Superior Low-temperature Activity Research Articles

CoZnyB/Nb2CTx(MXene) for cinnamaldehyde hydrogenation to cinnamyl alcohol: Effects of Zn

Amorphous cobalt boride (CoB) catalysts have superior CO selectivity for cinnamaldehyde (CAL) hydrogenation and low activity. This work prepared CoZnyB/Nb2CTx(MXene) catalysts with different Zn ratios (y=0, 0.025, 0.05, 0.075, and 0.1) via a wet reduction method, which were subsequently utilized in the selective hydrogenation of CAL to cinnamyl alcohol (COL). The CoZn0.05B/Nb2CTx catalyst exhibited superior low-temperature activity, with 91.4 % CAL conversion and a 66.3 % COL yield. SEM and XPS analyses further revealed that Zn enhanced the catalytic activity by generating smaller amorphous alloy particles and exposing more Co0 active sites. Furthermore, the NH3-TPD and adsorbed pyridine DRIFTS results showed that Zn modified the surface acidity of the CoZnyB/Nb2CTx catalyst by generating both Lewis acid sites and Brønsted acid sites, which can facilitate the adsorption of CAL. This work demonstrated that Zn can increase the number of exposed active sites and modify the surface acid properties of amorphous CoB catalysts.

Advancements in cobalt‐based oxide catalysts for soot oxidation: Enhancing catalytic performance through modification and morphology control

AbstractThe widespread use of diesel engines results in significant environmental contamination due to emitted pollutants, particularly soot particles. These pollutants are detrimental to public health. At present, one of the most effective ways to remove soot particles is the catalytic diesel particulate filter after‐treatment technology, which requires the catalyst to have superior low temperature activity. Compared with cerium oxide which is widely used, cobalt oxide in transition metal oxides has been widely studied in recent years because of its high redox ability and easy to control morphology. This paper elaborates on the influence of modification techniques such as doping, loading, and solid solution on the catalytic performance of cobalt‐based catalysts in soot oxidation. Along the same lines, it further reviews the research progress on cobalt‐based oxide catalysts with specific dimensional structures and morphologies in soot oxidation. Finally, it provides an outlook on the challenges faced by the theoretical basis and applied research of cobalt‐based catalysts in soot oxidation.

Enhanced denitrification performance of Mo/Mn co-doped 5 %Fe/TiO2 catalysts via citric acid-assisted impregnation

This study investigates the denitrification performance of Fe5Mn3Mo3/TiO2 catalysts prepared using citric acid-assisted impregnation (CA) and conventional impregnation (IM) methods in the context of NH3-selective catalytic reduction (SCR) reaction. Specifically, the influence of citric acid quantity on the catalytic activity is studied, with a special emphasis on Fe5Mn3Mo3/TiO2-0.5CA variant. Our results demonstrate that Fe5Mn3Mo3/TiO2-0.5CA exhibits superior low-temperature activity and prolonged stability compared to the conventional impregnation method. Remarkably, operating temperature window based on 80 % denitrification activity is T80 = 190–405 °C. Furthermore, the Fe5Mn3Mo3/TiO2-0.5CA maintains a noteworthy 98 % NO conversion at 300 °C for a duration of 100 hours. The excellent performance is attributed to the highly dispersed nature of the active species, the large specific surface area, the low apparent activation energy, and a robust interaction between the active components and the substrate. XPS analysis reveals a significantly higher Oα/(Oα+Oβ) ratio for Fe5Mn3Mo3/TiO2-0.5CA, underscoring the effectiveness of citric acid modification in promoting the formation of Fe2+ species. This research provides valuable insights into the design and optimization of catalysts for efficient denitrification processes.

Effect of Mn or Fe on CrMoOx /TiO2 selective catalytic reduction catalyst

Developing a high-efficiency catalyst with both superior low-temperature activity and good sulfur and water resistance is still challenging for the NH3 selective catalytic reduction (SCR). Herein, a series of Mn- and Fe-doped CrMoOx/TiO2 catalysts were elaborately designed and the Cr3Mo6Mn2/TiO2 catalyst exhibits the best NOx conversion rate, reaching 81. 8 % at 90 ℃ and closing to 100 % at 150 ℃, and the NOx conversion reach ∼71 % at 150 ℃ for 30 h in presence of H2O+SO2. A series of characterization studies revealed that the abundance of Lewis acidic sites on the catalysts and the protective effect of Mo are conducive to the enhancement of SO2+H2O resistance. cr3Mo6Mn2/TiO2 dominates the SCR reaction through the Eley-Rideal (E-R) pathway between adsorbed NH4+/NH3 and gaseous NOx, generating N2 and H2O. This work provides a new strategy for improving the tolerance of chromium-based oxide catalysts to sulfur dioxide and water at low temperatures.

Advancing highly selective low-temperature ammonia oxidation: Hydrophobic silicalite-1 shell confining silver nanoparticles on Cu/ZSM-5 core

A judiciously devised core–shell NH3-SCO catalyst featuring a Cu/ZSM-5 core enveloped by an Ag/silicalite-1 shell (Cu/ZSM-5@Ag/S-1) was rationally constructed. Integrating the silicalite-1 shell effectively suppresses the migration of Ag into Cu/ZSM-5 core, conserving the active Cu2+ sites for the catalytical conversion of byproducts NOx. Concurrently, the shell averts the formation of positively charged Ag species, facilitating the generation of abundant Ag0 nanoparticles encapsulated in the S-1 shell. Comprehensive characterizations reveal abundant Ag0 species within the core–shell Cu/ZSM-5@Ag/S-1 catalyst, boosting O2 activation and NH3 dehydrogenation and thereby contributing to superior low-temperature activity in NH3-SCO reactions. Furthermore, the hydrophobic S-1 shell effectively reinforces the hydrothermal stability of the core–shell Cu/ZSM-5@Ag/S-1. DRIFTS coupled with DFT studies elucidate that the core–shell sample follows the imide mechanism, while the shell-free sample adheres to the hydrazine mechanism. This work advances our understanding of catalyst design and presents a promising solution with practical implications for ammonia oxidation processes.

Efficacious destruction of typical aromatic hydrocarbons over CoMn/Ni foam monolithic catalysts with boosted activity and water resistance

Developing cost-effective monolith catalyst with superior low-temperature activity is critical for oxidative efficacious removal of industrial volatile organic compounds (VOCs). However, the complexity of the industrial flue gas conditions demands the need for high moisture tolerance, which is challenging. Herein, CoMn–Metal Organic Framework (CoMn–MOF) was in situ grown on Ni foam (NiF) at room temperature to synthesize the cost-effective monolith catalyst. The optimized catalyst, Co1Mn1/NiF, exhibited excellent performance in toluene oxidation (T90 = 239 °C) due to the substitution of manganese into the cobalt lattice. This substitution weakened the Co–O bond strength, creating more oxygen vacancies and increasing the active oxygen species content. Additionally, experimentally and computationally evidence revealed that the mutual inhibiting effect of three typical aromatic hydrocarbons (benzene, toluene and m–xylene) over the Co1Mn1/NiF catalyst was attributed to the competitive adsorption occurring on the active site. Furthermore, the Co1Mn1/NiF catalyst also presents outstanding water resistance, particularly at a concentration of 3 vol%, where the activity is even enhanced. This was attributed to the lower water adsorption and dissociation energy derived from the interaction between the bimetals. Results demonstrate that the dissociation of water vapor enables more reactive oxygen species to participate in the reaction which reduces the formation of intermediates and facilitates the reaction. This investigation provides new insights into the preparation of oxygen vacancy–rich monolith catalysts with high water resistance for practical applications.

Synergistic roles of Ru, CeO2, and HZSM-5 in a ternary-active center catalyst for catalytic destruction of dichloromethane

Developing well-qualified industrial catalysts with excellent oxidation ability, selectivity, and resistance is still a challenge for chloroalkane destruction. Herein, we optimized the composition of multi-component catalysts with diverse active sites to adjust their acidic and redox properties for reasonable catalytic performance. The synergy of redox center Ru, activation center CeO2, and acid center HZSM-5 endowed the ternary catalyst Ru/CeO2/HZSM-5 with superior low-temperature activity (30 ∼ 60 °C lower for 50 % conversion), promoted stability and chlorine tolerance (100 % conversion for at least 30 h), and less toxic by-products for dichloromethane (DCM) destruction compared with the binary ones, promising for industrial application under tough conditions (e.g., thermal shock, HCl, H2O). The strong interaction of Ru and CeO2 enhanced the redox property of Ru/CeO2/HZSM-5 and thus promoted the deep oxidation of DCM and intermediates, thereby generating more CO2 and less dechlorinated by-products (e.g., CH3Cl). The synergistic effects of Ru, CeO2, and HZSM-5 facilitated chlorine removal and suppressed the generation of polychlorinated by-products (e.g., CHCl3) over the Ru/CeO2/HZSM-5 catalyst by improving redox capacity and inhibiting reactivity of chlorine. Notably, the introduction of CeO2 weakened the hydrophilicity of Ru and HZSM-5, improving the water resistance of the catalyst. The corresponding monolithic catalyst could achieve complete oxidation of DCM at 400 °C with the total concentration of dioxins measured at 0.026 ng I-TEQ kg−1 after continuous operation at 250 °C for 30 h.

Superior low temperature activity over α-MnO2/β-MnOOH catalyst for selective catalytic reduction of NO x with ammonia.

Manganese octahedral molecular sieves with an α-MnO2 crystal structure (OMS-2) and their related materials have attracted significant attention for the selective catalytic reduction of NO x using NH3 (NH3-SCR) at low temperatures. Further lowering their operating temperature should be an effective method to develop an environmentally friendly de-NO x system; however, their catalytic activity at low temperatures, especially below 100 °C, remains poor. This study describes a post-synthetic approach to develop Mn-based catalysts superior to those in the literature that operate at ultralow temperatures. Post-synthetic planetary ball milling for OMS-2 caused the partial conversion of OMS-2 into β-MnOOH. The obtained nanocomposite catalysts possessed abundant surface oxygen vacancies and strong surface acidity, allowing the milled catalyst to exhibit higher NO conversion at 90 °C (91%) than that in freshly prepared OMS-2 without planetary ball milling (29%). Lowering the operation temperature of OMS-2 catalysts contributed to the suppression of N2O evolution during NH3-SCR over manganese-based catalysts, resulting in high N2 selectivity over the milled OMS-2 catalyst (93%).

Hydrogen Spillover Induced PtCo/CoOx Interfaces with Enhanced Catalytic Activity for CO Oxidation at Low Temperatures in Humid Conditions.

The development of catalysts with abundant active interfaces for superior low-temperature catalytic CO oxidation is critical to meet increasingly rigorous emission requirements, yet still challenging. Herein, this work reports a PtCo/CoOx/Al2O3 catalyst with PtCo clusters and enriched Pt─O─Co interfaces induced by hydrogen spillover from the Pt sites and self-oxidation process in air, exhibiting excellent performance for CO oxidation at low temperatures and humid conditions. The combination of structural characterizations and in situ Fourier transform infrared spectroscopy reveals that the PtCo cluster effectively prevents CO saturation/poisoning on the Pt surface. Additionally, the presence of Pt─O─Co interfaces in the PtCo/CoOx/Al2O3 catalyst provides a significant number of active sites for oxygen activation and ─OH formation. This facilitates efficient generation of CO2 at ambient temperature by coupling with nearby adsorbed CO molecules, resulting in superior low-temperature activity and long-term stability for CO oxidation under humid conditions. This work provides a facile route toward rationalizing the design of catalysts with more active interfaces for superior low-temperature CO oxidation under humid conditions for practical applications.

Understanding enhancement of strong Copper-Yttrium interactions on catalytic properties of Cu/Y-SSZ-13 for NH3-SCR

Cu-SSZ-13 represents one of the most promising catalysts for selective catalytic reduction of NOx with ammonia (NH3-SCR), but it has remained challenging to gain superior low-temperature activity and hydrothermal stability for meeting the stringent emission regulations. Here, Cu/Yx-SSZ-13 have been prepared by in situ doping of Y and subsequent ion-exchanging with Cu ions. The combined analysis of various energy spectra techniques unveils that Y ions are mainly located in the six-membered rings (6MRs) of chabazite framework and have a strong interaction with Cu cations in 8MRs, resulting in the remarkable low-temperature NOx abatement efficiency and hydrothermal stability. Mechanism studies reveal that the interplay between Y and Cu not only enhances the electron transfer from Cu to Y ions that favors the ammonia solvation process and reduces the reaction barrier, but also inhibits the aggregation of Cu sites. This work paves the way for next generation of advanced NH3-SCR catalysts.

Water-tolerant and anti-dust CeCo-MnO2 membrane catalysts for low temperature selective catalytic reduction of nitrogen oxides

The present work successfully proposes a domain knowledge–guided Machine Learning (ML) strategy, which successes the development of a water-tolerant anti-dust catalyst for Low-Temperature (LT) Selective Catalytic Reduction (SCR) of nitrogen oxides (NOx) from catalyst discovery to industrial deployment. The discovered catalyst is able to convert 99 % of NOx at 150 °C in the standard waste gas, even in the waste gas containing 7 vol% of water vapors, the efficiency is still retained at 97 %. The superior LT activity and water-tolerance are attributed to abundant surface-active oxygen, Brønsted acid and microcellular structure. The SCR reaction mainly follows the Eley-Rideal (E-R) pathway driven by Brønsted acid and the Langmuir-Hinshelwood (L-H) pathway maintained by abundant reactive oxygen species in moisture waste gases. And then, catalyst is synthesized on a polyphenylene sulfide filter to render the membrane configuration in order to have the anti-dust ability. The final membrane catalyst has the capacity of converting 95 % NOx in the waste gas containing 7 vol% of moisture at 150 °C and the dedusting, and denitrification ability. The domain knowledge–guided Machine Learning (ML) strategy paves a wide avenue for the whole chain development from the data-driven discovery to the industrial deployment associated with mechanism exploration.

Redox-Induced In Situ Growth of MnO2 with Rich Oxygen Vacancies over Monolithic Copper Foam for Boosting Toluene Combustion.

Catalytic combustion has been known to be an effective technique in volatile organic compound (VOC) abatement. Developing monolithic catalysts with high activity at low temperatures is vital yet challenging in industrial applications. Herein, monolithic MnO2-Ov/CF catalysts were fabricated via the in situ growth of K2CuFe(CN)6 (CuFePBA, a family of metal-organic frames) over copper foam (CF) followed by a redox-etching route. The as-synthesized monolith MnO2-Ov-0.04/CF catalyst displays a superior low-temperature activity (T90% = 215 °C) and robust durability for toluene elimination even in the presence of 5 vol % water. Experimental results reveal that the CuFePBA template not only guides the in situ growth of δ-MnO2 with high loading over CF but also acts as a source of dopant to create more oxygen vacancies and weaken the strength of the Mn-O bond, which considerably improves the oxygen activation ability of δ-MnO2 and consequently boosts the low-temperature catalytic activity of the monolith MnO2-Ov-0.04/CF toward toluene oxidation. In addition, the reaction intermediate and proposed mechanism in the MnO2-Ov-0.04/CF mediated catalytic oxidation process were investigated. This study provides new insights into the development of highly active monolithic catalysts for the low-temperature oxidation of VOCs.

Revealing the Excellent Low-Temperature Activity of the Fe1–xCexOδ-S Catalyst for NH3-SCR: Improvement of the Lattice Oxygen Mobility

The development of selective catalytic reduction catalysts by NH3(NH3-SCR) with excellent low-temperature activity and a wide temperature window is highly demanded but is still very challenging for the elimination of NOx emission from vehicle exhaust. Herein, a series of sulfated modified iron-cerium composite oxide Fe1-xCexOδ-S catalysts were synthesized. Among them, the Fe0.79Ce0.21Oδ-S catalyst achieved the highest NOx conversion of more than 80% at temperatures of 175-375 °C under a gas hourly space velocity of 100000 h-1. Sulfation formed a large amount of sulfate on the surface of the catalyst and provided rich Brønsted acid sites, thus enhancing its NH3 adsorption capacity and improving the overall NOx conversion efficiency. The introduction of Ce is the main determining factor in regulating the low-temperature activity of the catalyst by modulating its redox ability. Further investigation found that there is a strong interaction between Fe and Ce, which changed the electron density around the Fe ions in the Fe0.79Ce0.21Oδ-S catalyst. This weakened the strength of the Fe-O bond and improved the lattice oxygen mobility of the catalyst. During the reaction, the iron-cerium composite oxide catalyst showed higher surface lattice oxygen activity and a faster replenishment rate of bulk lattice oxygen. This significantly improved the adsorption and activation of NOx species and the activation of NH3 species on the catalyst surface, thus leading to the superior low-temperature activity of the catalyst.

Simultaneously Constructing Active Sites and Regulating Mn-O Strength of Ru-Substituted Perovskite for Efficient Oxidation and Hydrolysis Oxidation of Chlorobenzene.

Chlorinated volatile organic compounds (CVOCs) are a class of hazardous pollutants that severely threaten environmental safety and human health. Although the catalytic oxidation technique for CVOCs elimination is effective, enhancing the catalytic efficiency and simultaneously inhibiting the production of organic byproducts is still of great challenge. Herein, Ru-substituted LaMn(Ru)O3+ δ perovskite with Ru-O-Mn structure and weakened Mn-O bond strength has been developed for catalytic oxidation of chlorobenzene (CB). The formed Ru-O-Mn structure serves as favorable sites for CB adsorption and activation, while the weakening of Mn-O bond strength facilitates the formation of active oxygen species and improves oxygen mobility and catalyst reducibility. Therefore, LaMn(Ru)O3+ δ exhibits superior low-temperature activity with the temperature of 90% CB conversion decreasing by over 90°C compared with pristine perovskite, and the deep oxidation of chlorinated byproducts produced in low temperature is also accelerated. Furthermore, the introduction of water vapor into reaction system triggers the process of hydrolysis oxidation that promotes CB destruction and inhibits the generation of chlorinated byproducts, due to the higher-activity *OOH species generated from the dissociated H2 O reacting with adsorbed oxygen. This work can provide a unique, high-efficiency, and facile strategy for CVOCs degradation and environmental improvement.

Highly active Ni/CeO2/SiO2 catalyst for low-temperature CO2 methanation: Synergistic effect of small Ni particles and optimal amount of CeO2

CO2 methanation is of great significance to CO2 utilization. However, it is challenging to prepare Ni-based catalysts with superior low-temperature activity via a simple method. In this work, a highly active Ni/CeO2/SiO2 catalyst is developed by a combustion-impregnation method, and the synergistic effect of active sites for H2 and CO2 activation are studied. The research results show that highly dispersed Ni particles (6 nm) are obtained by this method with an instantaneous reaction. As a result of the increased number of Ni active sites, the catalyst exhibits improved catalytic activity. Moreover, addition of CeO2 promoter further improves the low-temperature activity. First, it enhances the catalyst reducibility, creating more Ni active sites for H2 dissociation. Second, the surface oxygen vacancies formed on CeO2 facilitate CO2 activation. Therefore, the best performance of 63% CO2 conversion and 99% CH4 selectivity at 250 °C is achieved on the Ni-5Ce catalyst with small Ni particles and optimal amount of CeO2 promoter. With higher CeO2 content, Ni-7.5Ce catalyst displays decreased catalyst reducibility and catalytic activity. Therefore, it can be concluded that a proper ratio between both types of sites is crucial for CO2 methanation.

Insight into the promoting effect of support pretreatment with sulfate acid on selective catalytic reduction performance of CeO2/ZrO2 catalysts

In this paper, sulfated ZrO2 were synthesized via precipitation and impregnation method, and the promoting effects of support sulfation on selective catalytic reduction (SCR) performance of CeO2/ZrO2 catalysts were investigated. The results revealed that sulfated ZrO2 could significantly enhance the SCR activity of CeO2/ZrO2 catalysts in a wide temperature range. Especially when S/Zr molar ratio was 0.1, CeO2/ZrO2-0.1S catalyst exhibited a large operating temperature window of 251 ∼ 500 °C and its N2 selectivity was 100 % in the temperature range of 150 ∼ 500 °C. Moreover, CeO2/ZrO2-0.1S catalyst possessed a superior low-temperature activity over 0.1S-CeO2/ZrO2 catalyst. After exposing to 100 ppm SO2 for 15 h, a high NO conversion efficiency of CeO2/ZrO2-0.1S catalyst (90.7 %) could still be reached. The characterization results indicated that ZrO2 treated with a proper dosage of sulfate acid was beneficial to enlarge the specific surface area greatly. Sulfated ZrO2 was also in favor of promoting the transformation of CeO2 from crystalline state to highly-dispersed amorphous state, and inhibiting the transformation of ZrO2 from tetragonal to monoclinic phase. It could also enhance the total surface acidity greatly with an increase in both Brønsted acid sites and Lewis acid sites, thus significantly improving NH3 adsorption on catalyst surface. Besides, the promoting effect of support sulfation on SCR performance of CeO2/ZrO2 catalysts was also related with the enhanced redox property, higher Ce3+/(Ce3++Ce4+) ratio and abundant surface chemisorbed labile oxygen. The in-situ DRIFTS results implied that nitrate species coordinated on the surface of CeO2/ZrO2-0.1S catalyst could participate in the Selective catalytic reduction with ammonia (NH3-SCR) reactions at either medium or high temperature, suggesting that both Eley-Rideal (E-R) and Langmuir-Hinshelwood (L-H) mechanisms might be followed in SCR reactions.

Highly Active and Stable Palladium Catalysts on Novel Ceria-Alumina Supports for Efficient Oxidation of Carbon Monoxide and Hydrocarbons.

Precious metal catalysts with superior low-temperature activity and excellent thermal stability are highly needed in environmental catalysis field. In this work, a novel two-step incipient wetness impregnation (T-IWI) method was developed for the fabrication of a unique and highly stable CeO2/Al2O3 support (CA-T). Pd anchored on CA-T exhibited a much higher low-temperature catalytic activity and superior thermal stability in carbon monoxide (CO) and hydrocarbon (HC) oxidations, compared to Pd anchored on conventional CeO2/Al2O3 (CA), which was prepared by a one-step IWI method. After aging treatment at 800 °C, the CO oxidation rate on Pd/CA-T (1.69 mmol/(gPd s)) at 120 °C was 4.1 and 84.5 times of those on Pd/CA (0.41 mmol/(gPd s)) and Pd/Al2O3 (0.02 mmol/(gPd s)), respectively. It was revealed that the CA-T support with well-controlled small CeO2 particles (ca. 12 nm) possessed abundant defects for Pd anchoring, which created rich Pd-CeO2 interfaces with strengthened interaction between Pd and CeO2 where oxygen could be efficiently activated. This resulted in the significantly improved oxidation activity and thermal stability of Pd/CA-T catalysts. The T-IWI method developed herein can be applied as a universal approach to prepare highly stable metal oxide-alumina-based supports, which have broad application in environmental catalyst design, especially for automobile exhaust aftertreatment.

Effects of binary Co–Mn oxides promoters on low-temperature catalytic performance of Pd/Al2O3 for methane combustion

Aiming at fabricating high-activity and stable methane combustion catalysts in the dry/wet conditions, Co–Mn binary oxides were employed as promoters to Pd/Al2O3 system herein. The introduction of appropriate amount of manganese made Mn3+ maximally enter into the Co3O4 spinel structure, conducive to the conversion of Co3+ to Co2+ by Mn3+ and then the enhancement of lattice distortion. Therefore, abundant oxygen vacancies were produced, which enhanced the surface-concentrations of active Pd2+ and Oads species, together with the exchange of oxygen species. The resulting catalyst with a molar Mn/Co ratio of 0.20 performed superior low-temperature activity and durability. Moreover, the synergy of Mn and Co could accelerate the removal process of accumulated OH/H2O from the active sites, thereby promoting the regeneration of PdO and oxygen vacancies. This endowed the tailored catalyst with remarkable moisture-tolerance and hydrothermal stability, and inspiring enhanced activity (T90 = 350 °C) after removing water vapor.

Structures and catalytic performances of Me/SAPO-34 (Me = Mn, Ni, Co) catalysts for low-tem perature SCR of NOx by ammonia

Me/SAPO-34 (Me = Mn, Ni, Co) series of catalysts were prepared by a wetness impregnation method and investigated for the selective catalytic reduction of nitrogen oxides with ammonia (NH3-SCR). Among them, Mn/SAPO-34 catalyst was found as the most promising candidate based on its superior low-temperature activity. The catalysts were characterized by X-ray diffraction (XRD), transmission electron microscopy images (TEM), nuclear magnetic resonance (NMR), X-ray photoelectron spectroscopy (XPS), temperature programmed reduction and desorption (TPR and TPD), and diffuse reflectance infrared Fourier transformed spectroscopy (DRIFTS) of NH3/NOx adsorption. Mn/SAPO-34 is obviously different from Ni/SAPO-34 and Co/SAPO-34 in the active species state and distribution. Surface MnOx species which play an essential role in NO oxidation and NO2 adsorption, act as better active sites than nickel and cobalt mostly in the form of the aluminates and silicates.

A highly active VOx-MnOx/CeO2 for selective catalytic reduction of NO: The balance between redox property and surface acidity

Excellent catalysts with low-temperature activity and relatively wide temperature window for selective catalytic reduction of NO with ammonia (NH3-SCR) are highly demanded in view of the practical treatment of NO. Herein, we have designed a highly active VOx-MnOx/CeO2 material based on the intrinsic requirement of SCR reaction for catalyst, namely redox sites and surface acid sites. The vanadium oxide and manganese oxide are highly dispersed over the ceria mesosphere via simple incipient wetness impregnation. The loading of manganese could introduce acid sites and enhance the redox property remarkably, while the loading of vanadium increases acid sites and weakens redox property. Through tentatively controlling the appropriate loading ratio of the two components, the optimal catalyst achieves a balance between redox property and surface acidity. The work shed light on the development of new SCR catalyst with superior low temperature activity, wide work temperature window and good hydrothermal stability.