Surface structure and catalytic activity of molybdenum(VI) oxide/aluminum oxide catalysts in the hydrodesulfurization of thiophene studied by x-ray photoelectron spectroscopy

1980 ◽  
Vol 84 (14) ◽  
pp. 1833-1840 ◽  
Author(s):  
Yasuaki Okamoto ◽  
Hiroyuki Tomioka ◽  
Yukihiro Katoh ◽  
Toshinobu Imanaka ◽  
Shiichiro Teranishi
Keyword(s):  
Catalytic Activity ◽  
Aluminum Oxide ◽  
Surface Structure ◽  
Photoelectron Spectroscopy ◽  
Oxide Catalysts ◽  
X Ray

Property of Cu2O-CuO/ZSM-5 nanocomposite and degradation process of azo dye AO7 without sacrificial agent (H2O2)

2016 ◽  
Vol 73 (11) ◽  
pp. 2747-2753 ◽  
Author(s):  
Wusong Kong ◽  
Hongxia Qu ◽  
Peng Chen ◽  
Weihua Ma ◽  
Huifang Xie
Keyword(s):  
Catalytic Activity ◽  
Aqueous Solutions ◽  
Photoelectron Spectroscopy ◽  
Oxygen Demand ◽  
Operating Conditions ◽  
Surface Element ◽  
Impregnation Method ◽  
X Ray ◽  
Initial Ph ◽  
Sacrificial Agent

In this study, Cu2O-CuO/ZSM-5 nanocomposite was synthesized by the impregnation method, and its catalytic performance for the destruction of AO7 in aqueous solutions was investigated. The morphology, structure and surface element valence state of Cu2O-CuO/ZSM-5 were characterized by transmission electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. The operating conditions on the degradation of AO7 by Cu2O-CuO/ZSM-5, such as initial pH values, concentration of AO7 and catalyst dosage were investigated and optimized. The results showed that the sample had good catalytic activity for destruction of AO7 in the absence of a sacrificial agent (e.g. H2O2): it could degrade 91% AO7 in 140 min at 25 °C and was not restricted by the initial pH of the AO7 aqueous solutions. Cu2O-CuO/ZSM-5 exhibited stable catalytic activity with little loss after three successive runs. The total organic carbon and chemical oxygen demand removal efficiencies increased rapidly to 69.36% and 67.3% after 120 min of treatment by Cu2O-CuO/ZSM-5, respectively.

X-Ray Photoelectron Spectroscopy Study on the Interaction of Yttrium-Aluminum Oxide with Fluorine-Based Plasma

2011 ◽  
Vol 94 (10) ◽  
pp. 3455-3459 ◽  
Author(s):  
Dae-Min Kim ◽  
Sang-Ho Lee ◽  
William B. Alexander ◽  
Kyeong-Beom Kim ◽  
Yoon-Suk Oh ◽  
...  
Keyword(s):  
Aluminum Oxide ◽  
Photoelectron Spectroscopy ◽  
Spectroscopy Study ◽  
Yttrium Aluminum Oxide ◽  
X Ray ◽  
Yttrium Aluminum

scholarly journals Combustion Synthesis of Non-Precious CuO-CeO2 Nanocrystalline Catalysts with Enhanced Catalytic Activity for Methane Oxidation

Materials ◽  
2019 ◽  
Vol 12 (6) ◽  
pp. 878 ◽  
Author(s):  
Abdallah Zedan ◽  
Amina AlJaber
Keyword(s):  
Solid Solution ◽  
Raman Spectroscopy ◽  
Catalytic Activity ◽  
Electronic Properties ◽  
Combustion Synthesis ◽  
Mixed Oxide ◽  
Oxide Catalysts ◽  
Ch4 Oxidation ◽  
X Ray ◽  
Mixed Oxide Catalysts

In this study, xCuO-CeO2 mixed oxide catalysts (Cu weight ratio x = 1.5, 3, 4.5, 6 and 15 wt.%) were prepared using solution combustion synthesis (SCS) and their catalytic activities towards the methane (CH4) oxidation reaction were studied. The combustion synthesis of the pure CeO2 and the CuO-CeO2 solid solution catalysts was performed using copper and/or cerium nitrate salt as an oxidizer and citric acid as a fuel. A variety of standard techniques, including scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), thermo-gravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy were employed to reveal the microstructural, crystal, thermal and electronic properties that may affect the performance of CH4 oxidation. The CuO subphase was detected in the prepared solid solution and confirmed with XRD and Raman spectroscopy, as indicated by the XRD peaks at diffraction angles of 35.3° and 38.5° and the Ag Raman mode at 289 cm−1, which are characteristics of tenorite CuO. A profound influence of Cu content was evident, not only affecting the structural and electronic properties of the catalysts, but also the performance of catalysts in the CH4 oxidation. The presence of Cu in the CeO2 lattice obviously promoted its catalytic activity for CH4 catalytic oxidation. Among the prepared catalysts, the 6% CuO-CeO2 catalyst demonstrated the highest performance, with T50 = 502 °C and T80 = 556 °C, an activity that is associated with the availability of a fine porous structure and the enhanced surface area of this catalyst. The results demonstrate that nanocrystalline copper-ceria mixed oxide catalysts could serve as an inexpensive and active material for CH4 combustion.

scholarly journals Amino-Modified Silica as Effective Support of the Palladium Catalyst for 4-Nitroaniline Hydrogenation

Catalysts ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 375
Author(s):  
Adele R. Latypova ◽  
Maxim D. Lebedev ◽  
Evgeniy V. Rumyantsev ◽  
Dmitry V. Filippov ◽  
Olga V. Lefedova ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Catalytic Activity ◽  
Electron Donor ◽  
Photoelectron Spectroscopy ◽  
Functionalized Silica ◽  
Amino Groups ◽  
Modified Silica ◽  
Pulse Technique ◽  
X Ray ◽  
Transmission Electron

The article describes the synthesis of aminoorgano-functionalized silica as a prospective material for catalysis application. The amino groups have electron donor properties which are valuable for the metal chemical state of palladium. Therefore, the presence of electron donor groups is important for increasing catalysts’ stability. The research is devoted to the investigation of silica amino-modified support influence on the activity and stability of palladium species in 4-nitroaniline hydrogenation process. A series of catalysts with different supports such as SiO2, SiO2-C3H6-NH2 (amino-functionalized silica), γ-Al2O3 and activated carbon were studied. The catalytic activity was studied in the hydrogenation of 4-nitroaniline to 1,4-phenylenediamine. The catalysts were characterized by scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy and chemisorption of hydrogen by the pulse technique. The 5 wt.% Pd/SiO2-C3H6-NH2 catalyst exhibited the highest catalytic activity for 4-nitroaniline hydrogenation with 100% conversion and 99% selectivity with respect to 1,4-phenylenediamine.

A Study of Copper-Chromium Oxide Catalysts and a Method to Determine Catalytic Activities

1963 ◽  
Vol 7 ◽  
pp. 229-239
Author(s):  
M. Stammler ◽  
M. Pyzyna
Keyword(s):  
Catalytic Activity ◽  
Chromium Oxide ◽  
Oxide Catalysts ◽  
Linear Absorption ◽  
X Ray ◽  
Chromium Spinel ◽  
Copper Chromium ◽  
The Difference ◽  
Two Phases ◽  
Chromium Oxide Catalysts

AbstractAn extensive investigation of chemical composition, particle size, and surface area of copper-chromium oxide catalysts has been made. The two phases present in the activated material are copper oxide (CuO) and copper-chromium spinel (CuCr2O4). The crystallite size of the CuO phase (determined by X-ray diffraction line broadening) can be correlated with the catalytic activity measured on a CO-CO2 oxidation reaction. The catalytic activity of the oxide catalyst can be expressed as a function of the X-ray fluorescence intensity of the Cu Kα line even on changing the absolute copper concentration up to 3%. An attempt is made to explain this phenomenon by the heterogeneity effect caused by the difference in the linear absorption factors for the Cu Kα radiation in the system CuO-CuCr2O4.

scholarly journals Aerobic Oxidation of 5-Hydroxymethylfurfural over Ag Nanoparticle Catalysts Stabilized by Polyvinylpyrrolidone with Different Molecular Weights

Nanomaterials ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1624
Author(s):  
Haian Xia ◽  
Jiahuan An ◽  
Weizi Zhang
Keyword(s):  
Catalytic Activity ◽  
Photoelectron Spectroscopy ◽  
Catalytic Properties ◽  
Aerobic Oxidation ◽  
Ag Nps ◽  
Oxidation Activity ◽  
X Ray ◽  
Remarkable Effect ◽  
Molecular Weights ◽  
Metal Support Interaction

The metal–support interaction (MSI) has a remarkable effect on the catalytic properties, but how to precisely modulate its degree remains a huge challenge. Herein, polyvinylpyrrolidone (PVP) with three different molecular weights (MWs) (24, 58, and 130 kDa) was used as a capping agent to fabricate Ag nanoparticles (NPs) supported on ZrO2. The physiochemical properties of the catalysts were characterized by X-ray diffraction (XRD), Transmission Electron Microscope (TEM), X-ray Photoelectron Spectroscopy (XPS), and Fourier transform infrared (FT-IR) techniques. The impacts of MSI on the catalytic activity and reaction kinetics for aerobic oxidation of 5-hydroxymethylfurfural (HMF) were investigated. The results showed that the introduction of PVP with various MWs could efficiently tailor the interfacial interactions and charge transfers (CT) among PVP, the support, and Ag NPs, thereby affecting the oxidation activity of HMF. The turnover number (TON) for HMF oxidation decreases in the order of unsupported colloidal Ag clusters > Ag/ZrO2 (58,000) > Ag/ZrO2 (130,000) > Ag/ZrO2 (24,000) > Ag/ZrO2. The reason for this large difference in the catalytic activity for HMF oxidation is that various MWs of PVP result in a change of MSI, thereby facilitating CT from PVP to Ag metal sites. This study offers a new strategy for modulating MSI by varying the MW of capping agents, thereby tuning the catalytic properties in the oxidation of HMF.

scholarly journals Evolution of the pore and framework structure of NaY zeolite during alkali treatment and its effect on methanol oxidative carbonylation over a CuY catalyst

2020 ◽  
Vol 44 (11-12) ◽  
pp. 710-720
Author(s):  
Lifei Yan ◽  
Tingjun Fu ◽  
Jiajun Wang ◽  
Nilesh Narkhede ◽  
Zhong Li
Keyword(s):  
Catalytic Activity ◽  
Surface Area ◽  
Photoelectron Spectroscopy ◽  
Dimethyl Carbonate ◽  
Alkali Treatment ◽  
Oxidative Carbonylation ◽  
Framework Structure ◽  
Y Zeolite ◽  
Cage Structure ◽  
X Ray

Alkali treatment is widely used on aluminosilicate zeolites with high Si/Al ratios in order to fabricate mesopores in the framework. However, for zeolites with low Si/Al ratios, the effect of alkali treatment on the pore and framework structure needed further study. In this work, Y zeolite is treated with NaOH solutions of different concentrations and is used as the support for Cu-based catalysts for oxidative carbonylation of methanol to dimethyl carbonate. The physicochemical properties of the supports and corresponding catalysts are characterized by N2 adsorption–desorption, X-ray diffraction, X-ray fluorescence, transmission electron microscopy, inductively coupled plasma mass spectrometry, X-ray photoelectron spectroscopy, and H2-temperature-programmed reduction analyses. The results show that no obvious mesopores are formed under alkali treatment, even at high NaOH concentration. However, amorphous species present in the micropores of Y zeolite are removed, which increases the micropore surface area as well as the crystallinity. Simultaneously, the cage structure is partially destroyed, which also leads to a slight increase of the pore volume and surface area. The altered micropore structure eventually increases the content and accessibility of the exchanged Cu species, which is beneficial to the catalytic activity. When the concentration of NaOH is 0.6 M, the space time yield of dimethyl carbonate for the corresponding catalyst was 151.4 mg g−1 h−1 which is 3.3-fold higher than that of the untreated-Y-zeolite-supported Cu catalyst. However, further increasing the alkali treatment strength can seriously destroy the basic aluminosilicate structure of the Y zeolite and decrease its intrinsic ion-exchange capacity. This results in the formation of agglomerated CuO on the catalyst surface, which was not conducive to catalytic activity.

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