Showing papers on "Mixed oxide published in 2018"
TL;DR: In this paper, a spinel-structured Co 7 Mn 3 O 4 4.5 phase and higher surface area was used for the selective catalytic reduction (SCR) of NO x with ammonia.
Abstract: A highly efficient catalyst of a Co a Mn b O x mixed oxide prepared by the co-precipitation method was developed for the selective catalytic reduction (SCR) of NO x with ammonia. With an increase in the Mn content, the catalytic activity of the Co a Mn b O x mixed oxide exhibited a volcano-type tendency, and when Co/Mn molar ratio reached 7:3 (Co 7 Mn 3 O x ), the operation temperature for achieving >80% NO x conversion was 170 °C (116–285 °C window). The formation of spinel structured MnCo 2 O 4 is highly important, and the presence of the spinel structure in Co 7 Mn 3 O x contributes to the increase in active sites and thermal stability and promotes SO 2 and/or H 2 O resistance. In comparison with MnO x or CoO x alone, the Co a Mn b O x catalysts possess improved redox properties and more surface acid sites due to synergistic effects between the Co and Mn species. Among the Co a Mn b O x catalysts with different Co/Mn molar ratios, a higher NH 3 and NO + O 2 adsorption ability was found for the Co 7 Mn 3 O x catalyst, originating from its MnCo 2 O 4.5 phase and higher surface area, which leads to the higher activity of the Co 7 Mn 3 O x catalyst. In situ DRIFTs indicated that bridging nitrate and bidentate nitrate are the intermediate species in the NH 3 -SCR reaction, and the high NO adsorption ability and improved redox properties of the Co 7 Mn 3 O x catalyst are beneficial for the formation of nitrate species on the catalyst surface. Furthermore, NH 3 species adsorbed at Lewis acid sites taken part in SCR reaction, while the reactivity of NH 3 species adsorbed at Bronsted acid was not definitized.
178 citations
TL;DR: In this article, the authors demonstrate that the AQY during overall water splitting by rhCrOx/STO:Al is improved by 20% (to 69% at 365 nm) by coloading of molybdenum oxide (MoOy, 0.03 wt % as Mo) followed by calcination.
Abstract: Al-doped SrTiO3 loaded with a rhodium–chromium mixed oxide (RhCrOx/STO:Al) efficiently promotes photocatalytic overall water splitting with an apparent quantum yield (AQY) of 56% under 365 nm ultraviolet (UV) light. Further increasing this AQY is of vital importance, because this value determines the maximum solar to hydrogen energy conversion efficiency that can be achieved. Herein, we demonstrate that the AQY during overall water splitting by RhCrOx/STO:Al is improved by 20% (to 69% at 365 nm) by coloading of molybdenum oxide (MoOy, 0.03 wt % as Mo) followed by calcination. Reductively photodeposited MoOy modifies the chemical state of the RhCrOx cocatalyst and likely promotes photocatalytic H2 evolution, whereas MoOy loaded onto STO:Al does not catalyze either photocatalytic H2 or O2 evolution. The present study indicates a means of further enhancing the water-splitting activity of highly efficient cocatalyst/photocatalyst composites by loading small amounts of promoters in a facile manner.
160 citations
TL;DR: In this paper, a series of Ti-Nb binary oxide were synthesized by co-precipitation as supports to prepare Cu/Ti 2 Nb mixed oxide catalysts through wetness impregnation.
Abstract: A series of Ti-Nb binary oxide were synthesized by co-precipitation as supports to prepare Cu/Ti-Nb mixed oxide catalysts through wetness impregnation. The novel catalyst 0.8%Cu/Ti 2 NbO x exhibited an excellent catalytic activity and N 2 selectivity with a broad operation temperature (250–425 °C) under a gas hourly space velocity (GHSV) of 177,000 h −1 for the selective catalytic reduction of NO x with NH 3 . A series of analytical techniques including high resolution transmission electron microscopy (HRTEM), N 2 -physisorption, X-ray diffraction (XRD), Laser Raman spectra (LRS), X-ray photoelectron spectroscopy (XPS), electron paramagnetic resonance (EPR), NH 3 temperature-programmed desorption (NH 3 -TPD), H 2 temperature-programmed reduction (H 2 -TPR) and in situ diffuse reflectance infrared Fourier transform spectroscopy (in situ DRIFTS) were used to investigate the correlations among catalyst structure, surface properties and catalytic performance. For the support Ti 2 NbO x , the specific surface area was larger than that of TiO 2 , promoting the high dispersion of the active component. Also, the surface acid sites were increased by addition of niobium oxide species and the redox capability of the support was enhanced by doping copper species. Moreover, the introduction of copper species effectively enhanced the catalytic performance within 225–400 °C. The copper species mainly existed as isolated Cu 2+ and non-isolated Cu + and the isolated Cu 2+ ions played a significant role in the high NH 3 -SCR performance over 0.8%Cu/Ti 2 NbO x catalyst. Hydrothermal aging treatment experiment demonstrated that 0.8%Cu/Ti 2 NbO x catalyst had an excellent hydrothermal stability. In addition, water vapor or/and SO 2 had a slightly reversible inhibition influence on the catalytic performance over 0.8%Cu/Ti 2 NbO x , indicating that it was a promising candidate for NH 3 -SCR catalyst in the future practical application. The reaction pathway over 0.8%Cu/Ti 2 NbO x catalyst followed both Eley-Rideal mechanism and Langmuir-Hinshelwood mechanism at 225 °C.
134 citations
TL;DR: In this article, a low-temperature NH3-SCR catalyst with a chemical composition of CuwMnyTi1-yOx was prepared from layered double hydroxides precursors for the first time.
Abstract: A new type of low-temperature NH3-SCR catalyst with a chemical composition of CuwMnyTi1-yOx was prepared from layered double hydroxides precursors for the first time. The purpose of this novel design is to improve the De-NOx efficiency and SO2 resistance of Mn-based catalysts. The Cu1Mn0.5Ti0.5Ox catalyst achieved a NOx conversion as high as 90% at 200 °C, which is much higher than that of the control catalysts Cu-Mn/TiO2 (86.1%) and Mn/TiO2 (80.7%). The properties of catalysts were characterized in detail using a series of physico-chemical techniques including XRD, BET, FTIR, SEM, TEM, H2-TPR, NH3-TPD, TGA, and XPS analyses. The excellent catalytic performance of Cu1Mn0.5Ti0.5Ox catalyst can be associated with its higher specific surface area and surface acidity, and more active MnO2 and CuO species. Besides, when copper oxide is introduced, the catalysts showed significant resistance to 100 ppm SO2 and 5% H2O. Finally, the poisoning mechanism and the regenerability of Cu1Mn0.5Ti0.5Ox catalyst was proposed. In short, the newly designed Cu1Mn0.5Ti0.5Ox catalyst was found to have higher catalytic activity and excellent SO2 and H2O resistance compared to the control catalysts of Cu-Mn/TiO2 and Mn/TiO2.
121 citations
TL;DR: In this article, Ru nanoparticles with a mean size of 4.4 nm were used as a support to activate and oxidize the 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA) without addition of any base additives.
110 citations
TL;DR: In this paper, hydrotalcite-derived catalysts promoted with Zr species were prepared via co-precipitation method, resulting in materials with various Zr loading.
Abstract: Hydrotalcite-derived catalysts promoted with Zr species were prepared via co-precipitation method, resulting in materials with various Zr loading. Physicochemical properties of catalysts precursors and final catalysts were investigated via XRF, XRD, low temperature N2 sorption, H2-TPR, CO2-TPD, TG, SEM and TEM techniques. So characterized catalysts were subsequently tested in the dry methane reforming reaction at 550 °C. Zr-loading introduced into brucite-like layers influenced the process of thermal decomposition of HTs and, as a result, their properties and performance in DRM. Although Zr promotion decreased activity, it strongly increased the stability and selectivity of the catalysts. The catalyst with Zr species present in the framework of periclase-like mixed oxide exhibited high resistance to coking due to the rearrangement of Ni particles upon DRM reaction.
104 citations
TL;DR: A series of MgO supported bimetallic Fe-Mo catalysts with various Fe:Mo weight ratios (such as 50:0, 45:5, 40:10, 30:20, 20:30 and 10:40, respectively) have been prepared and evaluated for production of carbon nanomaterials (CNMs) via catalytic pyrolysis of low-density polyethylene (LDPE) plastic waste as discussed by the authors.
84 citations
TL;DR: The defect induced mesoporous metal oxide nanocomposite is an outstanding candidate for application as redox active material in electrochemical biosensors as discussed by the authors, which is an extraordinary sensitive and selective non-enzymatic glucose sensor has been demonstrated based on the electrochemically highly stable NiO-TiO2 mixed oxide comprising the defect induced mesh with Ni2+ and Ni3+ ions scattered on the surface.
Abstract: An extraordinary sensitive and selective non-enzymatic glucose sensor has been demonstrated based on the electrochemically highly stable NiO-TiO2 mixed oxide comprising the defect induced mesoporous TiO2 nanoparticles with Ni2+ and Ni3+ ions scattered on the surface. The defects on TiO2 nanoparticles have been successfully introduced using NiO to investigate the interfacial properties between NiO and TiO2. This defect induced interfacial behavior was characterized using X-ray diffraction, X-ray photoelectron spectroscopy and high-resolution transmission electron microscopy analyses. The obtained mixed oxide NiO-TiO2 nanocomposite dispersion was drop casted on glassy carbon electrode to form a NiO-TiO2/GCE modified electrode for non-enzymatic glucose sensor. The defects along with high surface area of mixed oxide enabled excellent electrocatalytic activity for glucose oxidation with sensitivity of 24.85 μA mM−1 cm−2 and detection limit of 0.7 μM (S/N = 3). The Ni ions scattered on the surface of TiO2 nanoparticles, enabling effective charge transfer process, circumventing the agglomeration during prolonged detection, and resulting the unprecedented long-term stability and sensitivity. Thus, this defect induced mesoporous metal oxide nanocomposite is an outstanding candidate for application as redox active material in electrochemical biosensors.
83 citations
TL;DR: In this article, a double charge transfer mechanism was proposed for the separation and transfer of photogenerated charge carriers in the photocatalysts, which is mainly attributed to the enhanced visible light absorption, efficient charge carriers separation, and the loading of α-Fe2O3 on Cu2O.
82 citations
TL;DR: In this article, the influence of surface properties of metal oxides on the type of reactive oxygen species (ROS) formed in contact with hydrogen peroxide, and to determine the effect of zinc addition to niobium pentoxide and its activity in methylene blue degradation was investigated.
Abstract: The aim of this work was to investigate the influence of surface properties of metal oxides (Nb2O5, ZnO and ZnNb2O6) on the type of reactive oxygen species (ROS) formed in contact with hydrogen peroxide, and to determine the effect of zinc addition to niobium pentoxide on the type of ROS formed and its activity in methylene blue degradation. The structure and surface properties of materials synthesized were characterized by nitrogen adsorption, XRD, XPS, SEM, SEM-EDX, DR UV–vis and FTIR techniques. The ability of metal oxides to generate superoxo and peroxo species upon treatment with H2O2 was documented and discussed in respect to the type of metal oxide used. It was found that the distortion of NbO6 species in bimetallic oxide influenced the interaction of this mixed oxide with hydrogen peroxide. The oxidative properties of reactive oxygen species formed on the surface of metal oxides were tested in degradation of methylene blue. The activity of niobium(V) oxide in this process was much higher than that of mixed oxide and ZnO. In order to identify the reaction pathways on the basis of determination of the reaction intermediates, the reaction mixtures were analyzed by ESI–MS. On the basis of the results obtained the mechanism of the dye degradation was discussed.
81 citations
TL;DR: In this paper, an equimolar NiAlOx benchmark catalyst was synthesized and modified by doping with Fe or Mn up to 10% of promoter by co-precipitation at constant pH 9.
Abstract: The methanation reaction of CO2 is in discussion to be a sustainable pathway to address future questions arising from limited primary energy feedstock and the accumulation of CO2 in the atmosphere. Therefore, the development of highly active and thermostable catalysts for this reaction is an indispensable matter of research. For this reason, an equimolar NiAlOx benchmark catalyst (44 wt.% Ni loading) was synthesized and modified by doping with Fe or Mn up to 10 wt.% of promoter by co-precipitation at constant pH 9. Their activity and stability performances in the CO2 methanation reaction were evaluated by comparing the conversion versus temperature characteristics before and after an aging period of 32 h at 500 °C. Material characterization studies comprising BET, XRD, in situ IR spectroscopy, XPS, H2 and CO2 chemisorption, and EPR/FMR contributed to derive structure-activity relationships and to obtain a deeper understanding of the catalytic behavior. Promotion with Mn led to a significant enhancement of the catalytic activity. This is assumed to be caused by a higher density of medium basic sites and an enhanced CO2 adsorption capacity on the activated catalyst related to interactions between Mn oxide species and the mixed oxide phase, in combination with a stabilization of the Ni surface area at moderate Mn loadings. Promotion with Fe increased the thermal stability of the catalyst, which is attributed to the formation of a Ni-Fe alloy during catalyst activation. For both phenomena, the optimum molar Ni to promoter ratio for co-precipitated catalysts was found to be around 5.
TL;DR: In this article, the effect of the ZrO2 phase on CO2-to-methanol hydrogenation was examined using a simple impregnation method and the results showed that the high dispersion of Cu species and weak adsorption of methanol led to high activity and selectivity in CO2 to methanol conversion.
Abstract: We prepared Cu/a-ZrO2 (a-ZrO2: amorphous ZrO2), Cu/m-ZrO2 (m-ZrO2: monoclinic ZrO2), Cu/a-ZrO2/KIT-6, and Cu/t-ZrO2/KIT-6 (t-ZrO2: tetragonal ZrO2) by a simple impregnation method and examined the effect of the ZrO2 phase on CO2-to-methanol hydrogenation. We discovered a-ZrO2-containing catalysts with high activity and selectivity in CO2-to-methanol hydrogenation. Next, we focused on Cu species formation on the above-described catalysts. While pure CuO was observed on Cu/m-ZrO2 and Cu/t-ZrO2/KIT-6, copper-zirconium mixed oxide (CuxZryOz), not pure CuO, was formed on Cu/a-ZrO2 and Cu/a-ZrO2/KIT-6, as evidenced by X-ray absorption spectroscopy (XAS) and the powder color. After reducing a-ZrO2-containing catalysts with H2 at 300 °C, we observed highly dispersed Cu nanoparticles in close contact with a-ZrO2 (or CuxZryOz). In addition, methanol vapor sorption revealed that methanol adsorbed more weakly on a-ZrO2 than on m-ZrO2. Therefore, the high dispersion of Cu species and weak adsorption of methanol led to...
TL;DR: In this paper, an ultrasonic-assisted impregnation method was employed for simultaneous nitrogen monoxide (NO) reduction and elemental mercury (Hg0) oxidation under selective catalytic reduction (SCR) atmosphere with the presence of NH3.
TL;DR: In this paper, a template-free strategy for fabricating two-dimensional mesoporous mixed oxide nanosheets, such as metal cobaltites (MCo2O4, M = Ni, Zn) through the self-deconstruction/reconstruction of highly uniform Co-based metal glycerate nanospheres into 2D Co-briches, induced by the so-called water treatment process at room temperature followed by their calcination in air at 260 °C.
Abstract: In this work, we propose a general template-free strategy for fabricating two-dimensional mesoporous mixed oxide nanosheets, such as metal cobaltites (MCo2O4, M = Ni, Zn) through the self-deconstruction/reconstruction of highly uniform Co-based metal glycerate nanospheres into 2D Co-based metal glycerate/hydroxide nanosheets, induced by the so-called “water treatment” process at room temperature followed by their calcination in air at 260 °C. The proposed ‘self-deconstruction/reconstruction’ strategy is highly advantageous as the resulting 2D metal cobaltite nanosheets possess very high surface areas (150–200 m2 g−1) and mesoporous features with narrow pore size distribution. In addition, our proposed method also enables the crystallization temperature to achieve pure metal cobaltite phase from the precursor phase to be lowered by 50 °C. Using the 2D mesoporous NiCo2O4 nanosheets as a representative sample, we found that they exhibit 6–20 times higher specific capacitance and greatly enhanced capacitance retention compared to the NiCo2O4 nanospheres achieved through the direct calcination of the Ni–Co glycerate nanospheres. This highlights another advantage of the proposed strategy for enhancing the electrochemical performance of the mixed oxide products for supercapacitor applications. Furthermore, the asymmetric supercapacitor (ASC) assembled using the 2D NiCo2O4 nanosheets//graphene oxide (GO) exhibits a maximum energy density of 38.53 W h kg−1, while also showing a high capacitance retention of 91% after 2000 cycles at 5 A g−1. It is expected that the proposed general method may be extended to other transition metal elements for creating 2D mixed oxide nanosheets with enhanced surface areas and improved electrochemical performance.
TL;DR: In this article, the authors reported that the photocatalytic activity of the prepared materials has been evaluated for the photodegradation of methylene blue (MB), and the concentration of MB was monitored by UV-Vis spectroscopy.
Abstract: TiO2-SiO2 mixed oxides have been prepared by the sol–gel technique from tetrabutyl orthotitanate and tetraethyl orthosilicate. The prepared materials were characterized by x-ray diffraction, scanning electron microscopy, energy dispersive x-ray spectroscopy, nitrogen physisorption, Fourier-transform infrared spectroscopy (FT-IR) and x-ray photoelectron spectroscopy (XPS). The results indicate that the TiO2-SiO2 mixed oxides have a large surface area and a nanoscale size. FT-IR spectra show that Ti atoms are bonded to silica by oxygen bridging atoms in Ti-O-Si bonds. The titanium valence states in TiO2-SiO2 mixed oxides were investigated by XPS, and their spectra report the presence of Ti2+ and Ti3+ cations for high silica concentration, suggesting the formation of oxygen vacancies. The photocatalytic activity of the prepared materials has been evaluated for the photodegradation of methylene blue (MB). The mixed oxides were activated by means of a UV light source, and the concentration of MB was monitored by UV–Vis spectroscopy. The synthesized TiO2-SiO2 shows significantly higher MB removal efficiency in comparison with that of the commercial TiO2 Degussa, P25. In this paper, we observed three valence states of titanium: Ti4+, Ti3+ and Ti2+ in TiO2-SiO2 40%. This issue has not yet been reported. XPS analysis show that the content of Ti2+ and Ti3+ amounts to 25.26 at.% and 13.08 at.%, respectively, while the concentration of Ti4+ is 61.72 at.%, much lower than in the TiO2-SiO2 9% sample. This behavior is explained observing that in TiO2-SiO2 40%, Ti4+ is reduced to Ti3+ and Ti2+ to a larger extent with respect to TiO2-SiO2 9%.
TL;DR: In this paper, the results showed that surface functional groups were increased after nitric acid treatment and abundant oxygen groups were observed on semi-coke surface, which were considered to be beneficial for the gas adsorption.
Abstract: Mn–Ce mixed oxide was loaded onto activated semi-coke (ASC) via impregnation method and the low temperature selective catalytic reduction (SCR) of NO with NH3 was investigated. The NO conversion and NO oxidation rates were both influenced by the ratios of Ce/(Mn + Ce), and Mn–Ce(0.3)/ASC with loading 5% (mass ratio) Mn–Ce oxides performed the highest catalytic conversion rate of 96.6% and NO oxidation rate of 18.4% at 250 °C and GHSV = 6000 h−1. The changes of physical properties, microstructure, functional groups, crystal structure, surface atomic state, redox property and acid strength for the catalysts were characterized by BET, SEM, FT-IR, XRD, XPS, H2-TPR and NH3-TPD. The results showed that surface functional groups were increased after nitric acid treatment and abundant oxygen groups were observed on semi-coke surface, which were considered to be beneficial for the gas adsorption. Ce doping could raise the Mn4+/Mnx+ rate which played a vital role in catalytic reaction, enhancing the amount of weak and strong acid sites, increasing oxygen vacancies and accelerating the molecular oxygen turning into reactive oxygen species, which could enhance the NO oxidation activity thus contributed to the denitration efficiency.
TL;DR: In this article, the authors compared the catalytic activity of nanostructured ceria-praseodymia impregnated with Pt nanoparticles stabilized by n -octylsilane (Pt/Ce50Pr50-NP), with pure ceria nanoparticles (Ce-NP, ceria praseodym, and Pt on ceria), and found that the Pt/ceria and Ce-Pr mixed oxide are effective towards CO, NO and soot oxidations, as well as for the NO x -assisted soot oxidation.
Abstract: This work compares the catalytic activity of nanostructured ceria-praseodymia impregnated with Pt nanoparticles stabilized by n -octylsilane (Pt/Ce50Pr50-NP), with pure ceria nanoparticles (Ce-NP), ceria-praseodymia (Ce50Pr50-NP) and Pt on ceria (Pt/Ce-NP). The idea behind these structures stems from the fact that both Pt/ceria and Ce-Pr mixed oxide are effective towards CO, NO and soot oxidations, as well as for the NO x -assisted soot oxidation. The oxide supports have been prepared via a hydrothermal synthesis. Catalytic activity tests have shown the effectiveness of Ce50Pr50-NP towards the NO x -assisted soot oxidation. The intrinsic activity of this material is even higher than the Pt/Ce-NP counterpart. This finding seems related to the adsorption of NO 2 onto ceria-praseodymia. The addition of Pt on the Ce50Pr50-NP surface appears unnecessary as the effect of Pr on the catalytic activity prevails. The samples have also been thermally aged and their catalytic performances have been compared. A smaller decrease in activity has been observed for Ce50Pr50-NP, compared to Ce-NP, and it has been linked to the material’s persistent adsorptive properties. The deposited Pt nanoparticles on the surface of Ce50Pr50-NP, however, have suffered from sintering after the thermal aging, and therefore both aged Pt/Ce50Pr50-NP and Ce50Pr50-NP have comparable catalytic performances.
TL;DR: In this paper, Alumina-supported platinum catalysts have been modified with silicon oxide thin films grown using atomic layer deposition (ALD) in order to tune acid base and electronic properties of the oxide, and their performance has been tested for the hydrogenation of cinnamaldehyde.
Abstract: Alumina-supported platinum catalysts have been modified with silicon oxide thin films grown using atomic layer deposition (ALD) in order to tune the acid–base and electronic properties of the oxide, and their performance has been tested for the hydrogenation of cinnamaldehyde. It was found that the silica layers greatly increase the stability of the platinum nanoparticles, preventing their sintering during high-temperature calcinations without affecting access to the metal surface in any significant way; the extent of CO adsorption, measured by infrared absorption spectroscopy was found to decrease by only one-third after 6 SiO2 ALD cycles. Additional Bronsted and Lewis acid sites were created upon the deposition of submonolayer coverages of silicon oxide, as probed via pyridine adsorption. The addition of the silicon oxide thin films reduced the overall activity of these catalysts but also increased their selectivity toward the production of the unsaturated alcohol. In addition, both turnover frequencies...
TL;DR: In this article, a manganese-iron mixed oxide material with a molar ratio of 0.77:0.23 was evaluated for coal combustion by means of chemical looping processes.
TL;DR: A new type of low-temperature selective catalytic reduction (SCR) catalyst, CuyMnzAl1-zOx, derived from layered double hydroxides is presented, and by tuning the Cu/Mn/Al ratio, the optimal catalyst Cu2Mn0.5Al 0.5Ox is not only more active at low temperatures, but is also relatively more robust in the presence of SO2 and H2O.
Abstract: A new type of low-temperature selective catalytic reduction (SCR) catalyst, CuyMnzAl1−zOx, derived from layered double hydroxides is presented in this contribution. By tuning the Cu/Mn/Al ratio, the optimal catalyst Cu2Mn0.5Al0.5Ox resulted in a NOx conversion of 91.2% at 150 °C, which is much higher than that of all other control catalysts, Cu2AlOx (71.1%), Cu–Mn/γ-Al2O3 (65.23%), and Mn/γ-Al2O3 (59.32%). All samples were characterized in detail using various physico-chemical techniques including XRD, BET, FTIR, TEM, H2-TPR, NH3-TPD, and XPS analyses, and the results revealed that the superior catalytic performance of the Cu2Mn0.5Al0.5Ox catalyst can be attributed to its high specific surface area, high reducibility of MnO2 and CuO species, abundance of surface acid sites, and the good dispersion of MnO2 and CuO species. FTIR analyses of pyridine adsorbed samples revealed that the catalytic activity is proportional to the amount of Lewis acid sites. Cu2Mn0.5Al0.5Ox also showed much higher resistance to 100 ppm SO2 and 5% H2O than the control catalysts. The poisoning mechanism and the regenerability of the Cu2Mn0.5Al0.5Ox catalyst was also investigated. In all, compared with the control catalysts of Cu2AlOx, Cu–Mn/γ-Al2O3, and Mn/γ-Al2O3, the newly designed Cu2Mn0.5Al0.5Ox catalyst is not only more active at low temperatures (100–250 °C), but is also relatively more robust in the presence of SO2 and H2O.
TL;DR: In this paper, thin films of uranium cerium mixed oxides have been prepared by DC sputtering and characterized by X-ray photoelectron spectroscopy (XPS) for reduction and oxidation properties.
TL;DR: The high activity and low cost of the Co-Mn mixed-oxide catalysts prepared by solid-state grinding make it promising for industrial application for the manufacturing of polyethylene furanoate, a bioreplacement for polyethylenes terephthalate, from sustainable bioresources.
Abstract: A highly active and inexpensive Co-Mn mixed-oxide catalyst was prepared and used for selective oxidation of 5-hydroxymethylfurfural (HMF) into 2, 5-furandicarboxylic acid (FDCA). Co-Mn mixed-oxide catalysts with different Co/Mn molar ratios were prepared through a simple solid-state grinding method-a low-cost and green catalyst preparation method. The activity of these catalysts was evaluated for selective aerobic oxidation of HMF into FDCA in water. Excellent HMF conversion (99 %) and FDCA yield (95 % ) were obtained under the best reaction conditions (i.e., 120 °C, 5 h, Co-Mn mixed-oxide catalyst with a Co/Mn molar ratio of 0.25 calcined at 300 °C (Co-Mn-0.25) and 1 MPa O2 ). The catalyst could be reused five times without a significant decrease in activity. The results demonstrated that the catalytic activity and selectivity of the Co-Mn mixed-oxide catalysts prepared through solid-state grinding were superior to the same Co-Mn catalyst prepared through a conventional coprecipitation method. The high catalytic activity of the Co-Mn-0.25 catalyst was attributed to its high lattice oxygen mobility and the presence of different valence states of manganese. The high activity and low cost of the Co-Mn mixed-oxide catalysts prepared by solid-state grinding make it promising for industrial application for the manufacturing of polyethylene furanoate, a bioreplacement for polyethylene terephthalate, from sustainable bioresources.
TL;DR: In this paper, a series of supported iron oxide based catalysts, Fe2O3 (15wt%)/MO2 (M = Zr, Ce, Ti and Si), synthesized by adsorption-equilibrium method, is investigated for sulfuric acid decomposition reaction.
TL;DR: In this paper, a series of Ni nano-catalysts supported on Al2O3 and MgO were prepared through the co-precipitation technique, and the effects of the Al/Mg ratio on physicochemical characteristics of Ni/Al 2O3 Mg O catalysts were examined.
TL;DR: In this paper, the adsorption of CO 2 on Co, Fe and Ni mixed oxides derived from a commercial hydrotalcite and calcined at 500°C was measured at several temperatures and pressures.
TL;DR: In this paper, a rapid solvent-free ball-milling method was developed to prepare a hydrophobic hydrotalcite supported Cu-Mn mixed oxide catalyst (CuMn/HT), which exhibited high catalytic activity and recyclability towards the aerobic synthesis of 2-acylbenzothiazoles and quinoxalines.
TL;DR: A novel NH3-SCR catalyst Cu0.5Ox synthesized from layered double hydroxides with superior activity in a wide temperature range and improved SO2 and H2O resistance comparing to conventional doped Mn/γ-Al2O3 is reported.
TL;DR: In this article, spherical mixed oxides of Al2O3 and TiO2 supported molybdenum (Mo) catalysts were successfully prepared using a novel approach combining sol-gel and spray pyrolysis (SP) methods.
TL;DR: In this paper, a series of efficient and robust Cu-based mixed oxides were synthesized by a simple co-precipitation method and utilized for the production of glycerol carbonate (GC) via transesterification of glyricol with DMC.
TL;DR: In this article, the structural stability and electrocatalytic oxygen reduction reaction (ORR) of platinum nanoparticles on ruthenium-titanium mixed oxide (RTO) supports during electrochemical accelerated stress tests, mimicking fuel cell operating conditions were tracked using a variety of in situ techniques.
Abstract: Using a variety of in situ techniques, we tracked the structural stability and concomitantly the electrocatalytic oxygen reduction reaction (ORR) of platinum nanoparticles on ruthenium–titanium mixed oxide (RTO) supports during electrochemical accelerated stress tests, mimicking fuel cell operating conditions High-energy X-ray diffraction (HE-XRD) offered insights in the evolution of the morphology and structure of RTO-supported Pt nanoparticles during potential cycling The changes of the atomic composition were tracked in situ using scanning flow cell measurements coupled to inductively coupled plasma mass spectrometry (SFC-ICP-MS) We excluded Pt agglomeration, particle growth, dissolution, or detachment as cause for the observed losses in catalytic ORR activity Instead, we argue that Pt surface poisoning is the most likely cause of the observed catalytic rate decrease Data suggest that the gradual growth of a thin oxide layer on the Pt nanoparticles due to strong metal–support interaction (SMSI) is