scholarly journals Reduction of NOx by H2 on WOx-Promoted Pt/Al2O3/SiO2 Catalysts Under O2-Rich Conditions

2021 ◽  
Author(s):  
Enno Eßer ◽  
Daniel Schröder ◽  
Anna V. Nartova ◽  
Aleksey M. Dmitrachkov ◽  
Sven Kureti
Keyword(s):  
Photoelectron Spectroscopy ◽  
Laser Raman Spectroscopy ◽  
Promoting Effect ◽  
X Ray ◽  
Laser Raman ◽  
Supported Pt Catalysts ◽  
Metal Support Interaction ◽  
Metal Support ◽  
Temperature Programmed ◽  
Diffuse Reflectance Infrared

AbstractThis work addresses the reduction of NOx by H2 under O2-rich conditions using Al2O3/SiO2-supported Pt catalysts with different loads of WOx promotor. The samples were thoroughly characterised by N2 physisorption, temperature-programmed desorption of CO, scanning electron microscopy, X-ray diffraction, laser raman spectroscopy, X-ray photoelectron spectroscopy and diffuse reflectance infrared fourier transform spectroscopy with probe molecule CO. The catalytic studies of the samples without WOx showed pronounced NOx conversion below 200 °C, whereas highest efficiency was related to small Pt particles. The introduction of WOx provided increasing deNOx activity as well as N2 selectivity. This promoting effect was referred to an additional reaction path at the Pt-WOx/Al2O3/SiO2 interface, whereas an electronic activation of Pt by strong metal support interaction was excluded. Graphic Abstract

BaO-Modified Pd-Based Catalyst for Methanol Oxidation

2012 ◽  
Vol 610-613 ◽  
pp. 577-580
Author(s):  
Xue Qiao Zhang ◽  
Ming Zhao ◽  
Zhi Xiang Ye ◽  
Sheng Yu Liu ◽  
Yao Qiang Chen
Keyword(s):  
Methanol Oxidation ◽  
Photoelectron Spectroscopy ◽  
Impregnation Method ◽  
Complete Conversion ◽  
X Ray ◽  
Support Interaction ◽  
Metal Support Interaction ◽  
Metal Support ◽  
Temperature Programmed ◽  
Conversion Temperature

Pd-based catalysts modified with BaO as a promoter was prepared by impregnation method. The catalyst was characterized by H2-temperature-programmed reduction (H2-TPR) and X-ray photoelectron spectroscopy (XPS). The catalytic activity towards methanol showed that the BaO modification promoted the conversion of methanol. The light-off temperature (T50), complete conversion temperature (T90) and ΔT (T90-T50) for methanol oxidation are 100°C, 125°C and 25°C, respectively. The H2-TPR results showed that the addition of BaO increased palladium highly dispersed and promoted the reductive ability. It also enhanced the metal-support interaction and increased the electronic surroundings of Pd and Ce sites, which maintained Pd in a higher oxidized state and Ce4+ in Ce3+ state, consequently increased the activity for methanol oxidation according to XPS measurements.

Evaluation of the Physiochemical Properties of Molybdenum Supported Catalysts

2012 ◽  
Vol 488-489 ◽  
pp. 206-210
Author(s):  
Muhammad Farooq ◽  
Anita Ramli ◽  
Duvvuri Subbarao
Keyword(s):  
Photoelectron Spectroscopy ◽  
Supported Catalysts ◽  
Analytical Techniques ◽  
Binding Energies ◽  
Impregnation Method ◽  
Physiochemical Properties ◽  
X Ray ◽  
Metal Support Interaction ◽  
Metal Support ◽  
Temperature Programmed

Molybdenum catalysts supported on γ-Al2O3and γ-Al2O3-MgO mixed oxide with varying loading of MgO (5, 10, 15, 20 wt% with respect to γ-Al2O3) were prepared successfully by wet impregnation method. The physiochemical properties of these synthesized Mo catalysts were studied by various analytical techniques such as N2adsorption–desorption (BET), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Temperature-programmed reduction (TPR).The results showed that the addition of MgO into the support affected the binding energies of the elements and reducibility of the metal oxides formed after calcination of catalyst samples due to change in metal-support interaction. Further, the characterization techniques showed that the active metal was well dispersed on the surface of support material.

scholarly journals Promoting Effect of Copper Loading and Mesoporosity on Cu-MOR in the Carbonylation of Dimethyl Ether to Methyl Acetate

Catalysts ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 696
Author(s):  
Raju Poreddy ◽  
Susanne Mossin ◽  
Anker Degn Jensen ◽  
Anders Riisager
Keyword(s):  
Dimethyl Ether ◽  
Photoelectron Spectroscopy ◽  
Gas Flow ◽  
Methyl Acetate ◽  
Coke Formation ◽  
Acid Property ◽  
Promoting Effect ◽  
Paramagnetic Resonance ◽  
X Ray ◽  
Temperature Programmed

Cu-mordenite (Cu-MOR) catalysts with different copper loadings were prepared, characterized and examined in continuous, gas-flow synthesis of methyl acetate (MA) by dimethyl ether (DME) carbonylation. Improved activity and selectivity were observed for Cu-MOR catalysts with up to 1 wt% Cu and X-ray photoelectron spectroscopy (XPS), electron paramagnetic resonance (EPR) spectroscopy and temperature-programmed reduction with hydrogen (H2-TPR) were used to elucidate the state of copper in the catalysts. Moreover, mesoporous MOR catalysts (RHMs) were prepared by mild stepwise recrystallization with X-ray powder diffraction (XRPD) and ammonia temperature-programmed desorption (NH3-TPD) demonstrating the retained MOR structure and the acid property of the catalysts, respectively. The RHM catalysts showed improved lifetime compared to pristine MOR giving a yield up to 78% MA with 93% selectivity after 5 h on stream (GHSV = 6711 h−1). Under identical reaction conditions, 1 wt% Cu-RHM catalysts had an even higher catalytic activity and durability resulting in a MA yield of 90% with 97% selectivity for 7–8 h of operation as well as a lower coke formation.

Redox Reactions of Iron and Uranium Dioxide in Simulated Cement Pore Water Under Anoxic Conditions

2002 ◽  
Vol 757 ◽  
Author(s):  
Daqing Cui ◽  
Kastriot Spahiu ◽  
Paul Wersin
Keyword(s):  
Photoelectron Spectroscopy ◽  
Redox Reactions ◽  
Pore Fluid ◽  
Laser Raman Spectroscopy ◽  
X Ray Diffraction ◽  
Exchange Reactions ◽  
Anoxic Conditions ◽  
X Ray ◽  
Laser Raman ◽  
Corrosion Of Iron

Results on the chemical behavior of Fe(0) and UO2(s), as well as the interaction between fresh and corroded iron with U(VI) in simulated cement contacting alkaline solution are reported. Batch experiments were conducted under anoxic conditions at different alkalinities and salt concentrations to investigate: (a) the corrosion of iron foils (b) the U(VI) removal by fresh, aged and pre-treated (with FeS or Fe3O4 layers) iron surfaces in a simulated cement pore fluid, (c) the dissolution rates of newly reduced UO2.00 slices in simulated cement pore fluid and KOH solutions (pH 12.7) and (d) the isotope exchange reactions between dissolved 235U(VI) and 238UO2(s). The reacted iron and UO2(s) surfaces were analyzed by X-ray diffraction (XRD), scanning electron microscopy-energy dispersive spectra (SEM-EDS), laser Raman spectroscopy and X-ray photoelectron, spectroscopy (XPS).

scholarly journals Propane and Naphthalene Oxidation over Gold-Promoted Cobalt Catalysts Supported on Zirconia

Catalysts ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 387
Author(s):  
María Silvia Leguizamón Aparicio ◽  
María Lucia Ruiz ◽  
Marco Antonio Ocsachoque ◽  
Marta Isabel Ponzi ◽  
Enrique Rodríguez-Castellón ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Photoelectron Spectroscopy ◽  
Cobalt Catalysts ◽  
Bet Surface Area ◽  
Promoting Effect ◽  
Propane Combustion ◽  
X Ray ◽  
Transmission Electron ◽  
Temperature Programmed ◽  
Supported Gold

Zirconia-supported gold-promoted cobalt catalysts were synthesized and tested for the complete oxidation of propane and naphthalene. The catalysts were characterized by BET surface area, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), powder X-ray diffraction (XRD), transmission electron microscopy (TEM), temperature-programmed reduction (TPR), and X-ray photoelectron spectroscopy (XPS). In both propane and naphthalene combustion reactions, the results obtained indicate that catalysts formulated with Co3O4 are more active than those containing only Au. Catalysts prepared using the deposit/precipitation (DP) method have better activity than those in which the traditional technique is used. Gold addition using the DP methods generates a promoting effect on the activity of cobalt-containing catalysts. The AuDpCoZt catalyst was found to be the most active for both propane and naphthalene combustion. The catalytic behavior of this sample is associated with a synergic effect between gold, cobalt, and the support, which is also evidenced by an increase in the reducibility of this catalytic system. The effect of the presence of NO in the feed was also analyzed for propane combustion.

scholarly journals Electrodeposited MnO2-based Capacitive Composite Electrodes for Pb2+ Adsorption

2020 ◽  
Vol 71 (7) ◽  
pp. 284-298
Author(s):  
Tang Chang-Bin ◽  
Niu Hao ◽  
Lu Yu-Xuan ◽  
Wang Fei ◽  
Zhang Yu-Jie ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Removal Rate ◽  
Nickel Foam ◽  
High Specific Capacitance ◽  
Laser Raman Spectroscopy ◽  
Order Kinetic ◽  
Composite Electrodes ◽  
X Ray ◽  
Laser Raman ◽  
Low Concentrations

In order to effectively realize the removal of low concentrations of lead ions in wastewater via capacitive deionization technology, MnO2 composite electrodes were prepared by a galvanostatic co-deposition approach, where polyaniline (PANI) and graphene were added to an MnO2 deposition solution and nickel foam was chosen as the substrate of the electrode. The microstructure, capacitance characteristics and adsorption behavior of Pb2+ ions of the electrodes were analyzed by scanning electron microscopy, X-ray diffraction, X ray photoelectron spectroscopy, laser Raman spectroscopy, cyclic voltammetry and capacitance deionization processes. The experimental results showed that the MnO2-PANI-graphene composite electrode has a high specific capacitance (132.8 F/g) and a 61.8% removal rate for simulated wastewater containing 20 mg/L Pb2 + ions under the conditions of 30�C and 1 mA/cm2, with the addition of 1 g/L PANI and 3 g/L graphene, respectively. Electroadsorption process was in accordance with the Lagergren quasi-second-order kinetic equation. The co-deposition of PANI and graphene oxide could play obvious role in enhancing the adsorption capacity and stability of the electrodes.

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