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Simultaneously elimination of NO and CO in the sintering flue gas is an urgent problem, in which the application of the bifunctional MnO x catalyst has demonstrated its effectiveness in removing NO and CO simultaneously. Potassium salts are frequently found in the sintering flue gas and exert a detrimental influence on the catalytic performance of catalysts. Herein, the primary focus of this study is to investigate different K+ species (K 2 SO 4 , KCl, KNO 3) poisoning effect on bifunctional MnO x. The findings suggested a deactivation order in the sequence of KNO 3 > KCl > K 2 SO 4. Fresh Mn-AC catalyst had finer grains, and poisoning elements were evenly distributed. XPS results revealed an obvious decrease in Mn4+ and O β species across all catalysts after K+ species poisoning, hindering redox cycle activation and oxygen species mobility, thus impacting catalytic activity. The in situ DRIFTS results indicated the forbidden of E-R route over KNO 3 -poisoned catalysts and low reactivity of adsorbed species after poisoning for NO removal. KNO 3 severely suppressed surface reaction paths on Mn-AC catalyst and declined the catalytic efficiency, especially in CO activation. Finally, a possible reaction mechanism model for the simultaneous removal of NO and CO was proposed. This study could provide reference for the development of bifunctional catalyst with high resistance to potassium salts. • Fresh and K-poisoned Mn-AC catalysts were synthesized by combining PEG-assited co-precipitation and impregnation methods. • The poisoning sequence of Mn-AC catalyst was followed as K 2 SO 4 < KCl

Abstract: A comprehensive study was carried out on amorphous metal‐organic frameworks Mn‐MIL‐100 as efficient catalysts for CO oxidation. This study focused on explaining the crystalline–amorphous–crystalline transformations during thermolysis of Mn‐MIL‐100 and studying the structure changes during the CO oxidation reaction. A possible formation mechanism of amorphous Mn‐MIL‐100 was proposed. Amorphous Mn‐MIL‐100 obtained by calcination at 250 °C (a‐Mn‐250) showed a smaller specific surface area (4 m2 g−1) but high catalytic activity. Furthermore, the structure of amorphous Mn‐MIL‐100 was labile during the reaction. When a‐Mn‐250 was treated with reaction atmosphere at high temperature (giving used‐a‐Mn‐250‐S), the amorphous catalysts transformed into Mn2O3. Meanwhile, the BET surface area (164 m2 g−1) and catalytic performance both sharply increased. In addition, used‐a‐Mn‐250‐S catalyst transformed from Mn2O3 into Mn3O4, and this resulted in a slight decrease of catalytic activity in the presence of 1 vol % water vapor in the feed stream. A schematic mechanism of the structure changes during the reaction process was proposed. The success of the synthesis relies on the increase in BET surface area by using CO as retreatment atmosphere, and the enhanced catalytic activity was attributed to the unique structure, a large quantity of surface active oxygen species, oxygen vacancies, and good low‐temperature reduction behavior. [ABSTRACT FROM AUTHOR]

Mesostructured ACeO x (A = Co, Cu, Fe, Mn, or Zr) composites with large specific surface area and developed mesoporosity were prepared by inorganic metal precursor spontaneous precipitation (IMSP) method. Influences of catalyst surface area, pore structure, reducibility, and active oxygen concentration on catalytic performance were studied. Both preparation route and metal precursor type affect metal active site dispersion, and the IMSP is a desirable approach for synthesis of metal composites with homogeneous active phase distribution. The original crystalline structure of CeO 2 is well maintained although parts of transition metal cations are incorporated into its framework. The forming of A n + –O 2 − –Ce 4 + connections in ACeO x catalysts could reduce the redox potential of metal species, allowing effective redox cycles during oxidation reactions. CuCeO x demonstrates powerful catalytic efficiency with 99% of chlorobenzene (CB) destructed at 328 °C, which is much lower than the other ACeO x oxides and Cu-doped catalysts synthesized via the incipient impregnation and coprecipitation methods (T 99 > 405 °C). The active site reducibility is the foremost activity determining factor for CB destruction. [ABSTRACT FROM AUTHOR]

Highlights: [•] A facile and universal self-precipitation route for mesoporous metal oxides preparation. [•] CuCeO x catalysts with high surface area and homogeneous mesostructure. [•] Catalysts combined promoted reducibility and surface oxygen concentration. [•] Mesostructured metal oxides with superior low-temperature catalytic efficiency. [•] Catalysts possess remarkable enhanced reaction rate and selectivity. [Copyright &y& Elsevier]

Abstract: Catalytic oxidation is a widely used pollution control technology for removing volatile organic compounds. Pd–Ce/ZSM-5 catalysts with different Ce contents were prepared by a co-impregnation method, and their catalytic performance was investigated for the oxidation of methyl ethyl ketone (MEK). The by-products of the reaction were monitored using gas chromatography and collected in thermal desorption tubes, which were further analyzed by gas chromatography/mass spectrometry. The PdCe9.6/ZSM-5 catalyst displayed the highest catalytic efficiency, as a consequence of a higher amount of strong acid sites and a superior PdO-Pd redox cycle in the presence of a CeO2 additive. The introduction of CeO2 enriched the by-product species. The formation mechanisms and oxidation routes of typical by-products, such as methyl acetate, 1-penten-3-one and 3-buten-2-one, 3-methyl, during MEK oxidation over Pd–Ce/ZSM-5 catalysts was also analyzed. CH3* species that formed on the catalyst were identified as reaction intermediaries. Trace amounts of acetic acid and methyl vinyl ketone were also detected and were further oxidized to methyl acetate, 1-penten-3-one and 3-buten-2-one, 3-methyl. [Copyright &y& Elsevier]

Developing economical and robust catalysts for the highly selective and stable destruction of chlorinated volatile organic compounds (CVOCs) is a great challenge. Here, hollow nanosphere-like VOx/CeO2 catalysts with different V/Ce molar ratios were fabricated and adopted for the destruction of1,2–dichloroethane (1,2–DCE). The V0.05Ce catalyst possessed superior catalytic activity, reaction selectivity, and chlorine resistance owing to a large number of oxygen vacancies, excellent low-temperature redox ability, and chemically adsorbed oxygen (O− and O2−) species mobility. Typical chlorinated byproducts (CHCl3, CCl4, C2HCl3, and C2H3Cl3) derived from the cleavage of C–Cl and C–C bonds of 1,2–DCE were detected, which could be effectively inhibited by the abundant acid sites and the strong interactions of VOx species with CeO2. The presence of water vapor benefited the activation and deep destruction of 1,2–DCE over V0.05Ce owing to the efficient removal of Cl species from the catalyst surface. [ABSTRACT FROM AUTHOR]

[Display omitted] • CuO x /MnO 2 catalysts with different crystal phases of MnO 2 were synthesized. • CuO x / α-MnO 2 catalyst showed excellent catalytic activity in NO reduction and CO oxidation. • The presence of CO enhanced the NH 3 -SCR catalytic activity of catalyst. • Mechanism model for NO reduction and CO oxidation was proposed. NO and CO are two primary pollutants in the sintering flue gas emission, posing significant challenges for the treatment. Under oxygen-enriched conditions, CO was easily oxidized to CO 2 before participating in CO-SCR reaction as a reducing agent. Consequently, NH 3 -SCR technology coupled with CO oxidation reaction is a promising approach for simultaneous NO and CO removal. In this study, a series of bifunctional CuO x /MnO 2 catalysts were synthesized using a combine of hydrothermal and wet impregnation methods, and their catalytic performance for simultaneous removal of NO and CO was assessed. CuO x /α-MnO 2 catalyst displayed outstanding catalytic activity for both NO and CO, achieving over 80 % NO removal efficiency and 96 % CO conversion rate at 150 °C, while CuO x /β-MnO 2 catalyst exhibited poor catalytic activity in the entire temperature range. Moreover, the interplay between the NH 3 -SCR and CO catalytic oxidation reactions was also explored. XPS results revealed that the concentration of Mn4+ and Cu+ species significantly influenced the catalytic activity of the catalysts for the simultaneous removal of NO and CO. Particularly, the presence of Mn4+ species promoted "fast SCR" reaction, whereas Cu+ species demonstrated higher reactivity for both NO reduction and CO oxidation. In situ DRIFTS analysis of transient reactions revealed that the L-H mechanism was followed over CuO x /α-MnO 2 catalyst in the NH 3 -SCR reaction, while both the M-K and L-H mechanisms were observed in CO catalytic oxidation reaction. [ABSTRACT FROM AUTHOR]

[Display omitted] • Mn-decorated ZIF-67 derived catalyst is synthesized by MOF-template method. • The interface interaction enhances the mineralization rate of the catalyst. • MnCoO x -M existed the best catalytic activity, stability, and water resistance. • The introduction of H 2 O obviously inhibited the generation of organic by-products. Herein, a Mn cations highly dispersed and bimetallic interfacial interaction strengthen catalyst, MnCoO x , via combinations of MOF-templated method, Mn cation doping has been constructed for the chlorobenzene (CB) oxidation. As a result, MnCoO x -M possessed the best chlorobenzene degradation capacity and stability than those of similar bimetallic compounds prepared by co-precipitation method and single-phase oxide. Notably, this superior catalyst obtained a high mineralization efficiency with inhibition effect of the CO generation. The excellent performance of MnCoO x -M can be conducted to the good dispersion of the metal cations as well as a stronger Mn-Co interaction, which are further induced the excellent redox properties of the catalyst. Besides, the humidity tolerance experiments showed that a certain H 2 O participation can significantly inhibit the generation of some types of organic by-products, especially chlorinated organic compounds. Mechanistic studies showed that chlorobenzene dissociated on the surface of MnCoO x -M to form benzoquinone, phenolates, maleates, etc., which were finally oxidized to inorganic products. [ABSTRACT FROM AUTHOR]

Anatase titania hollow spheres (THS) composed of nanoplates with dominant {001} facets and nanoparticles without dominant {001} facets were successfully prepared, respectively. The physicochemical properties of the two kinds of THS were characterized systematically, and their photocatalytic performances for the mineralization of ciprofloxacin, one of PPCPs, were compared in detail. The results showed that the former presented higher photocatalytic performance due to {001} facet exposure and better crystallinity. [ABSTRACT FROM AUTHOR]

[Display omitted] Fabricating of economical transitional metal oxide-based materials with satisfied low-temperature catalytic performance and application perspective is still a challenge in deep degradation of VOCs. Here, Mn-Cu bimetallic oxides were facilely prepared by one-step hydrothermal-redox method, which displayed much higher catalytic activity in toluene oxidation than those synthesized by hydrolysis-driven redox-precipitation or co-precipitation approach. It is shown that the lattice defect and oxygen vacancy concentration over prepared materials can be tuned by controlling Cu/Mn molar ratio. Amongst, spinel structured MnCu 0.5 exhibited the highest catalytic activity, superior durability and water resistance in toluene total oxidation owing to abundant surface adsorbed oxygen species, excellent low-temperature reducibility, and high amounts of Cu+ and Mn3+. In detail, the reaction rate of MnCu 0.5 was over 9.0 times higher than that of MnCu 0.75 , MnCu 0.75 -P and MnCu 0.75 -H 2 O 2 at relative low temperature of 210 °C. The cyclic redox process with easier oxygen species mobility played a key role in the catalytic oxidation of toluene. Typical reaction intermediates as benzyl alcohol, benzaldehyde, benzene, phenol, and benzoquinone could be detected by PTR-MS, which further decomposed to acetone, ethanol, ketone, acetic acid, methanol, formaldehyde and acetaldehyde species by ring opening before total mineralization. [ABSTRACT FROM AUTHOR]

We investigated the industrially important PtSn/Al 2 O 3 catalysts prepared with uniform particle sizes (∼ 1 nm) and varied compositions using molecular complexes of Pt(II) and Sn(II). Our best catalyst, with a Sn:Pt ratio of around 2, exhibited a high initial propylene productivity of about 1.1 mol C 3 H 6 (g catalyst)−1 h−1. Elaborate electron microscopy studies revealed significant compositional variations in the catalyst, highlighting the practical challenges in achieving or confirming the theoretically predicted optimum Sn:Pt ratio. It is also found that the catalytic activities correlate well with the Pt dispersion, suggesting the structure-insensitive nature of the dehydrogenation reaction applies to these ultrasmall Pt-Sn nanoparticles. The presence of Pt-rich particles in the catalysts did not produce noticeable degradations in the reaction selectivity, indicating a wide composition range for Pt-Sn nanoparticles to be effective at the 1 nm size range. These findings emphasize the importance of detailed analysis of compositional distributions for understanding and optimizing nanoalloys. [Display omitted] • PtSn/Al 2 O 3 catalysts with uniform particle sizes and varied compositions are prepared using Pt(II)-Sn(II) complexes. • High initial C 3 H 6 productivity of 1.1 mol C 3 H 6 g catalyst -1 h-1 is achieved by our best catalyst with Sn:Pt ratio of around 2. • Significant compositional variations in the catalysts are revealed through comprehensive electron microscopy studies. • Structure-insensitive nature of propane dehydrogenation reaction applies to these ultrasmall Pt-Sn nanoparticles. [ABSTRACT FROM AUTHOR]

• Porous MnCoNiO x trimetallic spinel-type oxide (MCNO) catalyst was prepared. • MCNO material possesses large specific surface area and superior reducibility. • Non-thermal plasma-MCNO system has excellent toluene decomposition efficiency. • Catalyst combined with plasma enhances CO 2 selectivity and O 3 decomposition rate. A novel strategy for removal of toluene by non-thermal plasma (NTP) coupled with metal-organic frameworks (MOFs) derived catalyst was proposed in this work. The MOF-derived porous trimetallic oxide catalyst (MnCoNiO x , MCNO) was prepared by simple pyrolysis of a MOF-74(Mn-Co-Ni) precursor. We found that the MCNO material can well synergy with NTP in total decomposition of toluene owing to its high specific surface area, regular porous structure and excellent reducibility, which endow superior catalytic activity and CO 2 selectivity of NTP-MCNO system compared to that of NTP-MnO x , NTP-CoO x and NTP-NiO x. For instance, the toluene degradation efficiency can reach up to 75.7% in NTP-MCNO system with a low specific input energy of 101 J/L, much higher than that of NTP-MnO x (59.3%), NTP-CoO x (70.9%), NTP-NiO x (65.0%) and NTP alone (42.9%). Moreover, the formed ozone (O 3) can be well-controlled by the NTP-MCNO system due to the spinel-type oxides (MCNO) derived from MOF could generate more open-formwork structure and improve the mobility of oxygen. The results of this work would shed light on rational design and preparation of spinel-type oxides for oxidation applications, which provides guidance for further improvement of plasma-catalysis system. [ABSTRACT FROM AUTHOR]

• Spherical-like Pd-based catalysts were rationally prepared by different protocols. • High Pd dispersion favors the catalytic activity in n -butylamine combustion. • High porosity of catalysts is beneficial for NO x formation control. • Pd/S-2 IS prepared by in situ synthesis method shows the best catalytic performance. • The n -butylamine destruction mechanism was proposed by in situ DRIFTS. Two types spherical-like SiO 2 with different specific surface area (SSA) and porosity were synthesized and used as support for Pd catalysts, which were prepared by various protocols (in situ synthesis (IS, Pd/S-1 IS , and Pd/S-2 IS), wet impregnation (WI, Pd/S-1 WI , and Pd/S-2 WI), and grafting (GA, Pd/S-1 GA , and Pd/S-2 GA)) and adopted in n -butylamine combustion. Results suggest that Pd dispersion is positive correlation with support SSA and GA method is the most favorable approach to obtain highly dispersed Pd active sites. Pd/S-1 IS , Pd/S-1 WI , and Pd/S-1 GA catalysts with small SSA show inferior activity and higher NO x yield than those of Pd/S-2 IS , Pd/S-2 WI , and Pd/S-2 GA with large SSA, irrelevant with the preparation methods. Amongst, Pd/S-2 GA possesses the smallest Pd average diameter (ca. 1.72 nm) and highest activity with 90% of n -butylamine destructed at 234 °C; however, the yield of NO x over Pd/S-2 GA is much higher than the other catalysts (except Pd/S-1 GA) as the GA approach provides high concentration of active sites and the preparation procedure sacrifices the SSA and porosity of supports to some extent. In situ DRIFTS results reveal that the developed porosity of catalyst promotes nitrogen-containing by-products (NH x) transfer and diffusion and avoids their further oxidizing to NO x. The activity of samples prepared by the WI process is lower than that prepared by the IS or GA method due to limited active sites. Comparatively, the Pd/S-2 IS prepared by the IS method has relative high activity (T 90 of 240 °C) and low NO x yield (0.99% at T 90) in n -butylamine oxidation among all materials, exhibiting an attractive prospective in nitrogen-containing VOC environment-friendly elimination. [ABSTRACT FROM AUTHOR]

The efficient catalytic oxidation of nitrogen-containing volatile organic compounds remains a big challenge due to unmanaged production of harmful byproducts. Herein, a series of Cu-Mn modified hierarchical SAPO-34 zeolite catalysts with different pore structures were synthesized for n-butylamine oxidation. The physicochemical properties and catalytic performance of catalysts were investigated and analyzed in detail. Among them, CuMn/S-1 shows the highest activity (T 90 = 279 °C, GHSV = 12,000 h−1), which is attributed to its higher porosity, higher surface acidity and superior reducibility. Meanwhile, it is found that the hierarchical structure and mesopore play an important role in improvement of N 2 selectivity. Meanwhile, CuMn/S-1 also exhibits high stability and water resistance. The catalytic mechanism of n-butylamine on CuMn/SAPO-34 was investigated by in situ DRIFTS, showing that propanol, methanol and acetate are the main intermediates. [Display omitted] • A series of Cu-Mn modified hierarchical SAPO-34 zeolite catalysts were prepared. • CuMn/S-1 shows the excellent n-butylamine oxidation activity and high N 2 selectivity. • Acidity and reducibility are the key factors determining catalytic activity in low/high temperature, respectively. • The hierarchical structure and acidity have effects on N 2 selectivity. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Thermally deactivated Fe 2 (SO 4) 3 /TiO 2 (FeTi-T) was obtained by thermal treatment. • Fe 2 (SO 4) 3 decomposition causes Brønsted acid sites loss and catalyst deactivation. • The in situ recovery of FeTi-T is achieved by SO 2 in the flue gas. • Fe 2 (SO 4) 3 is formed by SO 2 /O 2 and Fe 2 O 3 under NH 3 -SCR reaction conditions. Abstract Due to high catalytic activity and excellent resistance to SO 2 and H 2 O, sulfate materials are considered to be promising vanadium-free catalysts for selective catalytic reduction of NO x with NH 3 (NH 3 -SCR). Despite this, investigations about thermal stability of sulfate SCR catalysts are limited, which is surprising given that sulfates are typically susceptible to thermal decomposition. In this work, the thermal stability of Fe 2 (SO 4) 3 /TiO 2 catalysts was investigated. It was determined that the thermal decomposition of Fe 2 (SO 4) 3 resulted in NO x conversion decreased from 90% to 60% at 350 °C. Interestingly however, the introduction of SO 2 into the gas stream was found to reverse the effects of the thermal deactivation and the NO x conversion of 90% (350 °C) was once again observed. Extensive characterization of each catalyst sample and density functional theory (DFT) calculations were subsequently conducted. The reduction in catalytic activity after the thermal treatment was attributed to the transformation of Fe 2 (SO 4) 3 to α-Fe 2 O 3 , which reduced the quantity of Brønsted acid sites on the catalyst. The presence of SO 2 in the gas stream was found to reverse this phase transformation which ultimately led to the recovery of Brønsted acid sites. DFT calculations indicated that SO 2 adsorbed selectively on Fe atoms of the thermal deactivated catalysts and S-Fe bond should mainly be formed by electrons from p orbitals of S and Fe atoms. Then NH 3 could be adsorbed on the surface by N-S bond with SO 2. The recoverable property of this catalyst provides a promising outlook for the commercial application, especially given that industrial flue gas streams regularly contain SO 2. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Facet-dependent de-NO x based on α-Mn 2 O 3 was investigated for the first time. • The new active sites on (0 0 1) facets induced by charge redistribution are revealed first. • The experimental results and DFT calculated results are well verified by each other. • New insights into the understanding of crystal-facet-dependent reactivity are provided. Abstract Crystal facets usually play an important role in the catalytic activity of inorganic single crystals. In this work, two α-Mn 2 O 3 single crystals with an octahedron (exposed with (1 1 1) facet) and a truncated octahedron (exposed with both (1 1 1) and (0 0 1) facets) were successfully prepared by a simple solvent-thermal reaction, and their catalytic activities were evaluated by the selective catalytic reduction (SCR) of NO x with NH 3. The results show that the catalytic performance of the α-Mn 2 O 3 single crystal with a truncated octahedron was enhanced in comparison with the α-Mn 2 O 3 single crystal with an octahedron by the exposure of a small fraction of (0 0 1) facets. This can be attributed to the new active sites created by charge redistribution on the surface of the (0 0 1) facets, which provides more adsorption sites, facilitating the further adsorption and reaction of NH 3 and NO molecules, and thereby enhancing the catalytic performance. This work should provide new insight into the understanding of crystal-facet-dependent reactivity and important guides for the design and preparation of SCR catalysts with high activity. [ABSTRACT FROM AUTHOR]

[Display omitted] • A chelating agent-assistant strategy was adopted to fabricate γ-MnO 2 catalyst. • Chelating agent weakened the Mn-O bond and boost oxygen-activating ability. • γ-MnO 2 modified by citric acid had high low-temperature NO oxidation activity. • Oxygen vacancy reduced vacancy formation energy and promoted O 2 dissociation. To date, the exploitation of non-noble materials of high-efficiency and low-temperature conversion of NO to NO 2 still existed as a challenging task due to high cost of current Pt-based commercial catalysts. Herein, we employed a chelating agent-assistant strategy to regulate the content of oxygen vacancy over γ-MnO 2 catalysts, which were further used for NO oxidation. Benefiting from the structure-directing effect of tartaric acid, the resultant locus-shaped γ-MnO 2 catalyst with abundant oxygen vacancies showed a remarkable low-temperature catalytic activity (T 50 and T 92 of 127 and 225 °C; respectively), which was superior to unmodified γ-MnO 2 sample (T 50 at 189 °C) and those recently reported good-performing NO oxidation catalysts. An array of characterization results revealed that an extended capping by means of chelating agents could effectively weaken the Mn O bond strength and promote the formation of oxygen vacancy (OVs), thus tremendously increase the amount of surface-active oxygen species. Moreover, theoretical calculation demonstrated that an enriched OVs concentration could enhance the reactivity of surface lattice oxygen by reducing the formation energy of OVs, further accelerating reaction rate of the adsorption/activation of O 2 molecules and thus bringing about an outstanding low-temperature catalytic activity. This study highlighted the potential of chelating agents in the design of high-efficient catalysts for environmental remediation and beyond. [ABSTRACT FROM AUTHOR]

A series of MFI zeolites with different Si/Al ratios were pretreated by a basic solution and their catalytic activity was evaluated in N 2 O decomposition after iron exchange. The performance of Fe-ZSM-5 catalysts could be improved by alkaline pretreatment. Among these samples, the activity curve of Fe-Z5-250-S sample could move to low temperature by >100 °C with a good preservation of hydrothermal stability. It is found that with the meso-microporous hybrid structure, the content of iron as active metal is significantly increased. Additionally, well preservation of the chemical environment around the tetrahedral aluminum and the site accessibility probably may be the other important factors to influence the catalytic activity. [ABSTRACT FROM AUTHOR]

Mn3O4, FeMnO x , and FeO x catalysts synthesized via a solvothermal method were employed for catalytic oxidation of methyl-ethyl-ketone (MEK) at low temperature. Mn3O4 with sphere-like morphology exhibited the highest activity for MEK oxidation, over which MEK was completely oxidized to CO2 at 200 °C, and this result can be comparable to typical noble metal loaded catalysts. The activation energy of MEK over Mn3O4 (30.8 kJ/mol) was much lower than that of FeMnO x (41.5 kJ/mol) and FeO x (47.8 kJ/mol). The dominant planes, surface manganese species ratio, surface-absorbed oxygen, and redox capability played important roles in the catalytic activities of catalysts, while no significant correlation was found between specific surface area and MEK removal efficiency. Mn3O4 showed the highest activity, accounting for abundant oxygen vacancies, low content of surface Mn4+ and strong reducibility. The oxidation of MEK to CO2 via an intermediate of diacetyl is a reaction pathway on Mn3O4 catalyst. Due to high efficiency and low cost, sphere-shaped Mn3O4 is a promising catalyst for VOCs abatement. [ABSTRACT FROM AUTHOR]

Effects of propane/methane ratios on NO x reduction by mixtures of methane and propane over In/H-BEA catalyst were investigated at temperatures ranging from 250 to 550 °C. The higher catalytic activity of In/H-BEA was exhibited for CH 4 -SCR at high temperatures above 450 °C, while the higher NO x conversion was achieved in C 3 H 8 -SCR at below 425 °C. A broadened temperature window and enhanced CO 2 selectivity were achieved by combining of methane and propane as the co-reductant. The mixtures with propane/methane of 1/2 showed the most superior T 50 (325 °C) and T 90 (500 °C) temperatures for NO x reduction over In/H-BEA catalyst. For the promotion mechanism of propane on NO reduction by methane at low temperature, the formation of carbonaceous species (e.g. R-COOH) were enhanced by the activation of C 3 H 8 on Brønsted acid sites at low temperature, and further promoted the generation of NCO species, which was a crucial determining step for NO reduction. [ABSTRACT FROM AUTHOR]

The deposition of K can lead to deactivationof commercial V2O5–WO3/TiO2selectivecatalytic reduction (SCR) catalyst while the presence of SO2largely increases the activity of K-poisoned catalyst. For revealingthe mechanism of the SO2effect on the SCR reaction, theK-poisoned catalyst was prepared by impregnation of KNO3solution and in situ diffuse reflectance infrared Fourier transformspectroscopy (DRIFTS) was carried out on the fresh and K-poisonedcatalyst. The results showed that the adsorption of SO2in the presence of O2was different between fresh andK-poisoned catalyst. The tridentate sulfate was formed with titaniumin the fresh catalyst. While on the K-poisoned catalyst, the bidentatesulfate was likely formed with vanadium, which increased the numberof Brønsted acid sites and the activity of the catalyst significantly. [ABSTRACT FROM AUTHOR]

[Display omitted] • Mn-Cu bimetallic catalysts were facilely prepared by one-step hydrothermal-redox method. • Hydrothermal-redox was superior to other preparation methods for Mn-Cu catalysts. • MnCu spinel type catalyst exhibited excellent low-temperature catalytic performance. • PTR-MS results revealed the reaction routes of toluene oxidation over MnCu catalyst. Developing facile preparation method to obtain the satisfied low-temperature catalytic performance of transitional metal oxide-based materials is still a challenge in deep degradation of VOCs. Here, a series of Mn-Cu bimetallic oxide catalysts were prepared by one-step hydrothermal-redox method for catalytic total oxidation of toluene. The CH 3 COOH concentration, Cu/Mn molar ratio and calcination temperature greatly affected the crystal structure, micromorphology and catalytic performance. Amongst, MnCu spinel structured catalyst exhibited excellent low-temperature catalytic activity, superior durability and water resistance in toluene total oxidation owing to its abundant surface adsorbed oxygen species, higher amount of Cu+ and Mn3+ and excellent low-temperature reducibility. The reaction rate of MnCu was 7.0 times higher than that of MnCu 0.5 at 210 °C. The cyclic redox process with enough oxygen vacancy played a vital role in toluene oxidation. The deep oxidation of benzene was the key step in the toluene oxidation. Proton transfer reaction-mass spectrometry (PTR-MS) results revealed the reaction intermediates including benzaldehyde, benzene and phenol, which further decomposed to acetone, ethanol, acetic acid, ketone and acetaldehyde by ring opening before total mineralization. Therefore, PTR-MS provided a facile method to investigate the reaction mechanism of toluene oxidation. [ABSTRACT FROM AUTHOR]

• 3DOM γ-MnO 2 /LaMnO 3.15 (Mn/3DLM) has high activity and chlorine resistance. • The formation of high-risk byproducts over Mn/3DLM is remarkably inhibited. • High surface area and connected pores of 3DOM catalysts are favorable to diffusion. • Chlorobenzene destruction mechanism over prepared catalysts was proposed. Catalytic activity of perovskite oxides as LaMnO 3+δ is greatly limited by their low surface area and deficient active site density though they are thought to be one category of desired candidates for noble metal-based catalysts. Here, a robust three dimensional ordered macroporous (3DOM) γ-MnO 2 /LaMnO 3.15 (Mn/3DLM) was in situ fabricated by the strategy of selectively dealloyed surface La cations. Mn/3DLM displayed excellent activity with 90% of chlorobenzene destructed at 207 °C (apparent activation energy of 45.4 kJ/mol), obviously lower than those of γ-MnO 2 (244 °C; 51.9 kJ/mol) and bulk LaMnO 3.15 (311 °C; 70.2 kJ/mol) owing to large surface area, excellent reducibility, and improved surface active oxygen concentration. Nucleophilic substitution was the main process for active oxygen attacking, while electrophilic substitution mainly contributed to chlorinated byproducts formation. Remarkably, reaction byproducts as phenol, o -dichlorobenzene, trichloroethylene, and bichloroethylene over Mn/3DLM can be efficiently inhibited during the long-term operations via weakened the electrophilic substitution effect. [ABSTRACT FROM AUTHOR]