacial structures and investigated the roles of the oxide-metal interfaces in CO2 methanation performance through excluding the normal support effect. Experimental and DFT calculation results reveal that the formate pathway tends to occur on the catalyst with only CeO2-Ni interfaces. The Cr2O3-Ni interface formed after introducing Cr oxide alters the nearby CeO2-Ni interface by electron transfer through Ni, which brings an additional reaction pathway (CO pathway) on CeO2-Cr2O3/Ni. Furthermore, it shows a relatively lower CO2 absorption energy and activation energy barrier for CO2 dissociation to CO at the Cr2O3-Ni interface, favorable for CO2 activation and further hydrogenation, thus leading to excellent low-temperature activity.

Calix[4]arene-Functionalized Titanium-Oxo Compounds for Perceiving Differences in Catalytic Reactivity Between Mono- and Multimetallic Sites.

While the difference in catalytic reactivity between mono- and multimetallic sites is often attributed to more than just the number of active sites, still few catalyst model systems have been developed to explore more underlying causal factors. In this work, we have elaborately designed and constructed three stable calix[4]arene (C4A)-functionalized titanium-oxo compounds, Ti-C4A, Ti4-C4A, and Ti16-C4A, with well-defined crystal structures, increasing nuclearity, and tunable light absorption capacity and energy levels. Among them, Ti-C4A and Ti16-C4A can be taken as model catalysts to compare the differences in reactivity between mono- and multimetallic sites. Taking CO2 photoreduction as the basic catalytic reaction, both compounds can achieve CO2-to-HCOO- conversion with high selectivity (close to 100%). Moreover, the catalytic activity of multimetallic Ti16-C4A is up to 2265.5 μmol g-1 h-1, which is at least 12 times higher than that of monometallic Ti-C4A (180.0 μmol g-1 h-1), and is the best-performing crystalline cluster-based photocatalyst known to date. Catalytic characterization combined with density functional theory calculations shows that in addition to the advantage of having more metal active sites (for adsorption and activation of more CO2 molecules), Ti16-C4A can effectively reduce the activation energy required for the CO2 reduction reaction by completing the multiple electron-proton transfer process rapidly with synergistic metal-ligand catalysis, thus exhibiting superior catalytic performance to that of monometallic Ti-C4A. This work provides a crystalline catalyst model system to explore the potential factors underlying the difference in catalytic reactivity between mono- and multimetallic sites.

Unraveling the Electronic Structure and Dynamics of the Atomically Dispersed Iron Sites in Electrochemical CO2 Reduction.

Single-atom catalysts with a well-defined metal center open unique opportunities for exploring the catalytically active site and reaction mechanism of chemical reactions. However, understanding of the electronic and structural dynamics of single-atom catalytic centers under reaction conditions is still limited due to the challenge of combining operando techniques that are sensitive to such sites and model single-atom systems. Herein, supported by state-of-the-art operando techniques, we provide an in-depth study of the dynamic structural and electronic evolution during the electrochemical CO2 reduction reaction (CO2RR) of a model catalyst comprising iron only as a high-spin (HS) Fe(III)N4 center in its resting state. Operando 57Fe Mössbauer and X-ray absorption spectroscopies clearly evidence the change from a HS Fe(III)N4 to a HS Fe(II)N4 center with decreasing potential, CO2- or Ar-saturation of the electrolyte, leading to different adsorbates and stability of the HS Fe(II)N4 center. With operando Raman spectroscopy and cyclic voltammetry, we identify that the phthalocyanine (Pc) ligand coordinating the iron cation center undergoes a redox process from Fe(II)Pc to Fe(II)Pc-. Altogether, the HS Fe(II)Pc- species is identified as the catalytic intermediate for CO2RR. Furthermore, theoretical calculations reveal that the electroreduction of the Pc ligand modifies the d-band center of the in situ generated HS Fe(II)Pc- species, resulting in an optimal binding strength to CO2 and thus boosting the catalytic performance of CO2RR. This work provides both experimental and theoretical evidence toward the electronic structural and dynamics of reactive sites in single-Fe-atom materials and shall guide the design of novel efficient catalysts for CO2RR.

Recent Mechanistic Understanding of Fischer-Tropsch Synthesis on Fe-Carbide

With an increase in energy consumption globally, Fischer-Tropsch (FT) synthesis is a good alternative for producing fuels and chemicals from coal, natural gas or biomass. Among them, coal to liquids has been put into production in countries that have large coal reserves. In this process, Fe-based catalysts are commonly used due to their earth abundance, comparatively wide operation range and ready availability to handle low H2/CO ratio from coal. Despite their extensive applications, the kinetic and mechanistic understandings of Fe carburization and FT reaction on Fe-carbides are relatively limited due to the complexity of the phase composition of the applied catalysts. This review summarizes the current state of knowledge of FT synthesis on Fe-carbide with an emphasis on the underlying mechanism. Specifically, the employment of a model catalyst, such as Raney Fe, could provide a convenient way to furnish kinetic information regarding Fe carburization and subsequent FT reaction. A major challenge for further understanding catalytic reactions occurring at the Fe-carbide surface is correlating FT activity and selectivity to a specific active site. To address this issue, the advancements of both DFT calculations and surface science techniques are highly demanded.

Electrochemical NO3- Reduction Catalyzed by Atomically Precise Ag30Pd4 Bimetallic Nanocluster: Synergistic Catalysis or Tandem Catalysis?

Electrochemically converting NO3- compounds into ammonia represents a sustainable route to remove industrial pollutants in wastewater and produce valuable chemicals. Bimetallic nanomaterials usually exhibit better catalytic performance than the monometallic counterparts, yet unveiling the reaction mechanism is extremely challenging. Herein, we report an atomically precise [Ag30Pd4 (C6H9)26](BPh4)2 (Ag30Pd4) nanocluster as a model catalyst toward the electrochemical NO3- reduction reaction (eNO3-RR) to elucidate the different role of the Ag and Pd site and unveil the comprehensive catalytic mechanism. Ag30Pd4 is the homoleptic alkynyl-protected superatom with 2 free electrons, and it has a Ag30Pd4 metal core where 4 Pd atoms are located at the subcenter of the metal core. Furthermore, Ag30Pd4 exhibits excellent performance toward eNO3-RR and robust stability for prolonged operation, and it can achieve the highest Faradaic efficiency of NH3 over 90%. In situ Fourier-transform infrared study revealed that a Ag site plays a more critical role in converting NO3- into NO2-, while the Pd site makes a major contribution to catalyze NO2- into NH3. The bimetallic nanocluster adopts a tandem catalytic mechanism rather than a synergistic catalytic effect in eNO3-RR. Such finding was further confirmed by density functional theory calculations, as they disclosed that Ag is the most preferable binding site for NO3-, which then binds a water molecule to release NO2-. Subsequently, NO2- can transfer to the vicinal exposed Pd site to promote NH3 formation.

Liquid Gallium-Assisted Patterned Growth of β-Ga2O3 Nanowires on Metallic Foils for Photocatalytic Dye Degradation

Herein, we report a facile and effective strategy for patterned growth of one-dimensional (1D) β-Ga2O3 nanowires on metallic substrates, based on the alloying of liquid gallium as a precursor. To demonstrate this method, the specific patterns are painted using gallium on a metallic foil through screen printing, which produces an intermetallic phase by alloying. The subsequent thermal treatment involving the sputtering Au serves as a catalyst to induce the formation of β-Ga2O3 nanowires on the foil. Notably, the gallium in the intermetallic phase maintains the in situ growth of nanowires. Such a growth process depends on the Au sputtering and temperature, which well follows a classical vapor–liquid–solid mechanism. Interestingly, benefiting from the unique physiochemical attributes of liquid gallium, the convenient alloying facilitates the synthesis of the nanowires at a moderately low temperature. This synthetic approach is also universal for a series of metallic substrates including Ag, Cu, Ni, and Co foils, and the production can be scaled up easily. Furthermore, as a model catalyst, the β-Ga2O3 nanowires grown on Ag foil (β-Ga2O3/Ag) display good photocatalytic performance and easy recovery in the degradation of dyes. The work provides an avenue to prepare patterned β-Ga2O3 nanowires based on liquid gallium.

Mesoporous Manganese Oxides with High-Valent Mn Species and Disordered Local Structures for Efficient Oxygen Electrocatalysis.

Active and nonprecious-metal bifunctional electrocatalysts for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are vital components of clean energy conversion devices such as regenerative fuel cells and rechargeable metal-air batteries. Porous manganese oxides (MnOx) are promising electrocatalyst candidates because of their high surface area and the abundance of Mn. MnOx catalysts exhibit various oxidation states and crystal structures, which critically affect their electrocatalytic activity. These effects remain elusive mainly because the synthesis of oxidation-state-controlled porous MnOx with similar structural properties is challenging. In this work, four different mesoporous manganese oxides (m-MnOx) were synthesized and used as model catalysts to investigate the effects of local structures and Mn valence states on the activity toward oxygen electrocatalysis. The following activity trends were observed: m-Mn2O3 > m-MnO2 > m-MnO > m-Mn3O4 for the ORR and m-MnO2 > m-Mn2O3 > m-MnO ≈ m-Mn3O4 for the OER. These activity trends suggest that high-valent Mn species (Mn(III) and Mn(IV)) with disordered atomic arrangements induced by nanostructuring significantly influence electrocatalysis. In situ X-ray absorption spectroscopy was used to analyze the changes in the oxidation states under the ORR and OER conditions, which showed the surface phase transformation and generation of active species during electrocatalysis.

Experimental study and modeling of a packed bed bioreactor for urea removal in wines

The study involved the development and modeling of a fixed-bed bioreactor for the removal of urea from wines. The reactor, based on the immobilization of acid urease enzyme, was studied under both stationary and non-stationary conditions. The developed model, including internal and external catalyst particle mass transfer, Michaelis-Menten kinetics, convection and dispersion in the liquid along the reactor axis, was able to produce urea concentration profiles in both the solid and liquid phases under various volumetric flow rates and inlet urea concentrations. The experimental results were in good agreement with the model predictions, the mean relative error between simulated and experimental outlet ammonia concentration ranging from 4.1 % to 16.4 %. Model simulations confirmed that in wines the reaction kinetics is of the pseudo-first order and that internal and external catalyst particle diffusion limitations are negligeable. Simulations of the decrease of urea concentration as a function of space velocity for the reactor under study operating in the continuous mode and for three different wines were obtained confirming that urea removal by immobilized urease in wines is more difficult than in sake. The results obtained form the basis for the designing and scaling up of bioreactors for the treatment of wines.

Active Site Tailoring of Metal‐Organic Frameworks for Highly Efficient Oxygen Evolution

AbstractThe direct correlation between active sites and catalytic activity in multiple‐component metal‐organic frameworks (MOFs) is key to understanding their mechanism of oxygen evolution reaction (OER) but remains vague. Herein, supported multiple‐site MOFs are adopted as model catalysts to quantitatively study the composition‐dependent OER performance. Ni MOFs on Fe metal substrate possess the highest intrinsic OER activity with the Ni/Fe ratio of 1:2 in the presence of metal leaching of the substrate during synthesis. Further introducing a proper amount of Cu further boosts the OER performance of Cu‐doped NiFe MOFs with an impressively low overpotential of 200 mV at 10 mA cm−2. Spectroscopic analysis with theoretical study indicates that the copper doping within the NiFe MOFs induces electron redistribution for high valence Fe sites with an optimized balance of OH/OOH adsorption and decreased energy barrier for improved OER. This work sheds light on the active site tailoring of MOFs which highly correlates with the OER activity.

Unraveling the Dynamic Structural Evolution of Phthalocyanine Catalysts during CO2 Electroreduction

Understanding the atomic and electronic changes of active sites promotes the whole new sight into electrochemical carbon dioxide reduction reaction (CO2RR), which provides a feasible strategy to achieve carbon neutrality. Here we employ operando high-energy resolution fluorescence-detected X-ray absorption spectroscopy (HERFD-XAS) to track the structural evolution of Ni(II) phthalocyanine (NiPc), considered as the model catalysts with uniform Ni-N4-C8 moiety, during the CO2RR. The HERFD-XAS method is in favor of elucidating the interaction of the reactant/catalyst interface from the atomic electronic structure dimension, facilitating the establishment of the catalytic mechanism and the dynamic structure changes. Based on operando measurement, surface sensitive difference spectra (Δµ) and spectroscopy simulation, the interfacial interactions between the active sites of NiPc and reactants are monitored and the Ni species gradually reduced by increasing the applied potential is discovered. HERFD-XAS method offers an advanced and powerful tool for elucidating the complex catalytic mechanism in further various systems.

Porous Host-Guest MOF-Semiconductor Hybrid with Multisites Heterojunctions and Modulable Electronic Band for Selective Photocatalytic CO2 Conversion and H2 Evolution.

Optimizing catalysts for competitive photocatalytic reactions demand individually tailored band structure as well as intertwined interactions of light absorption, reaction activity, mass, and charge transport. Here, a nanoparticulate host-guest structure is rationally designed that can exclusively fulfil and ideally control the aforestated uncompromising requisites for catalytic reactions. The all-inclusive model catalyst consists of porous Co3 O4 host and Znx Cd1- x S guest with controllable physicochemicalproperties enabled by self-assembled hybrid structure and continuously amenable band gap. The effective porous topology nanoassembly, both at the exterior and the interior pores of a porous metal-organic framework (MOF), maximizes spatially immobilized semiconductor nanoparticles toward high utilization of particulate heterojunctions for vital charge and reactant transfer. In conjunction, the zinc constituent band engineering is found to regulate the light/molecules absorption, band structure, and specific reaction intermediates energy to attain high photocatalytic CO2 reduction selectivity. The optimal catalyst exhibits a H2 -generation rate up to 6720µmol g-1 h-1 and a CO production rate of 19.3µmol g-1 h-1 . These findings provide insight into the design of discrete host-guest MOF-semiconductor hybrid system with readily modulated band structures and well-constructed heterojunctions for selective solar-to-chemical conversion.

Liquid Organic Hydrogen Carriers: Model Catalytic Studies on the Thermal Dehydrogenation of 1-Cyclohexylethanol on Pt(111)

The molecule pair of 1-cyclohexylethanol and acetophenone represents an interesting system for a chemical hydrogen storage cycle as it combines two different classes of so-called liquid organic hydrogen carriers (LOHCs), namely hydrogenated, formerly aromatic cyclic hydrocarbons and alcohols, i.e., hydrogenated carbonyls. In particular, the latter have recently attracted much attention due to their favorable dehydrogenation temperatures and the possibility to convert them directly into electricity in specially designed direct-LOHC fuel cells. Herein, we investigate the temperature-triggered dehydrogenation reaction of 1-cyclohexylethanol to acetophenone on a Pt(111) model catalyst using synchrotron-based temperature-programed X-ray photoelectron spectroscopy. To obtain a complete picture of the reaction mechanism, we consider not only the individual surface reactions of 1-cyclohexylethanol and acetophenone but also those of two potential dehydrogenation intermediates, namely, the partially dehydrogenated 1-cyclohexylethanone and 1-phenylethanol. We find a stepwise dehydrogenation of 1-cyclohexylethanol: the first step around ∼210 K at the alcohol moiety yields the ketone 1-cyclohexylethanone. The second step above ∼260 K at the cyclohexyl group is accompanied by the loss of an H-atom at the molecule’s methyl group and leads to the formation of an acetophenone-like phenyl–C(O)–CH2 species at ∼340 K. The same species are also identified in the surface reactions of acetophenone, 1-phenylethanol, and 1-cyclohexylethanone in this temperature range. Overall, the system shows good thermal robustness: a complete dehydrogenation of the hydrogen-rich carrier occurs without damage to the carbon framework.

Triggering Pt Active Sites in Basal Plane of Van der Waals PtTe2 Materials by Amorphization Engineering for Hydrogen Evolution.

Exposing active sites and optimizing their binding strength to reaction intermediates are two essential strategies to significantly improve the catalytic performance of 2D materials. However, pursuing an efficient way to achieve these goals simultaneously remains a considerable challenge. Here, using 2D PtTe2 van der Waals material with a well-defined crystal structure and atomically thin thickness as a model catalyst, it is observed that a moderate calcination strategy can promote the structural transformation of 2D crystal PtTe2 nanosheets (c-PtTe2 NSs) into oxygen-doped 2D amorphous PtTe2 NSs (a-PtTe2 NSs). The experimental and theoretical investigations cooperatively reveal that oxygen dopants can break the inherent Pt-Te covalent bond in c-PtTe2 NSs, thereby triggering the reconfiguration of interlayer Pt atoms and exposing them thoroughly. Meanwhile, the structural transformation can effectively tailor the electronic properties (e.g., the density of state near the Fermi level, d-band center, and conductivity) of Pt active sites via the hybridization of Pt 5d orbitals and O 2p orbitals. As a result, a-PtTe2 NSs with large amounts of exposed Pt active sites and optimized binding strength to hydrogen intermediates exhibit excellent activity and stability in hydrogen evolution reaction.

Direct Valorization of Recycled Palladium as Heterogeneous Catalysts for Total Oxidation of Methane

Electronic waste as an alternative source of palladium is used for the preparation of heterogeneous catalysts for methane oxidation. The strategy developed in this paper involves two steps: optimization of the leaching protocol to recover the Pd from the waste, and development of a suitable impregnation protocol directly from the leachate, which is a strongly acidic solution. The precipitation-deposition technique is particularly suitable for the preparation of catalysts from acidic media. The impact of Ba, Bi, and Ag impurities on the catalytic performance is studied on model catalysts. The presence of these elements and their impact on the catalytic properties are analyzed and discussed using X-ray diffraction, nitrogen physisorption, scanning and transmission electron microscopy. Through variation of the pH, the impurities co-deposited with Pd can be limited and the catalytic performance of catalysts derived from real waste can be greatly enhanced.

Band edges positions prediction of the of Ag nanocluster-decorated titania surfaces and their relationship to NO and NO2 interaction from first-principles calculations

Metal nanoclusters deposited on oxides have been widely used in photocatalysis playing an important role in the design of model catalysts with applications in heterogeneous catalysis. In particular, we are interested in the potential activity of these cluster-supported systems for the removal of nitrogen oxides either by possible catalytic reduction and/or by their adsorption. In this work, using first-principles methods, we evaluate the main characteristics of Agn (n = 1–4) nanoclusters isolated and deposited on anatase TiO2(101) and rutile TiO2(110) surfaces. Our results indicate that they are preferably adsorbed on rutile surface. The different formation energy at each surface can be explained using a Bader charge analysis. Particularly for Ag4 the lowest formation energy is obtained for tetrahedral geometry while the isolated Ag4 geometry is planar. Small silver deposits placed superficially on titania surfaces modify its electronic structures and improve the conduction band edges positions for possible NO reduction. Band edges positions with respect to the vacuum potential have been studied. The comparison of the conduction band minimum with the reduction potentials of NO/N2O and N2O/N2 shows that they are higher, being Ag3 on rutile and Ag1, Ag2 and Ag4P on anatase better for NO reduction. To complete the analysis, the calculation of work function, energy gap, ionization energy and electron affinity are relevant since they allow the location of semiconductor band edges at point of zero charge. Finally, the adsorption of nitrogen oxides is studied where the NO2 adsorption is favored over NO.

Confirming High-Valent Iron as Highly Active Species of Water Oxidation on the Fe, V-Coupled Bimetallic Electrocatalyst: In Situ Analysis of X-ray Absorption and Mössbauer Spectroscopy.

Iron (Fe)-based bimetallic oxides/hydroxides have been widely investigated for promising alkaline electrochemical oxygen evolution reactions (OERs), but it still remains argumentative whether Fe3+ or Fe4+ intermediates are highly active for efficient OER. Here, we rationally designed and prepared one Fe, V-based bimetallic composite nanosheet by employing the OER-inert V element as a promoter to completely avoid the argument of real active metals and using our recently developed one-dimensional conductive nickel phosphide (NP) as a support. The as-obtained hierarchical nanocomposite (denoted as FeVOx/NP) was evaluated as a model catalyst to gain insight into the iron-based species as highly active OER sites by performing in situ X-ray absorption spectroscopy and 57Fe Mössbauer spectroscopy measurements. It was found that the high-valent Fe4+ species can only be detected during the OER process of the FeVOx/NP nanocomposite instead of the iron counterpart itself. Together with the fact that the OER activities of both the vanadium and iron counterparts are by far worse than that of the FeVOx/NP composite, we can confirm that the high-valent Fe4+ formed are the highly active species for efficient OER. As demonstrated by density functional theory simulations, the composite of Fe and V metals is proposed to cause a decreased Gibbs free energy as well as theoretical overpotential of water oxidation with respect to its counterparts, as is responsible for its excellent OER performance with extremely low OER overpotential (290 mV at 500 mA cm-2) and extraordinary stability (1000 h at 100 mA cm-2).

Insight into the temperature-dependent SO2 resistance over Mn-based de-NOx catalyst

Herein, two simple model catalysts (Mn3O4 and MnFeOx) were fabricated and operated under different temperatures (100, 150, 200, 250 °C) in SCR atmosphere with the presence of SO2, followed by thermal regeneration and characterizations to reveal the deactivation mechanism and the role of FeOx. The results indicated both catalysts exhibited temperature-dependent deactivation behavior, where the total activity loss displayed volcano-type SO2 resistance tendency within 100–250 °C and the most severe activity loss (98 % for Mn3O4 and 81 % for MnFeOx) was found at 150 °C. Meanwhile, the higher relative proportion of irreversible activity loss was found at lower temperatures, which is associated with the more easily saturated chemical adsorption of SO2 as evidenced by SO2+O2 breakthrough test. At higher temperatures, the SO2 oxidation and its further transformation into NH4HSO4 could be favored, thus resulting in increased reversible activity loss. The FeOx modification can protect MnOx species from sulfation to a certain degree and lower the irreversible deactivation, which is evidenced by the binding energy upshift and downshift of Fen+ species after being poisoned and regenerated, as well as the slightly changed binding energy of Mnn+ species from the XPS analysis.