Mn Loading Research Articles

Degradation of benzene, toluene, and xylene with high gaseous hourly space velocity by double dielectric barrier discharge combined with Mn3O4/activated carbon fibers

A novel strategy for the degradation of high gaseous hourly space velocity benzene, toluene, and xylene (BTX) by double dielectric barrier discharge (DDBD) coupled with Mn3O4/ activated carbon fiber (ACF) catalysts was proposed in this work. A series of Mn3O4/ACF catalysts were synthesized using the hydrothermal method and characterized. The results showed that all the prepared catalysts could improve the degradation of BTX in the DDBD system and inhibit the production of ozone. Among the catalysts with different Mn loading, the 5.6%Mn3O4/ACF, with the highest Mn(+3) content (43.2%) and the highest absorbed oxygen content (38.5%), presented the best catalytic performance. In the 5.6% Mn3O4/ACF + DDBD system, the degradation efficiency of benzene, toluene and xylene could reach 49.9%, 79.7% and 97.1%, respectively, with a specific input energy of 400 J l−1. The carbon balance and CO2 selectivity, meanwhile, were 83.3% and 51.1%, respectively. It seemed that Mn(+3) and absorbed oxygen content could be a reference for the catalytic performance of Mn3O4/ACF catalysts. The higher the Mn (III) and absorbed oxygen, the better the catalytic performance of the Mn3O4/ACF catalysts. The organic by-products were identified by chromatography-mass spectrometry, and a possible reaction mechanism of BTX in the DDBD reactor and catalyst surface was proposed based on the composition of organic by-products.

Lipid Anchoring Improves Lubrication and Wear Resistance of the Collagen I Matrix.

Osteoarthritis is a prevalent degenerative joint disease characterized by progressive articular cartilage loss and destruction. The resultant increase in friction causes severe pain. The collagen I matrix (COL I) has been used clinically for cartilage repair; however, how COL I acts at cartilage surfaces is unclear. Here, we studied adsorption and lubrication of synovial fluid components, albumin, γ-globulin, and the phospholipid DPPC, on COL I under physiological conditions using surface plasmon resonance and an in situ sensing surface force apparatus. Our results revealed COL I had poor lubrication ability, a fairly high coefficient of friction (COF, μ = 0.651 ± 0.013), and surface damage under a 7 mN load. DPPC formed an improved lubricating layer on COL I (μ = 0.072 ± 0.016). In sharp contrast, albumin and γ-globulin exhibited poor lubrication with an order of magnitude higher COF but still provided benefits by protecting COL I from wear. Hence, DPPC on COL I may help optimize COL I implantation design.

Assessment of heavy metal pollution in soil samples from a gold mining area in Osun State, Nigeria using proton-induced X-ray emission

This study identified and determined the concentration of heavy metal contaminants in Igun, Ijana-Gada and Igbadae gold mining sites using Particle Induced X-ray Emission (PIXE) technique. This was with a view to providing information on various heavy metal concentrations, potential sources of metals contamination and pollution load at Igun, Ijana-Gada and Igbadae gold mining sites.A total of thirty soil samples were collected randomly from Igun, Ijana-Gada and Igbadae gold mining sites in the Ilesha area, Osun State. Twelve samples were collected each from Igun and Ijana-Gada sites; while six samples were collected from Igbadae site. The soil samples were processed and analyzed for selected heavy metals (Fe, Mn, Cu, Zn, Cr, M, V and Fe). A Multivariate statistics approach (Pearson Correlation Matrix and Principal Component Analysis) was used on the data for identification of contamination sources.The heavy metal concentrations in the studied soils decreased in the following order: Fe > Ti > Mn > V > Cr > Zn > Pb > Cu with mean value of Fe (84,470.60 mg/kg), Ti (15,337.30 mg/kg), Mn (576.80 mg/kg), V (465.90 mg/kg), Cr (304.10 mg/kg), Zn (103.90 mg/kg), Pb (38.60 mg/kg), and Cu (26.00 mg/kg). The result obtained from the assessment of heavy metal pollution using Enrichment Factor (EF), Pollution Load Index (PLI), and Pollution Index (PI) confirmed that Igun, Ijana-Gada, and Igbadae soils/mine-tailings were polluted in the range from slightly through moderately polluted up to highly polluted. Principal Component Analysis (PCA) extracted three major components: PC1with loading of Fe, V, Zn, and Cu, PC2 with high loading of Ti and Mn while PC3 with the contribution of Pb and Cr. This was corroborated by Pearson Correlation Matrix (PCM) for the analyzed elements.The study revealed that the soils and mine tailings from the study area were polluted with heavy metals especially V, Ti and Cr from anthropogenic sources with little crustal material contributions thereby posing serious environmental and health concerns.

Arsenic adsorption enhancement performances of Mn-modified γ-Al2O3 with flue gas constituents involved

Some flue gas constituents have negative effects on As2O3 adsorption of γ-Al2O3 so promoting arsenic adsorption performances under complicated flue gas conditions is necessary based on previous studies. In this study, γ-Al2O3 is modified with manganous nitrate and then Mn-modified γ-Al2O3 is used as the adsorbents in experiments. Besides, molecular dynamics (MD) simulations and density functional theory (DFT) calculations are performed to explore mechanisms of how loadings of Mn enhance arsenic adsorption features of γ-Al2O3 when being affected by flue gas constituents in microscale and mesoscale, respectively. As for DFT calculations, it is uncovered that electron transfer/interaction among As2O3, flue gas constituents and Mn-modified γ-Al2O3 mostly influences arsenic adsorption. For MD simulations, it is expounded that the collision and aggregation of As2O3 and flue gas constituent molecules have most impact on arsenic adsorption. As far as experiments are concerned, they are conducted to show the macroscopic characterizations of arsenic adsorption performances, corresponding to results of DFT calculations and MD simulations. The understanding of these three different aspects could supply significant references for utilization of Mn-modified γ-Al2O3 in real industries to remove arsenic under complex flue gas conditions.

Oxidative coupling of methane over MnO2/ZrO2 catalyst in supercritical water: A parametric study

Hydrocarbons production with carbon numbers above C2 through methane coupling has been a target of many researches in the past decades. Recently we discovered that the reaction also occurs under supercritical water conditions. In this work, effects of reaction parameters such as catalyst Mn loading, charged catalyst amount, reaction time as well as reaction pressures and temperatures on the catalytic methane coupling under sub- and supercritical water environment were explored over MnO2/ZrO2 catalyst using a batch reactor. It was found within the investigated parameters that methane coupling activity was maximum at 12–35 MPa, 365–400 °C, 10 wt% Mn loading on ZrO2, reaction time 5 min and 1.0 g catalyst charging. It was conjectured from the temperature–pressure mapping of products that the reaction pathway of hydrocarbon formation over MnO2/ZrO2 is not the same with methanol formation pathway.

Protective Effect of Monoisoamyl-2, 3-Dimercaptosuccinic Acid against Manganese-induced Neurotoxicity in Rats.

Apart from being an essential heavy metal, Manganese (Mn) serves as an important component of the antioxidant enzyme system in humans. Overexposure to manganese leads to the development of manganism, which is characterized by motor dysfunction along with neurodegeneration. The management of manganism often utilizes chelation therapy. In this regard, Monoisoamyl-2, 3-Dimercaptosuccinic Acid (MiADMSA) has been reported as a novel arsenic chelator, due to the presence of vicinal sulfhydril group. MiADMSA has been reported to reduce the level in divalent ions (like copper) therefore, it may be hypothesized that MiADMSA would be helpful in Mn-induced neurotoxicity. This study is envisaged to explore the protective effect of MiADMSA on Mn-induced neurotoxicity. Mn exposure was carried out by intraperitoneal administration of Mn (as manganese chloride, 10 mg/kg; i.p.). The animals were treated with MiADMSA (50 mg/kg; p.o.) either alone or in combination with Mn. The effect of different treatments on neurobehavioral functions was observed by assessing spontaneous locomotor activity, motor rotarod test, and depression-like behavior in the forced swim test. After behavioral evaluations, all the animals were sacrificed and the brain and liver were isolated for metal estimations. Mn exposure leads to loss of motor coordination as observed in spontaneous locomotor activity and rotarod test. However, treatment with MiADMSA significantly improved motor impairments as compared to Mn exposed animals. Accumulation of Mn in the liver and brain has been recorded with Mn exposure; however, MiADMSA treatment significantly reduced the Mn content from the liver and brain. The outcome of the study suggests that treatment with MiADMSA reversed Mn-induced neurotoxicity by reducing Mn load. Therefore, the use of MiADMSA may be suggested in manganese toxicity, after careful investigation.

Reverse Micelle Strategy for the Synthesis of MnO x -TiO2 Active Catalysts for NH3-Selective Catalytic Reduction of NO x at Both Low Temperature and Low Mn Content.

MnOx–TiO2 catalysts (0, 1, 5, and 10 wt % Mn nominal content) for NH3-SCR (selective catalytic reduction) of NOx have been synthesized by the reverse micelle-assisted sol–gel procedure, with the aim of improving the dispersion of the active phase, usually poor when obtained by other synthesis methods (e.g., impregnation) and thereby lowering its amount. For comparison, a sample at nominal 10 wt % Mn was obtained by impregnation of the (undoped) TiO2 sample. The catalysts were characterized by using an integrated multitechnique approach, encompassing X-ray diffraction followed by Rietveld refinement, micro-Raman spectroscopy, N2 isotherm measurement at −196 °C, energy-dispersive X-ray analysis, diffuse reflectance UV–vis spectroscopy, temperature-programmed reduction technique, and X-ray photoelectron spectroscopy. The obtained results prove that the reverse micelle sol–gel approach allowed for enhancing the catalytic activity, in that the catalysts were active in a broad temperature range at a substantially low Mn loading, as compared to the impregnated catalyst. Particularly, the 5 wt % Mn catalyst showed the best NH3-SCR activity in terms of both NOx conversion (ca. 90%) and the amount of produced N2O (ca. 50 ppm) in the 200–250 °C temperature range.

Mechanical behavior in the interior and boundary of magnesium aluminate spinel (MgAl2O4) grain under nanoindentation.

The understanding of mechanical behavior in magnesium aluminate spinel (MgAl2O4) at the nanoscale lays a foundation for its material removal mechanism in ultraprecision machining. Nanoindentation tests are carried out in the interior and boundary of spinel grain with different loads. An obvious indentation size effect exhibits in both of these areas. First, the nano-hardness and elastic modulus decrease, followed by stabilization due to an increase of pressure. The measured elastic modulus, hardness, and fracture toughness of the grain interior are 277.7±8.4GPa, 19.79±0.83GPa, and 1.12±0.02MPa⋅m1/2, respectively. Deformation of spinel transits from elastic to plastic at approximately 0.8 mN load, which corresponds to the discontinuous steps of load-displacement curves. By comparing the fracture toughness and the residual indent morphology, the grain boundary exhibits lower brittleness than the grain interior. Radial cracks form on the grain surface as indentation load exceeds 29 mN, whose propagation is influenced by the loading conditions and the grain boundary effect.

Effect of flue gas components on the NO removal and element mercury oxidation performance of Mn-modified low-temperature catalyst

Abstract The development of a low-temperature water and sulfur-resistant catalyst with high efficiency of NO removal and element mercury Hg(0) oxidation performance is one of the main directions for the synergistic removal of multiple pollutants from flue gas. The transition metal Mn is used to modify the V-W/Ti catalyst to prepare a modified Mn-SCR catalyst. The effects of Mn loading and complex flue gas components (SO2, H2O and HCl) on the modified catalysts activity were investigated on a small fixed-bed experimental bench, respectively. As the Mn loading increases, the acid sites on the catalyst surface are significantly enhanced, the window of NO removal temperature is significantly widened, and the Hg(0) oxidation performance is nearly 100%. The optimal loading amount of Mn is 0.2(Mn/Ti, mol). When the Mn loading exceeds 0.2, the particles on the catalyst surface sinter, and the specific surface area decreases. However, little difference is observed in catalyst activity. When SO2 and H2O are present in the flue gas, dual-action catalyst activity can be significantly suppressed, but the effect of H2O on catalyst activity is greater than that of SO2. With the increase of the HCl concentration from 0 ppm to 50 ppm, the oxidation efficiency of Hg(0) and the removal efficiency of NO increased slightly.

Mn2O3/γ-Al2O3 catalysts synergistic double dielectric barrier discharge (DDBD) degradation of toluene, ethyl-acetate and acetone

Mn2O3/γ-Al2O3 catalysts was combined with double dielectric barrier discharge (DDBD) for degradation of acetone, toluene and ethyl acetate. Mn2O3/γ-Al2O3 catalysts with different Mn loading were synthesized by hydrothermal method. XRD, SEM, XPS and H2-TPR were applied to characterize the catalysts. Among the catalysts prepared, the Mn2O3/γ-Al2O3 catalysts with 5 wt% Mn loading presented the best performance in multicomponent VOCs degradation, which the highest removal efficiency (58.8% for acetone, 96.3% for toluene and 85.8% for ethyl acetate), the best carbon balance (87.5%) and CO2 selectivity (51.9%) were obtained at a specific input energy (SIE) of 700 J L−1. The formation of ozone was obviously inhibited with the introduction of Mn2O3/γ-Al2O3 catalysts. The higher Mn3+/Mn ratio, higher O2/O2− ratio and excellent low-temperature reducibility were beneficial for the VOCs degradation. Highly dispersed Mn2O3 crystals on the surface of γ-Al2O3 also might be an explanation for the improvement of VOCs degradation. According to the result of GC-MS, the variety of organic by-products gradually decreased with the increase of SIE, and the degradation mechanism of the mixed VOCs in plasma and on catalyst surface was discussed.

Mechanical and Microstructural Properties of Ti-V-Al High Temperature Shape Memory Alloy

The phase transformation, microstructural and mechanical properties of Ti-15V-2Al high temperature shape memory alloy produced with arc-melting method were investigated by DSC, XRD, SEM and high temperature micro-indenter system. The reverse martensitic transformation As starting and Af finishing temperatures of alloy were obtained to be 195 °C and 285 °C, respectively. In high temperature microindentation analysis, the alloy were subjected to indentation tests under 5000 mN load for three different temperatures (24 °C, 250 °C and 450 °C). The hardness and reduced elastic modulus values of the alloy at room temperature (24 °C ), that is, martensite structure, were found to be higher than the values at 450 °C, that is, austenite structure. The effect of temperature on superelasticity was examined and it was found that the superelasticity value of the alloy was higher at 450 °C compared to its value at 24 °C.

Application of portable X-ray and micro-X-ray fluorescence spectrometry to characterize alteration and mineralization within various gold deposits hosted in southern New Brunswick, Canada

New Brunswick hosts multiple types of gold deposits related to various stages of Appalachian orogenesis. Some of these structurally controlled deposits are considered intrusion-related; however, the majority have characteristics of orogenic deposits. The geochronology and genesis of the gold and antimony deposits in southern New Brunswick have been studied to varying degrees, but the relationship between mineralization and tectonism remains unresolved. This study involves the examination and comparison of auriferous quartz (-carbonate) veins associated with orogenic and intrusion-related gold mineralization of southern New Brunswick. The Belleisle Bay and Annidale groups (Annidale area) are host to mainly orogenic type gold mineralization, whereas in the Cookson and Mascarene groups (Clarence Stream area), gold mineralization is characterized as intrusion-related. For this study, the Devil Pike Brook deposit and Sheba Pit, East Scotch Settlement BP gold occurrences and the Bald Hill antimony deposit represent the Annidale area, whereas the South (Central and East subzones), George Murphy, Richard, and Jubilee zones represent gold mineralized areas in the Clarence Stream region.To facilitate the geochemical investigation of the various deposits and occurrences, an Olympus Vanta™ portable X-ray fluorescence spectrometer (pXRF) was used to rapidly analyse the composition of the different auriferous quartz (-carbonate) veins and characterize the alteration assemblages related to gold mineralization. The precision and accuracy of the pXRF data was monitored through QA/QC procedures, with the resulting corrected pXRF data undergoing principal component analysis (PCA) to fully interrogate the large data set.The PCA results highlight hydrothermal alteration and mineralization geochemical trends in the studied orogenic and intrusion-related gold deposits and occurrences. Some gold pathfinder elements reflect these different trends on the PC analysis on the studied samples. From the different PCs, various information about alteration and mineralization can be deduced. In Annidale area PC1 retrieves positive loadings of S, Cu, As, Pb, Zn, Fe, and Sb consistent with mineralization, PC2 displays positive loadings of Ca, Sr, Y, Mn and Ti, and PC3 extracts information about K, Rb, Ba, Zr, and Al consistent with alteration. In the Clarence Stream area, PC1 retrieved information about Al, K, Zr, Ba, Nb, Th and Rb consistent with alteration, PC2 displays positive loadings of As, Sb, Fe, Co, and S consistent with mineralization and PC3 extracts information about Zn, Pb, Mn, Fe, Cu, S and Si.Data obtained from the micro-X-Ray fluorescence–energy dispersive spectrometer (μ-XRF) analyses of the same sample suite concur with the alteration and mineralization characteristics identified using pXRF; these data indicate that chloritic and sericitic alteration with sulphides are associated with quartz (-carbonate) veins. The μ-XRF analysis is also helpful to further investigate sulphide and gold mineralization, as well as to locate potentially datable minerals, such as titanite, rutile, zircon, apatite, and monazite, in the gold-bearing quartz (-carbonate) veins; these data identified rutile and titanite in the Annidale samples and apatite in Clarence Stream samples that are being followed up geochronologically.

Preparation of Metal Modified onto Biochar from Hazardous Waste for Arsenic Removal.

Use of urban sludge, hospital sludge, and aquatic product sludge as a biochar adsorbent from wastewater treatment plants was investigated. Microwave carbonization was used to carbonize the sludge and then chemically activated at high temperatures to increase porosity and surface area. Effective of arsenic adsorption in water presents a newly designed metal doped to biochar. The biochar was characterized by scanning electron microscope (SEM) with energy dispersive X-ray (EDS), nitrogen adsorption/desorption isotherm analyzer (BET), thermo gravimetric analysis (TGA) and X-ray diffraction (XRD) analysis. Results display uniform pore sizes and high surface area (>490 m²g-1) of the biochar. Thence, urban sludge, hospital sludge, and aquatic product sludge can be used as carbon sources. The highest amount of Fe, Mn, and Ni loading onto the biochar was determined to be 8.0%, 6.0% and 10.0%, respectively. All biochar samples have arsenic adsorption capacities positively correlated with initial concentration. The corresponding removal efficiency of As(V) is 98% and As(III) is 84% at pH 3 with an adsorption capacity of 4.12 and 3.6 mg g-1, respectively. The adsorption capacity of As(V) and As(III) clearly decreased in the presence of PO₄3- (2.34 and 1.46 mg g-1, respectively). Due to competition for adsorption sites, the PO₄3- can effectively reduce arsenic adsorption. The arsenic species adsorption-desorption recycles on biochar are also discussed.

The effect of indentation temperature and load on mechanical characterization and transformation behavior of high temperature Ti-V-Al-Cu shape memory alloy

The effects of temperature and load on the indentation-induced mechanical characterization of the Ti-V-Al-Cu alloy were investigated. Also, the effects of heating/cooling rate and thermal cycle on the transformation temperatures were examined. Thermally-induced reverse martensite phase transformation was detected from α” martensite phase to β austenite phase during heating. Transformation temperatures decreased with the heating rate and thermal cycles. High temperature microindentation tests were conducted at both 450 °C (>As) and room temperature (24 °C) at four different loads to determine indentation-induced mechanical properties and deformation behaviors. The deformation mechanism of the Ti-V-Al-Cu alloy at 450 °C was found to involve the stress-induced martensite transformation associated with superelasticity and partially causing transformation from β phase to α” phase. The superelastic and total recoverable strains are 48% and 62% at 8000 mN load for 450 °C and are the highest values obtained for this study. The results show that the effect of load on the deformation mechanism of the same Ti-V-Al-Cu alloy at different temperatures is different and positively affects elastic recovery at 450 °C while causing plastic deformation at room temperature.

Geochemistry of natural acid rock drainage in the Judith Mountains, Montana, part 2: Seasonal and spatial trends in Chicago Gulch

Three streams radially draining Red Mountain, a prominent peak in the Judith Mountains of central Montana, are naturally acidic in their headwaters and experience a rise in pH as they transition from hydrothermally altered quartz monzonite to sedimentary bedrock in their lower reaches. A previous study (Williams et al., 2015) examined the geochemistry of two of these streams, Armells Creek and Collar Gulch, using detailed synoptic sampling with continuous tracer-injection. Here we present results of two synoptic sampling events in the third stream, Chicago Gulch. Data are compared between the three watersheds, and estimates of solute flux (load divided by watershed area) are presented.Filtered and unfiltered metal concentrations and loads are quantified with distance downstream in Chicago Gulch under low-flow (August) and high-flow (May) conditions. Headwater streams in the watershed have pH < 4 and extensive deposits of ferricrete and Fe-bog deposits. Weakly acidic springs (pH > 4) contain >10 mg/L of Fe2+ which quickly oxidizes and precipitates as hydrous ferric oxide (HFO), releasing protons that lower the pH of the stream. Geochemical modeling suggests the actively forming HFO is a mix of schwertmannite and ferrihydrite, both of which are slowly converting to goethite which cements the ferricrete deposits. White, hydrous aluminum oxide (HAO) flocs form where stream pH transitions from <5 to >5, and a comparison of filtered and unfiltered samples indicates strong partitioning of Cu and Pb into the suspended particles. Dissolved loads of Zn, Cd, Mn, and Tl (thallium) diminish slightly in the lower reaches of Chicago Gulch where pH rises above 7.All water samples collected in the upper reaches of Chicago Gulch exceed the US-EPA water quality standards for protection of aquatic life for Pb, Cd, Zn, and Cu, and human health standards for Tl. Lead concentrations are especially high in the headwaters of Chicago Gulch, indicating the possible presence of an unmined Pb-sulfide deposit. Estimates of the load of dissolved sulfate at baseflow conditions in each stream on Red Mountain, normalized to their respective surface areas of hydrothermally altered bedrock, are remarkably similar, and indicate a steady state pyrite oxidation rate of 11.9 mol FeS2/h/km2. Prediction of pre-modern pH using the methods of Nimick et al. (2009) indicates that the current pH regimes of all three streams draining Red Mountain are broadly similar to conditions when ancient ferricretes were deposited. Because the Judith Mountains were never glaciated in the Pleistocene, it is possible that similar hydro-geochemical conditions have existed in the area for 10's to 100's of thousands of years.

A Gas-Phase Migration Strategy to Synthesize Atomically Dispersed Mn-N-C Catalysts for Zn-Air Batteries.

Mn and N codoped carbon materials are proposed as one of the most promising catalysts for the oxygen reduction reaction (ORR) but still confront a lot of challenges to replace Pt. Herein, a novel gas-phase migration strategy is developed for the scale synthesis of atomically dispersed Mn and N codoped carbon materials (g-SA-Mn) as highly effective ORR catalysts. Porous zeolitic imidazolate frameworks serve as the appropriate support for the trapping and anchoring of Mn-containing gaseous species and the synchronous high-temperature pyrolysis process results in the generation of atomically dispersed Mn-Nx active sites. Compared to the traditional liquid phase synthesis method, this unique strategy significantly increases the Mn loading and enables homogeneous dispersion of Mn atoms to promote the exposure of Mn-Nx active sites. The developed g-SA-Mn-900 catalyst exhibits excellent ORR performance in the alkaline media, including a high half-wave potential (0.90 V vs reversible hydrogen electrode), satisfactory durability, and good catalytic selectivity. In the practical application, the Zn-air battery assembled with g-SA-Mn-900 catalysts shows high power density and prominent durability during the discharge process, outperforming the commercial Pt/C benchmark. Such a gas-phase synthetic methodology offers an appealing and instructive guide for the logical synthesis of atomically dispersed catalysts.

Monolithic composites with geometry controlled by polymeric 3D printed templates: Characterization and catalytic performance in OCM

Designed in computer-aided design (CAD) software and three-dimensional (3D) printed in Digital Light Processing (DLP) technology polymeric templates were applied to control in micron-scale macroporosity, shape and size of Mn-containing monolithic composites. The monoliths with 0.5, 1, 2, 5 and 10 wt% of Mn were characterised by X-ray fluorescence (XRF), X-ray diffraction (XRD), diffuse reflectance UV–Vis spectroscopy (UV–Vis DRS), temperature-programmed reduction with hydrogen (H2-TPR), scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS) and X-ray photoelectron spectroscopy (XPS) techniques and tested in oxidative coupling of methane (OCM). The effect of Mn loading as well as an influence of channels size and their density on the catalytic performance in OCM was carefully investigated. In a series of monoliths containing 35 channels with different diameters (0.4, 0.6, 0.8 and 1.0 mm) the maximum conversion of methane vs. selectivity to C2+ hydrocarbons was observed for the samples with channels size 0.6 and 0.8 mm. Moreover, modification of the channels density had also a beneficial effect on the catalytic performance in OCM. Yield of C2+ grew with the increase in the number of channels in the monolith.

MnOx Supported on Hierarchical SAPO-34 for the Low-Temperature Selective Catalytic Reduction of NO with NH3: Catalytic Activity and SO2 Resistance

The ethanol dispersion method was employed to synthesize a series of MnOx/SAPO-34 catalysts using SAPO-34 with the hierarchical pore structure as the zeolite carrier, which were prepared by facile acid treatment with citric acid. Physicochemical properties of catalysts were characterized by XRD, XPS, BET, TEM, NH3-TPD, SEM, FT-IR, Py-IR, H2-TRP and TG/DTG. NH3-SCR performances of the hierarchical MnOx/SAPO-34 catalysts were evaluated at low temperatures. Results show that citric acid etching solution at a concentration of 0.1 mol/L yielded a hierarchical MnOx/SAPO-34-0.1 catalyst with ca.15 wt.% Mn loading, exhibiting optimal catalytic activity and SO2 tolerance at low temperatures. Almost 100% NO conversion and over 90% N2 selectivity at 120 °C under a gas hourly space velocity (GHSV) of 40,000 h−1 could be obtained over this sample. Furthermore, the NO conversion was still higher than 65% when 100 ppm SO2 was introduced to the reaction gas for 4 h. These could be primarily attributed to the large specific surface area, high surface acidity concentration and abundant chemisorbed oxygen species provided by the hierarchical pore structure, which could also increase the mass transfer of the reaction gas. This finding suggests that the NH3-SCR activity and SO2 poisoning tolerance of hierarchical MnOx/SAPO-34 catalysts at low temperatures can be improved by controlling the morphology of the catalysts, which might supply a rational strategy for the design and synthesis of Mn-based SCR catalysts.

Application of a blast furnace slag carrier catalyst in flue gas denitration and sulfur resistance.

It is an urgent need to develop a new catalyst with high efficiency and low cost. In the present study, we successfully prepared bimetallic-supported denitration catalysts using the blast furnace slag as the main material and calcium bentonite as the binder. The as-prepared catalyst was characterized via X-ray diffraction analysis (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). Besides, the mechanism of denitration was further determined with the help of the denitration and sulfur resistance of the catalyst. The results indicated that when the Mn load was 5%, and the second metal reactive component was loaded at 3%, Mn–Cu/GGBS (catalyst prepared by loading Mn and Cu on the blast furnace slag) had the best effects on low temperature denitration. Moreover, the conversion rate of NO was up to 97%, and it possessed the capability of specific sulfur resistance; when the third metal reactive component, Ce, was introduced with 1% load, the sulfur resistance of the Mn–Cu–Ce/GGBS (catalyst prepared by loading Mn, Cu, and Ce on the blast furnace slag) catalyst was further improved compared with that of the Mn–Cu/GGBS catalyst.

High loading of Mn(ii)-metalated porphyrin in a MOF for photocatalytic CO2 reduction in gas-solid conditions.

A high loading of Mn(ii)-metalated porphyrin was achievable in a 2D porphyrin-based Mn-MOF induced by an ionic liquid. The excellent stability, sufficient redox potential, atomically dispersed porphyrin Mn(ii) sites, desired CO2 affinity, high visible light-harvesting and efficient charge separation, endow this MOF with the overall photocatalytic conversion of CO2 to CH4 in gas-solid conditions.