Abundant Acid Sites Research Articles

Tolerance of Cu-SSZ-13 catalysts to potassium sulfate: Strong Brønsted acid sites and copper species

Potassium sulfate is one of the most important impurities deposited on the NH3-SCR catalysts from alkali-rich gas exhausts. In this work, two Cu-SSZ-13 catalysts synthesized by one-pot and ion-exchange methods were compared for their tolerance to potassium sulfate. The evolutions of copper species and acid sites, as the critical mechanisms of K2SO4 poisoning, were revealed by comprehensive characterizations. It was found that Si-O(H)-Al sites act as sacrificing sites upon K+ attacking to preserve Cu2+ ions as active sites. ZCuOH sites are preferentially detached by K+ ion-exchange and trapped predominantly by the surface sulfate anions as inactive Cu2OSO4. Therefore, the one-pot Cu-SSZ-13, with abundant acid sites and high Z2Cu proportion, shows superior K2SO4 resistance than the ion-exchanged catalyst.

Cu/Fe-UZM-35 Catalysts for NOx Abatement in Diesel Vehicles for Next-Stage Emission Standards

Cu-based zeolite catalysts face the challenge of high N2O emissions, while Fe-based zeolite ones suffer from insufficient low-temperature activity and hydrothermal stability. To combat these issues, we developed Cu-Fe-coupled UZM-35 zeolite catalysts with NOx conversion over 85% in the temperature range of 175 °C. Meanwhile, over 80% of NOx can be converted between 150 and 550 °C. Furthermore, over 95% of N2 selectivity was obtained in the whole temperature range. Over these catalysts, Cu and Fe species were uniformly dispersed, being mostly in ionic forms; their presence hardly changed the framework and pore structure of the zeolite. Moreover, the Cu-Fe bimetallic zeolite contained abundant acid sites and even more active species, which ensured its superior catalytic performance for NOx reduction. In addition, the coupling of Cu and Fe stabilized both framework and active sites; therefore, superior hydrothermal stability was obtained. This study provides valuable insights for the development of SCR catalysts for diesel vehicles aimed at meeting future emission standards.

Robust core−shell ZIF-67@PDB-Br as synergetic catalyst for chemical fixation of CO2 without co-catalysts

Metal-organic frameworks (MOFs) are widely studied for cycloaddition of CO2 as a heterogeneous catalyst, because of their potential Lewis acidic sites and adjustable porous structure. However, most of them exhibit good catalytic performance need the assistance of nucleophilic co-catalysts. Herein, a novel MOFs and porous organic polymers (POPs) hybrid catalyst, core-shell ZIF-67@PDB-Br, is constructed by a convenient synthetic strategy, which possesses abundant Lewis acidic sites, imidazole cations and nucleophilic centers and shows robust chemical and thermal stability. This material demonstrates high-efficient catalytic activities and recyclability in the cycloaddition of CO2 and propylene oxide without co-catalysts, the conversion and selectivity can reach 94.1 % and 99.0 %, respectively (100 °C, 1.0 MPa CO2 pressure). Furthermore, the effects of the temperature, pressure, amount of catalyst and thickness of POPs shell on the catalytic activity were investigated. This study provides a viable direction for the development of synergistic heterogeneous catalysts for fixation of CO2 without co-catalysts.

Surface and morphology modulated adsorption-activation of trace concentration hydrogen peroxide with multiple electron transfer pathways and sustained Fenton reactions

To promote mass transfer and activation of hydrogen peroxide (H2O2) in Fenton-like reactions, a novel MOFs-derived Fe2O3 was tailor-designed through surface sulfur modification and morphology tuning for degrading a group of persistent micropollutants, i.e., sulfamethoxazole, enrofloxacin, and ofloxacin. The introduction of Ca2+ and Mg2+ modulated the growth of crystal clusters to prevent aggregation of Fe2O3 nanoparticles and provide more reaction sites. Likewise, the abundant acid sites (–SO3H) promote the chemisorption of even trace-concentration H2O2 (S–O bonding), whereas the S–Fe bonding accelerates electron transfer to promote the Fe3+/Fe2+ cycle and thus the H2O2 utilization. More interestingly, surface-adsorbed H2O is found to be activated to form •OH, due to electron-poor Fe sites formed after detachment of –SO3H, demonstrating a sustained radical yield for the micropollutant degradation. This study opens new perspectives in catalyst design to ultimately realize the utilization of trace-concentration H2O2 and even H2O in Fenton-like systems.

Exceptional proton conduction in two robust zirconium(IV)/hafnium(IV)-organic frameworks constructed by tetratopic carboxylate

The fabrication of metal-organic frameworks based on zirconium and hafnium with high structural rigidity using multifunctional carboxylate and the examination of their possible uses have gained significant attention in recent times. The structural features of these porous MOFs, such as their abundant Lewy acid sites and hydroxyl groups, which are appropriate for building effective proton transport channels, have also drawn much attention in the proton conduction field. Herein, two highly stable Zr(IV)/Hf(IV) MOFs, [M6(μ3-O)4(μ3-OH)4(bptc)3]·2DMF (M = Zr (Zr-bptc) or Hf (Hf-bptc)) were solvothermally prepared by employing the tetratopic ligand, 3,3′,5,5′-biphenyltetracarboxylic acid (H4bptc), in which M6(μ3-O)4(μ3-OH)4(COO)12 clusters are linked by bptc3- anions to form an ftw type framework with 12-connected M6 cluster. X-ray powder diffraction, infrared spectroscopy, scanning electron microscopy, and thermogravimetric analyses proved that the two MOFs had remarkable water, chemical, and thermal stability. The alternating current (AC) impedance determinations manifested that the two MOFs have high proton conductivities under 100 °C and 98 % relative humidity (RH) of 0.89 × 10−3 and 1.37 × 10−3 S/cm, respectively, which are among the described MOFs with high proton conductivity. Furthermore, the two MOFs demonstrated excellent electrochemical determination durability. In addition, the activation energy estimates at high or low RHs fully illustrated the significant influence of water molecules in the environment on proton transport within the framework. This investigation again confirms that Zr/Hf-based MOFs have unparalleled structural and performance advantages in energy chemistry.

Electronic synergy between NiCo2O4 and adjacent carbon defects to enhance styrene cracking activity for styrene-saturated activated carbon regeneration

The design and construction of catalysts featuring abundant electron transfer and defect structures for the regeneration of styrene-saturated activated carbon (AC) pose a significant challenge. This paper presents successful preparation of a regenerated adsorbent with synergistic catalytic active sites of NiCo2O4 spinel and carbon defects using a simple impregnation method. Enhanced catalytic activity is attributed to the electronic synergy between NiCo2O4 and carbon defects in 2.5Ni-2.5Co-900, involving substantial electron transfers, abundant acidic sites, and strong reducibility. Reactive oxygen species and the robust oxygen transfer facilitate the deep oxidation of intermediates and carbon elimination. The optimized regenerated adsorbent achieved a styrene adsorption capacity of 446.4 mg/g with a recovery of 92.4 % of the fresh sample, which is 1.5 times higher than 5Ni-900 and about 1.8 times higher than the unmodified regenerated activated carbon sample, RAC-900. The mechanism of styrene cracking and the evolution of intermediates were investigated using thermogravimetric-infrared coupling, and the effects of catalytic temperature and active sites on styrene cracking, deep oxidation of intermediates, and elimination of carbon deposits were explored. Kinetic analysis demonstrated that the adsorption of styrene on regenerated samples entailed a multifaceted process integrating both physical and chemical adsorption. The significance of chemical adsorption became increasingly evident as the concentration of defective sites grew. Intra-pore diffusion is the main determining step of the adsorption process. After five cycles, the adsorption capacity of 2.5Ni-2.5Co-900 decreased to below 25 %, suggesting promising strategies to overcome challenges of regenerating styrene-saturated AC.

Enhancing the electrochemical properties of polyethylene oxide solid-state electrolytes based on a small nano-sized UiO-66 metal-organic framework

Metal-organic frameworks (MOFs) have garnered significant attention in the field of Lithium-ion batteries due to their porous periodic network properties. However, this is a challenge to design high-performance solid-state electrolytes reasonably. Herein, a small nano-sized MOF Small-UiO-66 is reported, which has high surface area and mesoporous properties that can effectively inhibit PEO matrix crystallization. The presence of Small-UiO-66 accelerates the dissociation of lithium salts, which disrupts the ordered arrangement of the PEO chain segments. The abundant Lewis acidic sites on the surface of Small-UiO-66 facilitate the construction of abundant Li+ transport channels and promote Li+ conduction. Furthermore, the smaller nano-sized increase the interfacial wettability with lithium metal, which promotes the uniform diffusion of Li+ and inhibits the growth of lithium dendrites. The results indicate that 0.1 Zr-CSE exhibits high ionic conductivities of 6.94 × 10−4 S/cm at 60 °C. Based on 0.1 Zr-CSE, the Li||Li symmetric cell can operate stably for 1200 h at a current density of 0.1 mA/cm2, and the LFP||Li cell also achieves a high initial capacity of 147.65 mAh·g−1 at current densities of 0.5C. This work presents a novel approach for preparing high-performance solid-state Lithium-ion batteries using MOFs as fillers for polymer solid-state electrolytes.

Study on the synthesis of nanosheets petal-shaped ZSM-5 Zeolites

In this work, a novel strategy for hydrothermal synthesis of nanosheets petal-shaped ZSM-5 zeolites was introduced. The experimental results indicated that the nanosheets petal-shaped ZSM-5 zeolites exhibited a higher specific surface area and more abundant acid sites. Under the synergistic crystallization effect of ethanol and seeds, the addition of CTAB promoted the growth of the layered structure, and the introduction of trace amounts of seeds effectively inhibited the growth of mordenite in a high alkalinity environment, reducing the crystallization time to 48 hours. More importantly, the petal-shaped ZSM-5 zeolites exhibited excellent MTP (Methanol-to-Propylene) catalytic performance, with methanol conversion maintained above 97.8 % for 80 hours and a maximum propylene selectivity of 49.1 %. This paper proposes an Ethanol-Seed-CTAB synthesis method for producing petal-shaped ZSM-5 zeolite with a unique morphology. This approach does not require the use of complex gemini quaternary ammonium surfactants in the synthesis process, greatly promoting the application and dissemination of nanosheets zeolites.

Cutting the cost to combust methane by embellishing the Co-O-Cu interaction in Cu-incorporated Co3O4-based nanocatalysts

Ingredient control brings huge promise for fabricating high-performance Co3O4-based nanomaterials. Herein, for steering the microstructure and properties of Co3O4 system, copper components were incorporated into Co3O4 through a facile coprecipitation ploy taking n-butylamine as the precipitant. At fitting Cu-addition level, dual Co-O-Cu interactions were established by sharing oxygen species, which was based on the partial replacement of Co2+ by Cu2+ in Co3O4 lattice and creation of hetero-interfaces between surface dispersed CuO and Co3O4. Resultly, CH4 combustion efficiency on tailored catalysts was elevated by lessened crystalline sizes, higher dislocation density, preferable capability towards reduction, more abundant Lewis acidic sites, larger surface concentration of Co3+ sites, and the easy regeneration of active surface lattice oxygen contributed from richer O-vacancies. The above optimal attributes-induced supreme activity was accomplished on 0.4Cu-Co3O4 (molar ratio at 0.4), who was revealed to follow MvK CH4 combustion mechanistic model, and to manifest a decent long-term durability in anhydrous condition. Besides, results underscored that Cu-addition presented tiny contribution for water-resistance.

A Chemically Robust 2D Ni-MOF as an Efficient Heterogeneous Catalyst for One-Pot Synthesis of Therapeutic and Bioactive 2-Amino-3-Cyano-4H-Pyran Derivatives.

Despite possessing numerous catalytic advantages of MOFs, developing 2D frameworks having excellent chemical stability along with new catalytic properties, remains a grand challenge. Herein, by employing a mixed ligand synthetic approach, we have constructed a 2D Ni-MOF, IITKGP-52, which exhibits excellent framework robustness in open air, water, as well as over a wide range of pH solutions (2-12). Benefitting from its robustness and abundant Lewis acidic open metal sites, IITKGP-52 is explored in catalyzing the heterogeneous three-component condensation reaction for the tandem synthesis of bioactive 2-amino-3-cyano-4H-pyran derivatives with low catalytic loading, greater compatibility for a wide range of substrates, excellent recyclability and superior catalytic efficiency than the previously employed homo and heterogeneous systems. IITKGP-52inaugurates the employment of MOF-based catalysts for one-pot synthesis of therapeutic and bioactive 2-amino-3-cyano-4H-pyran derivatives.

Promoting metal oxides–zeolite electron interaction on MnCeOx/HY catalyst for boosting nitrogen oxides reduction

The MnOx-CeO2 metal oxides are considered as promising alternative catalysts for selective catalytic reduction with NH3 (NH3-SCR) to remove NOx due to its excellent low temperature performance. However, their strong oxidative ability can lead to NH3 over-oxidation, narrowing the active temperature range and reducing N2 selectivity. Moreover, their weak surface acidity hampers medium to high-temperature activity and alkali metal resistance. Hence, in this study, MnCeOx metal oxides were coupled with HY zeolite to create MnCeOx/HY, demonstrating excellent NH3-SCR performance. The high dispersion of metal oxides on the zeolite surface and their close integration promoted strong electron interaction, effectively reducing oxygen vacancies and surface adsorbed oxygen concentrations. Consequently, the oxidative ability of active metal oxides was appropriately weakened, suppressing undesirable side reactions. MnCeOx/HY also notably suppressed NO adsorption and nitrate formation, promoting the catalytic reaction solely through the E-R mechanism and enhancing N2 selectivity. The abundant strong acid sites on the zeolite surface facilitates NH3 adsorption at moderate to high temperatures, notably expanding the active temperature window. Furthermore, the acid sites of HY zeolite serve as sacrificial sites, preferentially reacting with alkali metals, thus exhibiting excellent resistance to alkali metal poisoning on MnCeOx/HY. Combining with the DFT results, the structure-activity relationships in this study also reveal the importance of the effective synergy between acid sites and redox sites for optimal catalytic performance, offering valuable insights into the development of highly active and alkali-resistant denitrification catalysts.

Enhancing acidity of Ru/Ce/ZrO2 bifunctional catalysts for promoting N2 selectivity in selective catalytic oxidation of NH3

To solve the problem of low N2 selectivity of Ru/Ce/ZrO2 (R/C/Z) catalysts in NH3 selective catalytic oxidation (NH3-SCO) reaction, herein ZrO2 supports were treated with sulfuric acid and its effects on NH3-SCO performance were investigated systematically. The results showed that Ru/Ce/ZrO2-10S (R/C/Z-10S) catalyst, in which the mass ratio of sulfuric acid to ZrO2 was 10 %, exhibited N2 selectivity of 95.7 % at 350 °C, that was significantly higher than R/C/Z catalyst (57.8 %). NH3-TPD tests indicated that sulfate treatment of ZrO2 supports in R/C/Z catalysts led to more abundant acidic sites on catalyst surface, which was in favor of enhancing NH3 adsorption capacity remarkably. But when mass ratio of sulfuric acid to ZrO2 increased up to 20 %, an aggregation of metal oxides on the surface of R/C/Z-20S catalyst could be observed clearly, which might impose an adverse impact on NH3-SCO performance. In-situ DRIFTS results revealed that, compared to R/C/Z catalyst, there were much more Brönsted acid sites on the surface of R/C/Z-10S catalyst, and the corresponding NH3 species on acidic sites could be consumed quickly in intermediate reactions. More importantly, amide (-NH2) species rather than imide (-NH) and nitrosyl (-HNO) species, were the majority on the surface of R/C/Z-10S catalyst, implying that there might be a suppressing effect on further dehydrogenation of -NH2 species into -NH species owning to sulfate treatment of ZrO2 supports in R/C/Z catalysts. Therefore, internal selective catalytic reduction (i-SCR) mechanism rather than -NH mechanism played a vital role in NH3-SCO reaction over R/C/Z-10S catalyst.

Oxygen-deficient layered ε-MnO2 nanosheets derived from acid-etched La3Mn2O7 for robust adsorption-catalytic oxidation of toluene

Manganese dioxide (MnO2) stands out as a promising catalyst for toluene degradation yet refining its synthesis for optimal efficiency poses a significant challenge. In this study, we presented an up-bottom synthesis approach for ε-MnO2 by selectively removing inactive La ions from La3Mn2O7 (LLM) through acid etching, yielding stacked nanosheets with enriched oxygen vacancies. The resulting H2SO4-LLM catalyst exhibited efficient synergistic adsorption-catalytic oxidation effects, attributed to its exceptional specific surface area (307.0 m2/g) and abundant acidic sites, achieving almost 90 % removal of 2000 mg/m3 toluene (T90) at 196 ℃ and complete oxidation to CO2 at 205 °C at a space velocity of 18000 mL/(g·h), outperforming most state-of-the-art catalysts for toluene removal. The study elucidates the role of lattice oxygen in catalyzing toluene oxidation and reveals the intricate interplay between oxygen adsorption, lattice oxygen mobility, and redox capability, paving the way for the development of robust catalysts for environmental remediation.

Regulation of oxygen vacancies in MnCO3-based catalysts by thermally inducing for efficiently catalytic benzene combustion

Tuning oxygen vacancies through carbon pyrolysis is an effective strategy for fabricating high-performance catalysts to oxidize volatile organic compounds (VOCs). Herein, a series of MnCO3-based catalysts were synthesized by pyrolyzing MnCO3 precursors with different morphologies including dumbbell-like (D), bayberry-like (B) and cubic (C) structures for the benzene oxidation. The catalyst (D-300) derived from dumbbell-like MnCO3 exhibited superior catalytic performance for the benzene oxidation with a T90 of 176 °C and remarkable stability in long-term, cycling and water-resistance tests. Abundant oxygen vacancies in D-300 improved lattice oxygen mobility and redox ability, resulting in superior oxygen uptake and release capabilities. Moreover, oxygen vacancies greatly facilitated the activation and replenishment of gaseous oxygens to generate active oxygen species, thereby dramatically accelerating the cleavage of benzene rings and deep mineralization. In situ DRIFTS analysis demonstrated that benzene preferentially adsorbed onto D-300 due to its abundant acidic sites, and the oxidation of phenolate species was a rate-determining step. H2O may hinder the activation of gaseous oxygen, suppressing the activity of the catalyst.

Catalytic Hydrolysis-Oxidation of Halogenated Methanes over Phase- and Defect-Engineered CePO4: Halogenated Byproduct-Free and Stable Elimination.

Catalytic elimination of halogenated volatile organic compound (HVOC) emissions was still a huge challenge through conventional catalytic combustion technology, such as the formation of halogenated byproducts and the destruction of the catalyst structure; hence, more efficient catalysts or a new route was eagerly desired. In this work, crystal phase- and defect-engineered CePO4 was rationally designed and presented abundant acid sites, moderate redox ability, and superior thermal/chemical stability; the halogenated byproduct-free and stable elimination of HVOCs was achieved especially in the presence of H2O. Hexagonal and defective CePO4 with more structural H2O and Brønsted/Lewis acid sites was more reactive and durable compared with monoclinic CePO4. Based on the phase and defect engineering of CePO4, in situ diffuse reflectance infrared Fourier transform spectra (DRIFTS), and kinetic isotope effect experiments, a hydrolysis-oxidation pathway characterized by the direct involvement of H2O was proposed. Initiatively, an external electric field (5 mA) significantly accelerated the elimination of HVOCs and even 90% conversion of dichloromethane could be obtained at 170 °C over hexagonal CePO4. The structure-performance-dependent relationships of the engineered CePO4 contributed to the rational design of efficient catalysts for HVOC elimination, and this pioneering work on external electric field-assisted catalytic hydrolysis-oxidation established an innovative HVOC elimination route.

High-efficient M-NC single-atom catalysts for catalytic ozonation in water purification: Performance and mechanisms

Heterogeneous catalytic ozonation (HCO) holds promise in water purification but suffers from limited accessible metal sites, metal leaching, and unclear structure-activity relationships. This work reported M-NC (M=Co, Ni, Fe, and Mn) single-atom catalysts (SACs) with high atomic efficiency and minimal metal release. The new HCO systems, especially the Co-based system, exhibited impressive performance in various refractory contaminant removal, involving various reactive species generation, such as •OHads, •OHfree, *O, and 1O2. For sulfamethoxazole removal, the normalized kobs for Co-NC, Ni-NC, Fe-NC, and Mn-NC were determined as 13.53, 3.94, 3.55, and 4.13 min−1·mMmetal−1·g·m−2 correspondingly, attributed to the abundant acid sites, faster electron transfer, and lower energy required for O3 decomposition and conversion. The metal atoms and hydroxyl groups, individually serving as Lewis and Bronsted acid sites (LAS and BAS), were the primary centers for •OH generation and O3 adsorption. The relationships between active sites and both O3 utilization and •OH generation were found. LAS and BAS were responsible for O3 adsorption, while strong LAS facilitated O3 conversion into •OH. Theoretical calculations revealed the catalytic mechanisms involved O3→ *O→ *OO→ O3•−→ •OH. This work highlights the significance of SAC design for HCO and advances the understanding of atomic-level HCO behavior.

Confinement and synergy effects of supported-confined bimetal catalysts with superior stability and catalytic activity

Bimetallic nanocrystals have attracted considerable attention because of their complicated systems, which are far superior to those of their individual constituents. A TiO2-confined PtMnP bimetallic catalyst (PtMnP@TiO2) was prepared using an ultrasonic-assisted coincident strategy, which demonstrated exceptional catalytic activity in the universal hydrogen evolution reaction (HER). Owing to the bimetallic synergistic effect and TiO2 confinement, PtMnP@TiOx showed ultrasmall metal nanoparticles (NPs), a higher active Pt0 content, adequate activation at the porous surface, and abundant acid sites. Simulations were performed to visualize the strain properties of Mn and Pt during the bending process and demonstrate the high activity of Pt. The Pt-Mn bimetallic catalysts were enriched with Pt NPs, convoyed by electron transfer from Mn to Pt. Briefly, PtMnP@TiO2 showed robust evolution reaction activities (an overpotential of 220 mV at a current density of 10 mA cm−2 and a Tafel slope of 186 mV dec−1) and the ability to contrast stated catalysts without ultrasonication-plasma. This protocol revealed that the geometrical and electronic effects of Pt and P surrounding the Mn species in PtMnP@TiO2 were crucial for increasing the catalytic activity (99%) and durability (over 20 cycles), which were far superior to those of other reported catalysts.

Enhancing sorption kinetics by oriented and single crystalline array-structured ZSM-5 film on monoliths

To enhance the reaction kinetics without sacrificing activity in porous materials, one potential solution is to utilize the anisotropic distribution of pores and channels besides enriching active centers at the reactive surfaces. Herein, by designing a unique distribution of oriented pores and single crystalline array structures in the presence of abundant acid sites as demonstrated in the ZSM-5 nanorod arrays grown on monoliths, both enhanced dynamics and improved capacity are exhibited simultaneously in propene capture at low temperature within a short duration. Meanwhile, the ZSM-5 array also helps mitigate the long-chain HCs and coking formation due to the enhanced diffusion of reactants in and reaction products out of the array structures. Further integrating the ZSM-5 array with Co3O4 nanoarray enables comprehensive propene removal throughout a wider temperature range. The array structured film design could offer energy-efficient solutions to overcome both sorption and reaction kinetic restrictions in various solid porous materials for various energy and chemical transformation applications.

Effect of different ligands on the preparation of Pt-xMn@HZSM-5 and their catalytic performance for iso-butane catalytic cracking

ZSM-5 has emerged as a promising catalyst for iso-butane catalytic cracking due to its unique pore structures and abundant acid sites. And the optimization of catalytic performance has attracted more and more attention. Herein, a series of Pt and Mn-embedded Pt-xMn@HZSM-5 catalysts with different Mn complexes were successfully synthesized via the one-pot hydrothermal method (x refers to the Mn/Pt ratio). The ligand effects of both ethylenediamine and ethylenediaminetetraacetic acid disodium salt on the nature of target samples in terms of crystallinity, porosity, morphology, metal state, and acidity, were investigated in detail. It has been demonstrated that ethylenediamine served as a ligand enabled Pt-xMn@HZSM-5 more metal nanoparticles and acid sites, thereby delivering improved catalytic performance and high yields of ethylene, propylene and BTX (benzene, toluene, and xylene) for iso-butane catalytic cracking.

Enhanced low-temperature activity of Mn-based catalysts for NH3 selective catalytic reduction of NO through Ce-modulated redox and TiO2 shell construction

Manganese-based catalysts presented great challenges for the wide operating window in the selective catalytic reduction of NOx with NH3 (NH3-SCR). Aiming at enhancement of the SCR performance, a series of MnCeOx (MnyCe1) and Mn1Ce1@TiO2 catalysts were prepared. Impressively, the Mn1Ce1 catalyst exhibited excellent low-temperature activity, achieving over 80 % conversion of NO within the temperature range of 85–350 °C, but the N2 selectivity decreased with the increasing temperature. Upon coating a TiO2 shell, the temperature window with N2 selectivity exceeding 80 % was significantly widened to 85–350 °C since the weak redox ability limited the NH3 oxidation to undesired N2O. High surface area, together with abundant acid sites and chemical adsorbed oxygen that formed via the interaction between Mn4+/Mn3+, Ce4+/Ce3+ and Ti4+/Ti3+, contributed to the superior catalytic performance of Mn1Ce1@TiO2. In addition, through in situ DRIFTS analysis, both Eley-Rideal and Langmuir-Hinshelwood reaction routes were observed. This work would provide an efficient and low-cost strategy for preparing Mn-based catalysts with excellent low-temperature activity for NOx removal.