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Formaldehyde (HCHO) is a common indoor air pollutant. Due to its proven carcinogenicity, reducing indoor HCHO levels is a significant issue. In this study, a composite material consisting of zinc manganese oxide and BiVO4 was used as a photocatalyst for HCHO degradation. ZnMn2O4‐BiVO4 has efficient photocatalytic performance, wide application areas, high stability, and low‐cost advantages, making the substance a potentially useful photocatalyst that can be applied in fields such as energy conversion and environmental protection. BiVO4 was prepared by a hydrothermal method. It was further compounded with zinc manganese oxide to form composite as catalysts of different wt % ratios for photodegradation of HCHO using a fluorescent lamp as light source. The samples were characterized by using XRD, UV‐visible spectrometer, TEM, SEM, and photoluminescence spectrometry. The experimental data showed that 5.0 wt % zinc manganese oxide‐BiVO4 as catalyst had the highest HCHO degradation rate. The release of carbon dioxide and water increased the irradiation time. The degradation rate of HCHO was higher than that achieved with commercially available titanium oxide. The highest HCHO degradation rate was 66 % within 4 h. [ABSTRACT FROM AUTHOR]

The practical application of room‐temperature sodium‐sulfur (RT Na–S) batteries is blocked by the notorious shuttle effect of sodium polysulfides (NaPSs) and sluggish refox reaction kinetics. Single‐atom catalysts (SACs) have been widely studied for boosting the energy storage performance of RT Na‐S batteries. Nevertheless, the catalytic centers of SACs reported so far have focused mainly on symmetrical metal–N4 structures, which offer weak bonding affinity toward polar NaPSs, leading to detrimental shuttle effect and sluggish sulfur conversion kinetics. Herein, a novel asymmetrical Mn–N2 structure is implanted into nitrogen‐doped carbon nanofibers (Mn‐N2/CNs) through thermal NH3 etching of a symmetrical Mn–N2O2 structure. The Mn–N2 structure promotes the bonding affinity and catalytic conversion of NaPSs due to the strengthened d‐p orbital‐hybridization between the d orbital of Mn in the Mn–N2 structure and the p orbital of S in NaPSs. Consequently, Mn‐N2/CNs@S achieves a high capacity of 458 mAh g−1 at 3.0 C with a capacity decay of 0.23% over 2300 cycles. This work offers a promising pathway for regulating the coordination number of SACs with strengthened d‐p orbital‐hybridization for high‐performance RT Na–S batteries. [ABSTRACT FROM AUTHOR]

Aliovalent substitution reduces the oxygen vacancy formation energy and generates more oxygen vacancies to facilitate the catalytic reaction. [Display omitted] 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 (T 90 = 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. [ABSTRACT FROM AUTHOR]

Herein, a series of pincer–Mn complexes based on bis(imino)pyridine ligands of the type R2NNN (R = tBu, iPr, Cy and Ph) were synthesized and characterized using various spectroscopic techniques. SCXRD studies revealed a trigonal bipyramidal geometry around the metal center in all the complexes. EPR spectroscopy confirmed the presence of high-spin Mn(II) centers with the consistent observation of sextets in EPR spectra. Additionally, solution magnetic moment measurement exhibited values ranging from 5.8 to 6.2 BM for all the complexes, which are in accordance with the theoretical value of 5.92 BM. HRMS analysis complemented structural characterization, showing fragments corresponding to various solvent adducts and derivatives of the complexes. Subsequently, the synthesized complexes were investigated for their catalytic activity in the transfer dehydrogenation of glycerol to lactic acid in the presence of acetone. Among the considered complexes, the catalyst Ph2NNNMnCl2 was found to be highly efficient. Remarkably, a yield of 92% LA was observed with >99% selectivity at 0.5 mol% loading of Ph2NNNMnCl2 in the presence of 1 equivalent of NaOH at 140 °C in 24 h, surpassing the yield obtained from its precursor MnCl2·4H2O, where a yield of 72% LA was observed with 96% selectivity under similar reaction conditions. This catalytic system was further investigated with a range of acceptors, and good to moderate yields were observed in most cases. Moreover, several control experiments, including reaction with PPh3, CS2 and Hg, highlighted the major involvement of molecular species in the reaction medium. Deuterium labelling studies indicated the involvement of C–H bond activation in the catalytic cycle but not in the rate-determining step (RDS), with a secondary kinetic isotope effect (KIE) of 1.25. [ABSTRACT FROM AUTHOR]

Herein, we report an efficient and sustainable manganese‐catalyzed α‐C−H bond alkylation methodology to synthesize branched sulfones via a hydrogen borrowing pathway. The air‐stable and phosphine‐free Mn‐catalyst, (NNN)Mn(II)Cl2 was synthesized by using an earth‐abundant, commercially available, and inexpensive precursor MnCl2.4H2O, and a stable NNN pincer i. e. [N‐((benzimidazole‐2‐yl)methyl)quinoline‐8‐amine] ligand system. Taking benzyl phenyl sulfones as substrates, and benzyl alcohol derivatives as alkylating agents, a range of branched sulfones were synthesized in 40–82 % isolated yields using (NNN)Mn(II)Cl2 complex as the catalyst under open‐air conditions. Control experiments and deuterium incorporation studies have also been conducted to investigate the possible reaction mechanism and to provide evidence for the hydrogen borrowing pathway. [ABSTRACT FROM AUTHOR]

Mn‐catalyzed hydroarylation polyaddition of 1‐(2‐pyrimidinyl)pyrrole (1a) with aromatic diynes is investigated. The use of commercially available MnBr(CO)5 as a precatalyst under the optimized reaction conditions resulted in a site‐ and regioselective hydroarylation polyaddition, affording the corresponding poly(arylenevinylene)s (PAVs) with excellent vinylene selectivity. The reaction protocol eliminates the production of stoichiometric amounts of byproducts from the monomers. The nonstoichiometric polyaddition of an excess amount of 1a with aromatic diynes is also demonstrated. The 2‐pyrimidinyl substituent promoted the intramolecular transfer of the Mn catalyst walking through the 1a moiety. [ABSTRACT FROM AUTHOR]

The tert‐butyl group is a common aliphatic motif extensively employed to implement steric congestion and conformational rigidity in organic and organometallic molecules. Because of the combination of a high bond dissociation energy (~100 kcal mol−1) and limited accessibility, in the absence of directing groups, neither radical nor organometallic approaches are effective for the chemical modification of tert‐butyl C−H bonds. Herein we overcome these limits by employing a highly electrophilic manganese catalyst, [Mn(CF3bpeb)(OTf)2], that operates in the strong hydrogen bond donor solvent nonafluoro‐tert‐butyl alcohol (NFTBA) and catalytically activates hydrogen peroxide to generate a powerful manganese‐oxo species that effectively oxidizes tert‐butyl C−H bonds. Leveraging on the interplay of steric, electronic, medium and torsional effects, site‐selective and product chemoselective hydroxylation of the tert‐butyl group is accomplished with broad reaction scope, delivering primary alcohols as largely dominant products in preparative yields. Late‐stage hydroxylation at tert‐butyl sites is demonstrated on 6 densely functionalized molecules of pharmaceutical interest. This work uncovers a novel disconnection approach, harnessing tert‐butyl as a potential functional group in strategic synthetic planning for complex molecular architectures. [ABSTRACT FROM AUTHOR]

The current study involved the preparation of a number of MnOx/Sep catalysts using the impregnation (MnOx/Sep-I), hydrothermal (MnOx/Sep-H), and precipitation (MnOx/Sep-P) methods. The MnOx/Sep catalysts that were produced were examined for their ability to catalytically oxidize formaldehyde (HCHO). Through the use of several technologies, including N2 adsorption–desorption, XRD, FTIR, TEM, H2-TPR, O2-TPD, CO2-TPD, and XPS, the function of MnOx in HCHO elimination was examined. The MnOx/Sep-H combination was shown to have superior catalytic activities, outstanding cycle stability, and long-term activity. It was also able to perform complete HCHO conversion at 85 °C with a high GHSV of 6000 mL/(g·h) and 50% humidity. Large specific surface area and pore size, a widely dispersed active component, a high percentage of Mn3+ species, and lattice oxygen concentration all suggested a potential reaction route for HCHO oxidation. This research produced a low-cost, highly effective catalyst for HCHO purification in indoor or industrial air environments. [ABSTRACT FROM AUTHOR]

An unsymmetrical Mn(II) Schiff base complex was attached to MCM-41. The synthesized catalyst was characterized by powder X-ray diffraction (XRD), nitrogen adsorption/desorption isotherms, inductivity coupled plasma (ICP), Fourier Transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The immobilized Schiff base complex was an efficient catalyst for oxidation of sulfides with hydrogen peroxide. In addition, this green oxidation system was used to oxidize various sulfides and the results showed that sulfoxides were the major products. Finally, the reuse of the catalyst was also investigated [ABSTRACT FROM AUTHOR]

Defect manipulation in metal oxide is of great importance in boosting catalytic performance for propane oxidation. Herein, a selective atom removal strategy was developed to construct a defective manganese oxide catalyst, which involved the partial etching of a Mg dopant in MnOx. The resulting MgMnOx-H catalysts exhibited superior low-temperature catalytic activity (T50 = 185 °C, T90 = 226 °C) with a propane conversion rate of 0.29 μmol·gcat.−1·h−1 for the propane oxidation reaction, which is 4.8 times that of pristine MnOx. Meanwhile, a robust hydrothermal stability was guaranteed at 250 °C for 30 h of reaction time. The comprehensive experimental characterizations revealed that the catalytic performance improvement was closely related to the defective structures including the abundant (metal and oxygen) vacancies, distorted crystals, valence imbalance, etc., which prominently weakened the Mn-O bond and stimulated the mobility of surface lattice oxygen, leading to the elevation in the intrinsic oxidation activity. This work exemplifies the significance of defect engineering for the promotion of the oxidation ability of metal oxide, which will be valuable for the further development of efficient non-noble metal catalysts for propane oxidation. [ABSTRACT FROM AUTHOR]

The first example of manganese-catalyzed asymmetric transfer hydrogenation of N-heteroaromatics in water is reported. This ATH reaction proceeds smoothly without the need for inert atmosphere protection in the presence of a water-stable manganese catalyst, which bears an easily available aminobenzimidazole ligand. Ammonia borane, regarded as a green, cheap and high atom economical hydrogen source, was applied. Various quinolines are transformed into the desired products in high yields and up to 99% enantiomeric excess (ee). The utility of the current protocol was demonstrated by applying it in the gram-scale total synthesis of the Hancock alkaloid (−)-cuspareine with 96% overall yield. [ABSTRACT FROM AUTHOR]

The article outlines the possibility of achieving a comprehensive solution to environmental problems, specifically by neutralizing toxic carbon monoxide and treating wastewater generated during metallurgical production. The use of spent iron sulfate-containing etching solutions allows the creation of effective and affordable manganese-ferrite catalyst systems on a zeolite carrier. The novelty of the study is the use of «green» chemicals - ferrates that include iron (VI) and have great potential in environmentally friendly water treatment technologies. The use of potassium ferrate reduces the need for an alkaline reagent to produce a ferritic material. Confirmation of the composition of the main elements of catalysts was carried out using qualitative X-ray phase and micro-X-ray spectral analysis. The use of an innovative manganese-ferrite catalyst to neutralize carbon monoxide obtained using potassium ferrate provides a successful solution to the problem of toxic gas emission in electrode manufacturing technology and creates pathways for the transition to a circular economy. The cost-effectiveness and environmental friendliness of using the proposed catalyst on a zeolites carrier in a reactor located in the fire channels of the chambers of the Riedhammer multi-chamber furnaces for burning electrode blanks are demonstrated. The preparation of a catalyst from spent sorbents for purifying manganese-containing natural water emphasizes its sustainable nature and contribution to solving environmental problems in the context of production processes. The safety of burial or storage in landfills of ferritic sludge sediments as an analog of magnetite distributed in the earth's crust further emphasizes the importance of the proposed method. [ABSTRACT FROM AUTHOR]

The efficient and rapid removal of volatile organic compounds (VOCs) holds significant importance for ensuring food quality and human health, particularly within the low-temperature confined spaces in refrigerators. However, achieving effective VOCs degradation under such conditions poses challenges in terms of activating inert bonds and facilitating mass transfer. In this study, we propose a novel solution by designing a cleaner module that incorporates 1.07% single Fe atom-anchored manganese dioxide catalysts (FeSAs-MnO2). The combination of single Fe atoms and defect-rich MnO2 substrate efficiently activates molecular oxygen, leading to enhanced generation of highly reactive oxygen species (ROS). Non-thermal plasma (NTP) and circulating fan are introduced to facilitate the regeneration of catalytic activity and improve mass transfer. The FeSAs-MnO2 cleaner module demonstrates exceptional performance in trimethylamine (TMA) removal, achieving a conversion efficiency of 98.9% for 9 ppm within just 9 min. Furthermore, accelerated aging tests predict an extended service life of up to 45 years for the FeSAs-MnO2 cleaner module, surpassing the expected lifespan of refrigerators significantly. [ABSTRACT FROM AUTHOR]

Manganese catalysts that activate hydrogen peroxide carry out several different hydrocarbon oxidation reactions with high stereoselectivity. The commonly proposed mechanism for these reactions involves a key manganese(III)-hydroperoxo intermediate, which decays via O–O bond heterolysis to generate a Mn(V)–oxo species that institutes substrate oxidation. Due to the scarcity of characterized MnIII–hydroperoxo complexes, MnIII–alkylperoxo complexes are employed to understand factors that affect the mechanism of the O–O cleavage. Herein, we report a series of novel complexes, including two room-temperature-stable MnIII–alkylperoxo species, supported by a new amide-containing pentadentate ligand (6Medpaq5NO2). We use a combination of spectroscopic methods and density functional theory computations to probe the effects of the electronic changes in the ligand sphere trans to the hydroxo and alkylperoxo units to thermal stability and reactivity. The structural characterizations for both MnII(OTf)(6Medpaq5NO2) and [MnIII(OH)(6Medpaq5NO2)](OTf) were obtained via single-crystal X-ray crystallography. A perturbation to the ligand sphere allowed for a marked increase in reactivity towards an organic substrate, a modest change in the distribution of the O–O cleavage products from homolytic and heterolytic pathways, and little change in thermal stability. [ABSTRACT FROM AUTHOR]

A vacancy-rich Co/MnO@NC was synthesized using hydrothermal and high-temperature pyrolysis strategies for oxygen reduction reaction (ORR). The abundant vacancies and synergistic coupling of metallic Co with MnO precisely tuned the electronic configuration, resulting in enhanced electron transport within Co/MnO@NC. Research indicates that the effective Co/MnO@NC ORR catalyst demonstrated elevated peak power densities, reaching 217.7 in liquid-state and 63.3 mW cm−2 in solid-state zinc-air batteries. [Display omitted] • Spherical Co/MnO@NC is synthesized by a hydrothermal-pyrolysis strategy. • The catalyst displays notable ORR activity (J L = 5.1 mAcm−2) comparable to Pt/C. • Aqueous/solid-state ZABs exhibit high power density (217.7/63.3 mW cm−2). • Vacancies, conductivity and hydrophilicity dominate the delightful performance. The pursuit of efficient and economically viable catalysts for liquid/solid-state zinc-air batteries (ZABs) is of paramount importance yet presents formidable challenge. Herein, we synthesized a vacancy-rich cobalt/manganese oxide catalyst (Co/MnO@NC) stabilized on a nitrogen-doped mesoporous carbon (NC) nanosphere matrix by leveraging hydrothermal and high-temperature pyrolysis strategy. The optimized Co/MnO@NC demonstrates fast reaction kinetics and large limiting current densities comparable to commercial Pt/C in alkaline electrolyte for oxygen reduction reaction (ORR). Moreover, the Co/MnO@NC serves as an incredible cathode material for both liquid and flexible solid-state ZABs, delivering impressive peak power densities of 217.7 and 63.3 mW cm−2 and robust long-term stability (459 h), outperforming the state-of-the-art Pt/C and majority of the currently reported catalysts. Research indicates that the superior performance of the Co/MnO@NC catalyst primarily stems from the synergy between the heightened electrical conductivity of metallic Co and the regulatory capacity of MnO on adsorbed oxygen intermediates. In addition, the abundance of vacancies regulates the electronic configuration, and superhydrophilicity facilitates efficient electrolyte diffusion, thereby effectively ensuring optimal contact between the active site and reactants. Besides, the coexisting NC layer avoids the shedding of active sites, resulting in high stability. This work provides a viable approach for designing and advancing high-performance liquid/solid-state ZABs, highlighting the great potential of energy storage technology. [ABSTRACT FROM AUTHOR]

A series of novel Mn6Zr1-xCox denitrification catalysts were prepared by the co-precipitation method. The effect of co-modification of MnOx catalyst by zirconium and cobalt on the performance of NH3-SCR was studied by doping transition metal cobalt into the Mn6Zr1 catalyst. The ternary oxide catalyst Mn6Zr0.3Co0.7 can reach about 90% of NOx conversion in a reaction temperature range of 100-275°C, and the best NOx conversion can reach up to 99%. In addition, the sulfur resistance and water resistance of the Mn6Zr0.3Co0.7 catalyst were also tested. When the concentration of SO2 is 200ppm, the NOx conversion of catalyst Mn6Zr0.3Co0.7 is still above 90%. 5 Vol% H2O has little effect on catalyst NOx conversion. The results showed that the Mn6Zr0.3Co0.7 catalyst has excellent resistance to sulfur and water. Meanwhile, the catalyst was systematically characterized. The results showed that the addition of zirconium and cobalt changes the surface morphology of the catalyst. The specific surface area, pore size, and volume of the catalyst were increased, and the reduction temperature of the catalyst was decreased. In conclusion, the doping of zirconium and cobalt successfully improves the NH3-SCR activity of the catalyst. [ABSTRACT FROM AUTHOR]

In this paper, MnOx/TiO2 catalysts with different manganese contents were prepared by using vacuum over-impregnation method to support manganese on TiO2 support. However, the activity temperature window was narrow and the denitrification efficiency was only 265–365 °C in the temperature zone above 80%. Therefore, doping W was used to improve the high temperature activity and broaden the activity temperature window. The experimental results show that the active temperature window of the catalyst is expanded to 260–550 °C when doping 20%WO3. The effects of tungsten doping on the structure and surface properties of the catalysts were investigated by XRD, TEM, Raman, XPS, H2-TPR and NH3-TPD. It is found that the increase of manganese content would increase the ratio of Mn4+ and Oα, and then improve the NH3-SCR activity at low temperature. Tungsten doping can provide more strong acid sites and improve the high temperature activity of the catalyst by inhibiting the oxidation of ammonia. [ABSTRACT FROM AUTHOR]

The use of manganese oxide (MnOx)-based catalysts has gained significant recognition as a promising solution for the sustainable synthesis of value-added chemicals. These catalysts possess notable qualities such as exceptional catalytic performance, cost-effectiveness, stability, and environmentally friendly properties. This review provides an overview of three typical processes for constructing novel MnOx-based catalysts through vacancy engineering, facet engineering, and crystal-phase engineering. It then discusses advancements made in the past five years in the sustainable synthesis of value-added chemicals using these MnOx-based heterogeneous catalysts. This includes the aerobic oxidation of alcohols and hydrocarbons, homo/cross-coupling of C–N/N＝N bonds, and biomass transformation. The review emphasizes the crucial role played by vacancy engineering, crystal-phase engineering, and facet engineering of MnOx-based heterogeneous catalysts in sustainable chemical synthesis. Lastly, it discusses the general challenges and future directions of this exciting area of research. [ABSTRACT FROM AUTHOR]

As well known, the industrial methanation process needs highly active and stable catalysts obtained from cheap and abundant elements. In this work, we propose a high-loaded Ni/Al2O3 catalyst promoted by manganese. Among them, the 20Ni2Mn/Al2O3 catalyst exhibits the best CO2 conversion (90.5%) and excellent methanation stability at 250 °C. In addition, the roles of the Mn promoter on CO2 conversion and selectivity were investigated in detail. The features of natural and promoted catalysts are described through XRD, XRF, BET, TEM, H2-TPR, CO2-TPD, and operando DRIFTS techniques. Based on various characterization results, the addition of Mn will greatly reduce the Ni particle size and improve the Ni dispersion on the alumina support. Furthermore, compared to the unpromoted catalyst, Mn promoted catalysts show better reducibility and have more medium basic sites. And these medium basic sites are favorable to the adsorption and activation of CO2. In-situ DRIFTS experiments for CO2 methanation reveal that manganese could promote the monodentate carbonate hydrogenated to formate rapidly, which could be faster converted towards CH4, contributing to significantly improved activity of the Mn promoted Ni/Al2O3 catalyst. [ABSTRACT FROM AUTHOR]

This work describes the depolymerization of several polyester and polycarbonate plastic waste in value‐added compounds catalyzed by the air stable, cheap and commercially available manganese compounds Mn(OTf)2, Mn2(CO)10, MnBr(CO)5, and MeCpMn(CO)3 using boranes and silanes as the reducing agents with good to excellent yields. Commercial heterogeneous manganese catalyst, manganeses(II) ethyl/butyl phosphonate silica (Si‐Mn), has also proven to be very efficient in the reductive depolymerization of a variety of polyesters and the polycarbonate PC.BPA. The use of Mn(OTf)2, Mn2(CO)10 and Si‐Mn in consecutive depolymerization of polyesters is also investigated, showing that these catalysts remain their excellent activity after several reactions. [ABSTRACT FROM AUTHOR]

A manganese pincer complex Mn‐2 for the homogeneously catalysed conversion of CO/H2 to methanol was developed using a novel PNP ligand design. Compared to the previous state‐of‐the‐art catalyst system Mn‐1, the presented Mn‐2 with different substituents at the P‐atoms led to a significant increase of the reaction rate (TOF up to >1600 h−1). [ABSTRACT FROM AUTHOR]

[Display omitted] Selective oxidations are important reactions in organic synthesis for fine chemical industry and conventional methods are expensive and produce a lot of toxic wastes. Herein, we demonstrate a facile and environmentally benign technique for liquid phase selective oxidation based on graphene-supported Mn single-atom-catalyst (SAMn-G) for efficient peroxymonosulfate (PMS) activation. The active Mn component in the developed SAMn-G catalyst reached single-atomic dispersion on graphene substrate via the coordination of individual Mn atoms with the doped N from the graphene framework. SAMn-G activated PMS via a nonradical-dominated pathway, which could convert aromatic alcohols into aldehydes or ketones at a mild temperature. The SAMn-G catalyst exhibited superior conversion and aldehyde selectivity in alcohol oxidation in comparison with their counterpart catalysts possessing either homogeneous Mn ions or oxide particles. The high activation efficiency of SAMn-G is due to the synergistic effect between Mn atoms and graphene substrate, as well as the dominated reaction pathway from nonradical oxidation, which is more selective than these free radicals to oxidize the alcohols. Concerted experimental evidence indicates that the non-radical oxidation process was highly possible to follow the electron transfer mechanism by PMS/organic adsorption on the surface of the catalyst. This study provides a fundamental understanding of PMS activation mediated by single atom catalyst for organic synthesis and the achieved insights can also help the catalyst design for other liquid phase selective oxidation processes. [ABSTRACT FROM AUTHOR]

The increasing concentration of CO2 in the atmosphere and its impact on the climate are matters of significant concern. Extensive research is being conducted on molecular catalysts to electrochemically reduce CO2 into valuable products to disrupt the unidirectional carbon flow. This study compares two manganese bipyridine catalysts, tailored with four or two benzylic diethylamine groups in the secondary coordination sphere. Either of these amine‐bearing scaffolds positioned close to the Mn center serves as effective proton relays to facilitate the formation of the corresponding Mn hydride intermediate. Alongside competitive H2 evolution, the reaction of this crucial intermediate with CO2 leads to formate. Our findings underscore the pronounced influence of external Brønsted acids on product selectivity. Notably, when employing the catalyst bearing four amine groups, the HCOO−/H2 ratio varies from 81 : 3 with 1.0 M iPrOH to 16 : 64 with 1.0 M PhOH, while the Mn complex adorned with two amine pendant groups consistently favors HCOO−, irrespective of the utilized proton sources. Infrared spectroelectrochemistry and density‐functional theory calculations unveil distinct disparities in the reactivity of the Mn hydrides toward CO2 due to the change of ligand bulkiness in the two cases. This work substantiates the importance of modulating spatial accessibility while modifying the second sphere encompassing molecular catalysts. [ABSTRACT FROM AUTHOR]

Manganese(I) carbonyl complexes bearing a MACHO‐type ligand (HN(CH2CH2PR2)2) readily react in their amido form with CO2 to generate 4‐membered {Mn−N−C−O} metallacycles. The stability of the adducts decreases with the steric demand of the R groups at phosphorous (R=isopropyl>adamantyl). The CO2‐adducts display generally a lower reactivity as compared to the parent amido complexes. These adducts can thus be interpretated as masked forms of the active amido catalysts and potentially play important roles as off‐loop species or branching points in catalytic transformations of carbon dioxide. [ABSTRACT FROM AUTHOR]

Catalysts containing manganese as the primary active component have emerged as promising candidates for ultra-low temperature NH3-SCR applications. To enhance the catalytic activity of these catalysts, a series of Mn-FeOX catalysts were prepared using the co-precipitation method. This study focuses on investigating the appropriate calcination process for catalyst preparation using different precipitants, namely NaOH, NH3-H2O and Na2CO3. The results revealed that catalysts prepared with Na2CO3 as the preferred precipitant and calcined at 330∘C exhibited exceptional NOx removal efficiency, exceeding 90% at a temperature of 60∘C and GHSV = 30,000 h − 1 , which demonstrated this catalyst's remarkable low-temperature reduction capability. Detailed characterization demonstrated that the MnOX catalysts synthesized through this process possessed an amorphous structure, superior pore structure and the highest Fe 3 + content. These findings offer valuable insights for optimizing the preparation conditions of Mn-FeOX catalysts in ultra-low temperature denitrification applications. In this study, the precipitation and calcination processes during the preparation of Mn-FeOX catalysts were improved. The catalysts prepared by selecting Na2CO3 at the appropriate calcination temperatures have the advantages of excellent pore structure and stronger redox capacity in comparison, and the NOX removal rate of more than 90% at ultra-low temperature of 60∘C is impressive. This provides valuable insights for the preparation of Mn-FeOX catalysts with excellent low-temperature activity. [ABSTRACT FROM AUTHOR]

Novel bamboo activated carbon (BAC) catalysts decorated with manganese oxides (MnOx) were prepared with varying MnOx contents through a facile one-step redox reaction. Due to the physical anchoring effect of the natural macropore structure for catalyst active components, homogeneous MnOx nanoparticles (NPs), and high specific surface area over catalyst surface, the BAC@MnOx-N (N = 1, 2, 3, 4, 5) catalyst shows encouraging adsorption and catalytic oxidation for indoor formaldehyde (HCHO) removal at room temperature. Dynamic adsorption and catalytic activity experiments were conducted. The higher Smicro (733 m2/g) and Vmicro/Vt (82.6%) of the BAC@MnOx-4 catalyst could facilitate its excellent saturated and breakthrough adsorption capacity (5.24 ± 0.42 mg/g, 2.43 ± 0.22 mg/g). The best performer against 2 ppm HCHO is BAC@MnOx-4 catalyst, exhibiting a maximum HCHO removal efficiency of 97% for 17 h without any deactivation as RH = 0, which is higher than those of other MnOx-based catalysts. The average oxidation state and in situ DRIFTS analysis reveal that abundant oxygen vacancies on the BAC@MnOx-4 catalyst could be identified as surface-active sites of decomposing HCHO into the intermediate species (dioxymethylene and formate). This study provides a potential approach to deposit MnOx nanoparticles onto the BAC surface, and this hybrid BAC@MnOx material is promising for indoor HCHO removal at room temperature. [ABSTRACT FROM AUTHOR]

The sustainable solution to the environmental problem of polymeric materials calls for efficient and well‐controlled ring‐opening polymerization catalytic systems. Inspired by the highly reactive and stereospecific bimetallic catalysts, three kinds of bimetallic Salen‐Mn catalysts supported by biaryl linking moieties are synthesized and applied to polymerization catalysis of lactide (LA) and ϵ‐caprolactone (ϵ‐CL) in this work. The polymerization is initiated in situ by the ring‐opening of epoxide compounds, in which the ionic cocatalyst could accelerate the reaction process. The Mn−Mn coordination effect contributes to the higher activity and iso‐selectivity towards LA compared to the mononuclear Salen‐Mn catalyst. The reactivity and stereoselectivity are determined by the conformation of catalysts, specifically the Mn−Mn separation and dihedral angle. Finally, the CO2‐controlled switchable polymerizations are carried out with LA and ϵ‐CL. The reversibility of the on‐off switching operation is influenced by the combination between CO2 molecules and active species. The success in binuclear Salen‐Mn catalysts not only expands the range of bimetallic catalyst analogues but also claims the promising potential of Mn‐based catalysts in practical and theoretical research. [ABSTRACT FROM AUTHOR]

Coconut shell–activated carbon is a highly promising catalytic carrier due to its chemical stability and high porosity. Meanwhile, manganese-based oxidants are very effective catalysts in NH3-SCR, but their instability restricts their use. In an attempt to create catalysts that perform well at low temperatures, this study characterized nitric acid-modified coconut shell-activated carbon carriers at different concentrations using N2 adsorption-desorption, XRD, BET, XPS, DRIFTS, and other methods. By doping with Cu and Mn as the main active substance, optimal Mn-Cu composite catalysts were prepared. The study found that Mn7Cu3/AC-B catalyst had the best activity at low temperatures, achieving up to 99% denitrification efficiency at 225 °C. The catalyst had the highest content of Mn4+, Cu2+, and Oα, which favored the reaction and made the catalyst more resistant to water and sulfur. The use of the appropriate concentration of nitric acid helps to remove carrier impurities and improve carrier structural parameters, thus enabling uniform dispersion of active substances and facilitating the reaction. Moreover, copper and manganese have a synergistic effect, and the composite catalysts have higher redox capacity, catalyst acidic sites, and N2 selection compared to single manganese catalysts. This study aims to prepare better resistant catalysts for low-temperature reactions and contribute to the optimization of manganese-based catalysts. [ABSTRACT FROM AUTHOR]

Unraveling the atomistic and the electronic structure of solid–liquid interfaces is the key to the design of new materials for many important applications, from heterogeneous catalysis to battery technology. Density functional theory (DFT) calculations can, in principle, provide a reliable description of such interfaces, but the high computational costs severely restrict the accessible time and length scales. Here, we report machine learning-driven simulations of various interfaces between water and lithium manganese oxide (LixMn2O4), an important electrode material in lithium ion batteries and a catalyst for the oxygen evolution reaction. We employ a high-dimensional neural network potential to compute the energies and forces several orders of magnitude faster than DFT without loss in accuracy. In addition, a high-dimensional neural network for spin prediction is utilized to analyze the electronic structure of the manganese ions. Combining these methods, a series of interfaces is investigated by large-scale molecular dynamics. The simulations allow us to gain insights into a variety of properties, such as the dissociation of water molecules, proton transfer processes, and hydrogen bonds, as well as the geometric and electronic structure of the solid surfaces, including the manganese oxidation state distribution, Jahn–Teller distortions, and electron hopping. [ABSTRACT FROM AUTHOR]

The characteristics of Mn catalysts supported on different carriers (SiO2 and BEA zeolite) in the processes of ozone decomposition and ozone-catalytic oxidation (OZCO) of volatile organic compounds (VOCs) were studied using n-butane as an example. The parent SiO2 was inactive in the test reactions, and the characteristics of Mn/SiO2 were determined by the catalytic properties of the supported MnOx oxide. In contrast to SiO2, BEA zeolite demonstrated significant catalytic activity, although at a temperature 50°C higher than that for Mn/BEA. The data obtained allowed us to conclude that the catalytic characteristics of Mn/BEA at 30–100°C were also determined by the Mn component of the catalyst. At higher temperatures, the catalytic properties of BEA significantly affected the course of the OZCO process. The zeolite carrier improved hydrocarbon conversion at 100–200°C and decreased the amount of ozone required for the OZCO process over Mn/BEA. [ABSTRACT FROM AUTHOR]

New treatment methods based on biologically produced metal catalysts and reagents are being developed for the removal of pollutants. Biogenic manganese oxide (BMO) is one of the biogenic metal oxide types that have attracted attention especially in recent years. BMO is a suitable material for the removal of pollutants due to its notable activity and structural diversity. However, the role of biogenic manganese oxides in persulfate activation is so far unclear. In the present study, the biogenic manganese oxide was used as a catalyst in persulfate (PS) activation for the atrazine removal from aqueous solution. BMO/PS system was effective for removing the atrazine. The removal efficiency of the atrazine by BMO/PS system decreased with increasing pH. The removal efficiency increased with the increasing PS amount. Increasing the temperature facilitated the decomposition of the atrazine. It was revealed that 99.9% of the atrazine was removed in 300 min at pH 3 and 50 °C (Co: 5 mg/L, BMO: 2 g/L, PS: 1.4 g/L). In this system, the efficiency and stability of the catalyst decreased over three cycles. Sulfate and hydroxyl radicals were both involved in the atrazine removal. Based on the detected decay by-products, two degradation pathways have been proposed. The BMO were characterized via SEM–EDX, XRD, FTIR, and TGA techniques. This system reduced the environmental toxicity of atrazine. As a result, it has been revealed that this innovative material, BMO, has persulfate activation potential as an effective solution to the problem of persistent organic pollutants present in aquatic environments. [ABSTRACT FROM AUTHOR]

This study reports an efficient and green one‐step method for synthesizing thiophene‐substituted ketones from 2‐thiophenemethanol and ketones via dehydrogenative coupling using manganese complexes as catalysts. The manganese complex demonstrated a broad applicability under mild conditions and extended the range of usable substrates. Utilizing this strategy, we carried out an efficient and diverse reaction of ketones with 2‐thiophenemethanol, and successfully synthesized a series of thiophene‐substituted saturated ketones and α, β‐unsaturated ketones in good isolated yields. [ABSTRACT FROM AUTHOR]

[Display omitted] The combination of chemo- and biocatalysts to perform one-pot synthetic route has presented great challenges for decades. Herein, glutamate oxidase (GLOX) and trimanganese tetraoxide (Mn 3 O 4) nanocrystals were combined for the first time by one-step biomineralization to construct a mimic multi-enzyme system (GLOX@Mn 3 O 4) for chemoenzymatic synthesis of α‑ketoglutaric acid (α‑KG). Mn 3 O 4 not only served as a support for the enzyme immobilization, but also contributed its catalytic activity to co-operate with natural enzymes for the cascade reactions. The as-synthesized chemo-enzyme catalysts with directly contacted catalytic sites of the enzyme and inorganic catalyst maximizes the substrate channeling effffects for in situ rapid decomposition of the oxidative intermediate, H 2 O 2 , during the enzymatic oxidation of sodium glutamate, thus relieving the inhibition of H 2 O 2 accumulation for GLOX. Benefiting from the excellent stability and reusability of GLOX@Mn 3 O 4 , a nearly 100% conversion (99.7%) of l -glutamate to α-KG was achieved, over 4.7 times higher than that of the free GLOX system (21.2%). This work provides a feasibility for constructing a high-performance chemo-enzyme catalyst for cascade catalysis, especially for those reactions with toxic intermediates. [ABSTRACT FROM AUTHOR]

Hydrogen peroxide is considered a highly powerful oxidant and can oxidize thiophene contaminant compounds in diesel. In this work, a trickle bed electrochemical reactor (TBER) with multiple cells is investigated for diesel desulfurization, which is intensified with a highly effective electrocatalyst, MnO2, for in situ hydrogen peroxide production. The multiple cell TBER demonstrates much enhanced oxidation of dibenzothiophene (DBT) in diesel flowing with alkaline electrolyte through the TBER. A 500 ppm DBT was completely oxidized in situ in the multi-cell TBER in 2.5 h, indicative of highly efficient deep desulfurization of diesel fuel within the multi-cell TBER. [ABSTRACT FROM AUTHOR]

Keywords: manganese; nickel; palladium; bimetallic catalysis; indole; oxidation; C-H activation EN manganese nickel palladium bimetallic catalysis indole oxidation C-H activation 3625 3631 7 10/19/23 20231102 NES 231102 Graph I N i -Heterocyclic scaffolds are crucial in synthetic and medicinal chemistry. Subsequently, imine formation and C-H activation reaction were carried out and indole B 5a b was isolated in 19% total yield (76% yield was obtained in the C-H activation step). The filtration step seems to be crucial for the Pd-catalyzed C-H activation reaction, indicating that the presence of the Ni catalyst to a great extent inhibited the Pd-catalyzed reaction leading to a poor overall yield of the indole B 5a b . In the case of I m i -(trifluoromethyl)aniline ( B 3c b ), its corresponding imine B 4c b underwent cyclization at the less-hindered position affording 6-substituted indole B 5c b in 34% yield (yield from last step). [Extracted from the article]

Peroxomanganese species have been proposed as key intermediates in the catalytic cycles of both manganese enzymes and synthetic catalysts. However, many of these intermediates have yet to be observed. Here, we report the formation of a series of intermediates, each generated from the reaction of the mononuclear MnIII–hydroxo complex [MnIII(OH)(dpaq2Me)]+ with hydrogen peroxide under slightly different conditions. By changing the acidity of the reaction mixture and/or the quantity of hydrogen peroxide added, we are able to control which intermediate forms. Using a combination of electronic absorption, 1H NMR, EPR, and X-ray absorption spectroscopies, as well as density functional theory (DFT) and complete active space self-consistent field (CASSCF) calculations, we formulate these intermediates as the bis(μ-oxo)dimanganese(III , IV) complex [MnIIIMnIV(μ-O)2(dpaq2Me)2]+, the MnIII–hydroperoxo complex [MnIII(OOH)(dpaq2Me)]+, and the MnIII–peroxo complex [MnIII(O2)(dpaq2Me)]. The formation of the MnIII–hydroperoxo species from the reaction of a MnIII–hydroxo complex with hydrogen peroxide mimics an elementary reaction proposed for many synthetic manganese catalysts that activate hydrogen peroxide. [ABSTRACT FROM AUTHOR]

Synthetic manganese catalysts that activate hydrogen peroxide perform a variety of hydrocarbon oxidation reactions. The most commonly proposed mechanism for these catalysts involves the generation of a manganese(III)-hydroperoxo intermediate that decays via heterolytic O–O bond cleavage to generate a Mn(V)-oxo species that initiates substrate oxidation. Due to the paucity of well-defined MnIII-hydroperoxo complexes, MnIII-alkylperoxo complexes are often employed to understand the factors that affect the O–O cleavage reaction. Herein, we examine the decay pathways of the MnIII-alkylperoxo complexes [MnIII(OOtBu)(6Medpaq)]+ and [MnIII(OOtBu)(N4S)]+, which have distinct coordination environments (N5− and N4S−, respectively). Through the use of density functional theory (DFT) calculations and comparisons with published experimental data, we are able to rationalize the differences in the decay pathways of these complexes. For the [MnIII(OOtBu)(N4S)]+ system, O–O homolysis proceeds via a two-state mechanism that involves a crossing from the quintet reactant to a triplet state. A high energy singlet state discourages O–O heterolysis for this complex. In contrast, while quintet–triplet crossing is unfavorable for [MnIII(OOtBu)(6Medpaq)]+, a relatively low-energy single state accounts for the observation of both O–O homolysis and heterolysis products for this complex. The origins of these differences in decay pathways are linked to variations in the electronic structures of the MnIII-alkylperoxo complexes. [ABSTRACT FROM AUTHOR]

Manganese catalysts that activate hydrogen peroxide carry out several different hydrocarbon oxidation reactions with high stereoselectivity. The commonly proposed mechanism for these reactions involves a key manganese(III)-hydroperoxo intermediate, which decays via O–O bond heterolysis to generate a Mn(V)–oxo species that institutes substrate oxidation. Due to the scarcity of characterized MnIII–hydroperoxo complexes, MnIII–alkylperoxo complexes are employed to understand factors that affect the mechanism of the O–O cleavage. Herein, we report a series of novel complexes, including two room-temperature-stable MnIII–alkylperoxo species, supported by a new amide-containing pentadentate ligand (6Medpaq5NO2). We use a combination of spectroscopic methods and density functional theory computations to probe the effects of the electronic changes in the ligand sphere trans to the hydroxo and alkylperoxo units to thermal stability and reactivity. The structural characterizations for both MnII(OTf)(6Medpaq5NO2) and [MnIII(OH)(6Medpaq5NO2)](OTf) were obtained via single-crystal X-ray crystallography. A perturbation to the ligand sphere allowed for a marked increase in reactivity towards an organic substrate, a modest change in the distribution of the O–O cleavage products from homolytic and heterolytic pathways, and little change in thermal stability.

Manganese oxide nanowires (MONW) combined with carbon nanostructures were synthesized using three different carbon materials, and their effect on the activity towards Oxygen Reduction Reaction (ORR) and Oxygen Evolution Reaction (OER) was investigated in alkaline electrolytes. The carbon structures were carbon nanofibers (CNF), multiwall carbon nanotubes (CNT) and reduced graphene oxide (rGO). Both MONW and carbon nanostructures were characterized by X-ray diffraction, scanning and transmission electron microscopy, N2 physisorption and X-ray photoelectron spectroscopy. The electrochemical activity was assessed in a three-electrode cell. Composite MONW/CNF showed the best activity towards ORR, and MONW/rGO exhibited the highest activity towards OER of the series. The addition of the carbon nanostructures to MONW increased the number of electrons transferred in the ORR, indicating a synergistic effect between the carbon and manganese oxide structures due to changes in the reaction pathway. The analysis of Tafel slopes and electrochemical impedance spectroscopies showed that carbons and MONW catalyze different steps of the reactions, which explains the better activity of the composites. This led us to synthesize a MONW/rGO-CNF composite, where rGO-CNF is a hybrid carbon material. Composite MONW/rGO-CNF showed an improved activity towards ORR, close to the benchmark Pt/C catalyst, and activity towards OER, close to MONW/rGO, and better than the benchmark IrO2 catalyst. It also showed remarkable stability in challenging operation conditions. [ABSTRACT FROM AUTHOR]

Composite heterogeneous catalysts of ferrous and manganese oxalate (FeC2O4/MnC2O4) were prepared via simple chemical co-precipitation. The catalytic performance was evaluated by determining the degradation efficiency of rhodamine B (RhB). Under optimum conditions, 6-1FeMn showed the best catalytic performance, and the degradation efficiency exceeded 95 % within 2 min, which was 1.4 times more than ferrous oxalate. Under a wide pH range (1–8), 6-1FeMn showed high degradation efficiency for RhB with good recyclability and reusability. By characterizing the catalysts before and after the reaction and analyzing the degradation process, a possible mechanism was proposed: Mn2+ and Fe2+ synergistically catalyzed and produced a large number of hydroxyl radicals (·OH) by forming a composite active site for efficient reactivation. Mn3+ accelerated the transfer between Fe2+ and Fe3+. In addition, C2O42− reactivated the active site in situ and enhanced the catalytic properties. This study provides new insight into the catalytic degradation of organic dyes using composite heterogeneous Fenton catalysts. [ABSTRACT FROM AUTHOR]

A dual-zone catalytic systems 10%Mn/Al2O3||10%Ag/Al2O3 has been developed for the low temperature light alkanes oxidation in presence of ozone. The upstream bed (10%Mn/Al2O3) is responsible for the ozone catalytic oxidation (OZCO) of light alkanes, while the downstream bed (10%Ag/Al2O3) provide effective carbon monoxide abatement and O3-slip decomposition. The system demonstrates effective removal of hydrocarbons at 100 °C for a long time. [ABSTRACT FROM AUTHOR]

A series of mixed oxides (Mn‐Mg‐Al) is prepared by coprecipitation via a hydrotalcite route with different manganese ratios. Structural, textural, and redox properties are studied by XRD, N2‐sorption, H2‐TPR, and XPS techniques. MnxMg6‐xAl2‐O mixed oxides (with 0≤x≤6) are tested in the total oxidation of ethanol and toluene, two probe molecules representing respectively oxygenated and aromatic VOCs. Catalysts with higher manganese contents have shown the best catalytic performance for the oxidation of both ethanol and toluene. The surface activity of the materials is mainly related to the presence of manganese species in three different oxidation states (+II, +III, and +IV) in the bulk and on the material's surface. Since high Mn‐content catalysts showed similar physicochemical properties and catalytic activity, Mn4Mg2‐O is selected as the optimal composition of these materials. Furthermore, its aging test is compared to that of noble metal‐based commercial catalysts (Pd/γ‐Al2O3). [ABSTRACT FROM AUTHOR]

The deoxygenation of secondary and tertiary amides to the corresponding amines catalyzed by simple Mn(CO)5Br using Ph2SiH2 or PMHS as the reductant was established. This transformation could proceed under mild conditions without sensitive and specialized external ligands. [Display omitted] • Mn(CO) 5 Br-catalyzed deoxygenation of the secondary and tertiary amides with Ph 2 SiH 2 or PMHS under ligands-free conditions. • (a) using commercial manganese catalyst Mn(CO) 5 Br, (b) no external ligand, (c) mild conditions, and (d) broad substrate scope. Herein, we report the deoxygenation of secondary and tertiary amides enabled by [Mn(CO) 5 Br] with Ph 2 SiH 2 or inexpensive polymethylhydrosiloxane (PMHS) as the reducing agents, which provides expedient access to the corresponding secondary and tertiary amines. The operationally simple transformation proceeds under mild conditions without external ligands and features high catalytic efficacy and good functional-group tolerance. Furthermore, the generality of this developed catalytic system was further demonstrated by the late-stage modification of bioactive molecules. [ABSTRACT FROM AUTHOR]

Atom transfer radical addition of bromonitromethane and 1,2-dibromotetrafluoroethane to alkenes is described. The reaction is performed under blue light irradiation using two catalysts: 4CzIPN and manganese (II) bromide. The cyanoarene photocatalyst serves for the redox activation of starting organic bromide, while the manganese salt facilitates the trapping of the alkyl radical with the formation of the carbon–bromine bond. [ABSTRACT FROM AUTHOR]

Copyright of Inorganic Chemicals Industry is the property of Editorial Office of Inorganic Chemicals Industry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The reactivity of metal‐hydride complexes can be harnessed by the modification of ancillary ligands. With the aim of improving the hydride‐donor ability of the key Mn−H intermediate and reducing steric hindrance, we herein report the rational design of a versatile and efficient NHC‐based NNC‐pincer Mn catalyst for hydrogenation reactions. This newly developed catalyst exhibited higher activity than the corresponding NNP‐pincer Mn catalyst owing to its reduced steric hindrance and enhanced Mn−H σ‐bonding orbital energy level through a π‐antibonding interaction. Using this highly active NNC‐pincer Mn catalyst, a rich array of polar unsaturated compounds (>80 examples) including esters, N‐heteroarenes, amides, carbonates, and urea derivatives, were successfully hydrogenated under relatively mild conditions. This work represents a rare example of a general phosphine‐free Mn‐catalyzed hydrogenation system. [ABSTRACT FROM AUTHOR]

Copyright of Inorganic Chemicals Industry is the property of Editorial Office of Inorganic Chemicals Industry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study investigates the use of MnxOy/Al2O3 and Pt/Al2O3 catalysts for the decomposition of hydrogen peroxide in thrusters. It describes the purpose, procedures, performance, and conclusions coming from the test campaign of the catalyst lifetimes. In particular, eight different propellant samples with two different catalysts were tested twice (in order to exclude uncertainty). Similar operating and starting conditions were applied. All hot tests were performed in a thruster-like catalyst bed configuration with a propellant injector and outlet nozzle. Each bed was filled with the same mass of catalyst (for the same type of catalyst). The results show that platinum is a more effective catalyst than manganese oxides for the decomposition of hydrogen peroxide. The findings have important implications for the development of catalysts for "green" propellants. [ABSTRACT FROM AUTHOR]