scholarly journals Regulation of Cu Species in CuO/SiO2 and Its Structural Evolution in Ethynylation Reaction

Nanomaterials ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 842 ◽  
Author(s):  
Haitao Li ◽  
Lijun Ban ◽  
Zhipeng Wang ◽  
Pingfan Meng ◽  
Yin Zhang ◽  
...  
Keyword(s):  
Structural Evolution ◽  
High Dispersion ◽  
Impregnation Method ◽  
Initial Activity ◽  
Optimal Service ◽  
Nano Catalyst ◽  
Large Particles ◽  
Low Exposure ◽  
The Stability

A Cu-based nano-catalyst has been widely used in the ethynylation of formaldehyde; however, the effects of the presence of Cu on the reaction have not yet been reported. CuO/SiO2 catalysts with different Cu species were prepared by impregnation (IM), deposition–precipitation (DP), and ammonia evaporation (AE). The structural evolution of the Cu species in different states of the ethynylation reaction and the structure–activity relationship between the existence state of the Cu species and the catalytic properties of the ethynylation reaction were studied. The results show that the Cu species in the CuO/SiO2 (IM), prepared using the impregnation method, are in the form of bulk CuO, with large particles and no interactions with the support. The bulk CuO species are transformed into Cu+ with a low exposure surface at the beginning of the reaction, which is easily lost. Thus, this approach shows the lowest initial activity and poor cycle stability. A high dispersion of CuO and copper phyllosilicate exists in CuO/SiO2 (DP). The former makes the catalyst have the best initial activity, while the latter slows release, maintaining the stability of the catalyst. There is mainly copper phyllosilicate in CuO/SiO2 (AE), which is slowly transformed into a highly dispersed and stable Cu+ center in the in situ reaction. Although the initial activity of the catalyst is not optimal, it has the optimal service stability.

scholarly journals Synergistic Effects of Co3O4-CeO2 Nanoparticles towards Catalytic Oxidation of Aromatic Hydrocarbons: A Study in Association with Carbon Monoxide and Humidity

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Trung Dang-Bao ◽  
Hong Phuong Phan ◽  
Phung Anh Nguyen ◽  
Pham Phuong Trang Vo ◽  
Van Tien Huynh ◽  
...  
Keyword(s):  
Carbon Monoxide ◽  
Catalytic Activity ◽  
Catalytic Oxidation ◽  
Synergistic Effects ◽  
Active Oxygen Species ◽  
High Dispersion ◽  
High Catalytic Activity ◽  
Impregnation Method ◽  
Temperature Programmed ◽  
The Stability

In this study, a series of Co3O4-CeO2 nanocomposites with various Co3O4 loading were fabricated by the impregnation method using cobalt(II) acetate as the cobalt precursor for the treatment of benzene, toluene, ethylbenzene, and xylene (BTEX). The as-prepared Co3O4-CeO2 nanocomposites were thoroughly characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Brumauer-Emmett-Teller (BET), hydrogen temperature-programmed reduction (H2-TPR), and temperature-programmed desorption (O2-TPD). The excellent reproduction of active oxygen species caused by the high dispersion of Co3O4 crystals on the CeO2 supports was established. In addition, the reduction peaks of Co3O4-CeO2 nanocomposites were found at much lower temperatures compared to pure CeO2, considering their unique redox property influencing on the high catalytic activity. Among the characterized materials, the 5.0 wt.% Co3O4 supported on CeO2 (5.0Co–Ce) was the best system for catalytic oxidation of xylene, along with excellent performances in the cases of benzene, ethylbenzene, and toluene. Its catalytic activity increased in the order: benzene < xylene < ethylbenzene < toluene . Furthermore, the addition of carbon monoxide (CO) as a coreactant permitted to improve the catalytic performances in such oxidations as well as the stability of as-prepared catalysts, even under humid conditions.

Synthesized BG-MCM-41 as Support Catalyst for Fenton-Like Reaction of Lignin Degradation

2014 ◽  
Vol 931-932 ◽  
pp. 12-16
Author(s):  
Pongsert Sriprom ◽  
Arthit Neramittagapong ◽  
Sutasinee Neramittagapong
Keyword(s):  
Aqueous Solution ◽  
Surface Area ◽  
Lignin Degradation ◽  
Batch Reactor ◽  
Bet Surface Area ◽  
Impregnation Method ◽  
Hydrothermal Technique ◽  
The Stability ◽  
Mcm 41

Lignin was degraded by Fenton-like reaction using Cu-BG-MCM41, in which BG-MCM41 was synthesized by hydrothermal technique from Bagasse ash (BG) as a support. Cu was immobilized on BG-MCM41 by in situ hydrothermal and impregnation method and characterized by XRD and BET surface area. The Fenton-like reactions were carried out in a batch reactor using 5wt%CuO/SiO2, 10wt%CuO/SiO2, 5wt%Cu-BG-MCM41 and 10wt%Cu-BG-MCM41 at the pH of 3 and the temperature of 80°C. The Cu loading, pH, and temperature affected lignin degradation. The efficiency of lignin degradation obtained were 95% for 5wt%CuO/SiO2, 95% for 10wt%CuO/SiO2, 65% for 5wt%Cu-BG-MCM41 and 96% for 10wt%Cu-BG-MCM41 at the pH of 3 and 80°C for 30 min. The results show that pH and temperature affected the stability of Cu loading, in which it was leached into the aqueous solution and that the reaction will occur in the aqueous solution more than on the surface of catalyst. Thus, 5wt%Cu-BG-MCM41 has the highest stability for Fenton-like reactions.

scholarly journals Highly Active CuO/KCC−1 Catalysts for Low-Temperature CO Oxidation

Processes ◽  
2022 ◽  
Vol 10 (1) ◽  
pp. 145
Author(s):  
Yiwei Luo ◽  
Yonglong Li ◽  
Conghui Wang ◽  
Jing Wang ◽  
Wenming Liu ◽  
...  
Keyword(s):  
Co Oxidation ◽  
Active Oxygen Species ◽  
Copper Catalysts ◽  
High Dispersion ◽  
Impregnation Method ◽  
Active Components ◽  
Highly Active ◽  
Low Temperature Co Oxidation ◽  
Oxidation Performance ◽  
The Stability

Copper catalysts have been extensively studied for CO oxidation at low temperatures. Previous findings on the stability of such catalysts, on the other hand, revealed that they deactivated badly under extreme circumstances. Therefore, in this work, a series of KCC−1-supported copper oxide catalysts were successfully prepared by impregnation method, of which 5% CuO/KCC−1 exhibited the best activity: CO could be completely converted at 120 °C. The 5% CuO/KCC−1 catalyst exhibited better thermal stability, which is mainly attributed to the large specific surface area of KCC−1 that facilitates the high dispersion of CuO species, and because the dendritic layered walls can lengthen the movement distances from particle-to-particle, thus helping to slow down the tendency of active components to sinter. In addition, the 5% CuO/KCC−1 has abundant mesoporous and surface active oxygen species, which are beneficial to the mass transfer and promote the adsorption of CO and the decomposition of Cu+–CO species, thus improving the CO oxidation performance of the catalyst.

Influence of ion-milling on the T2 phase in Al-2.5%Li-2.5%Cu alloy

1989 ◽  
Vol 47 ◽  
pp. 288-289
Author(s):  
J. R. Reed ◽  
D. J. Michel ◽  
P. R. Howell
Keyword(s):  
Thin Foil ◽  
Icosahedral Symmetry ◽  
Ion Milling ◽  
Cu Alloy ◽  
Thin Foils ◽  
Heat Treated ◽  
Aluminum Solid Solution ◽  
In Situ Heating ◽  
The Stability

The Al6Li3Cu (T2) phase, which exhibits five-fold or icosahedral symmetry, forms through solid state precipitation in dilute Al-Li-Cu alloys. Recent studies have reported that the T2 phase transforms either during TEM examination of thin foils or following ion-milling of thin foil specimens. Related studies have shown that T2 phase transforms to a microcrystalline array of the TB phase and a dilute aluminum solid solution during in-situ heating in the TEM. The purpose of this paper is to report results from an investigation of the influence of ion-milling on the stability of the T2 phase in dilute Al-Li-Cu alloy.The 3-mm diameter TEM disc specimens were prepared from a specially melted Al-2.5%Li-2.5%Cu alloy produced by conventional procedures. The TEM specimens were solution heat treated 1 h at 550°C and aged 1000 h at 190°C in air to develop the microstructure. The disc specimens were electropolished to achieve electron transparency using a 20:80 (vol. percent) nitric acid: methanol solution at -60°C.

STRUCTURAL EVOLUTION OF EXCEPTIONALLY IRON-DEFICIENT HEMATITE NANOCRYSTALS AS OBSERVED BY IN SITU SYNCHROTRON X-RAY DIFFRACTION

2019 ◽  
Author(s):  
Si Athena Chen ◽  
◽  
Peter Heaney ◽  
Jeffrey E. Post ◽  
Peter J. Eng ◽  
...  
Keyword(s):  
Structural Evolution ◽  
X Ray Diffraction ◽  
X Ray ◽  
Iron Deficient

scholarly journals Insight into the Promoting Role of Er Modification on SO2 Resistance for NH3-SCR at Low Temperature over FeMn/TiO2 Catalysts

Catalysts ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 618
Author(s):  
Huan Du ◽  
Zhitao Han ◽  
Xitian Wu ◽  
Chenglong Li ◽  
Yu Gao ◽  
...  
Keyword(s):  
Low Temperature ◽  
Catalyst Surface ◽  
Impregnation Method ◽  
In Situ Drifts ◽  
Tio2 Catalyst ◽  
Nh3 Scr ◽  
Nh3 Adsorption ◽  
So2 Resistance ◽  
Fast Scr

Er-modified FeMn/TiO2 catalysts were prepared through the wet impregnation method, and their NH3-SCR activities were tested. The results showed that Er modification could obviously promote SO2 resistance of FeMn/TiO2 catalysts at a low temperature. The promoting effect and mechanism were explored in detail using various techniques, such as BET, XRD, H2-TPR, XPS, TG, and in-situ DRIFTS. The characterization results indicated that Er modification on FeMn/TiO2 catalysts could increase the Mn4+ concentration and surface chemisorbed labile oxygen ratio, which was favorable for NO oxidation to NO2, further accelerating low-temperature SCR activity through the “fast SCR” reaction. As fast SCR reaction could accelerate the consumption of adsorbed NH3 species, it would benefit to restrain the competitive adsorption of SO2 and limit the reaction between adsorbed SO2 and NH3 species. XPS results indicated that ammonium sulfates and Mn sulfates formed were found on Er-modified FeMn/TiO2 catalyst surface seemed much less than those on FeMn/TiO2 catalyst surface, suggested that Er modification was helpful for reducing the generation or deposition of sulfate salts on the catalyst surface. According to in-situ DRIFTS the results of, the presence of SO2 in feeding gas imposed a stronger impact on the NO adsorption than NH3 adsorption on Lewis acid sites of Er-modified FeMn/TiO2 catalysts, gradually making NH3-SCR reaction to proceed in E–R mechanism rather than L–H mechanism. DRIFTS.

scholarly journals Underground Microseismic Event Monitoring and Localization within Sensor Networks

Sensors ◽  
2021 ◽  
Vol 21 (8) ◽  
pp. 2830
Author(s):  
Sili Wang ◽  
Mark P. Panning ◽  
Steven D. Vance ◽  
Wenzhan Song
Keyword(s):  
Sensor Networks ◽  
Real Time ◽  
Information Needs ◽  
Localization Algorithm ◽  
Distributed Sensors ◽  
Distributed Sensor ◽  
Microseismic Events ◽  
The Stability ◽  
Stability And Accuracy

Locating underground microseismic events is important for monitoring subsurface activity and understanding the planetary subsurface evolution. Due to bandwidth limitations, especially in applications involving planetarily-distributed sensor networks, networks should be designed to perform the localization algorithm in-situ, so that only the source location information needs to be sent out, not the raw data. In this paper, we propose a decentralized Gaussian beam time-reverse imaging (GB-TRI) algorithm that can be incorporated to the distributed sensors to detect and locate underground microseismic events with reduced usage of computational resources and communication bandwidth of the network. After the in-situ distributed computation, the final real-time location result is generated and delivered. We used a real-time simulation platform to test the performance of the system. We also evaluated the stability and accuracy of our proposed GB-TRI localization algorithm using extensive experiments and tests.

scholarly journals A Superhydrophobic, Antibacterial, and Durable Surface of Poplar Wood

Nanomaterials ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1885
Author(s):  
Xinyu Wu ◽  
Feng Yang ◽  
Jian Gan ◽  
Zhangqian Kong ◽  
Yan Wu
Keyword(s):  
Stearic Acid ◽  
Antibacterial Properties ◽  
Alkali Resistance ◽  
Poplar Wood ◽  
X Ray Diffraction ◽  
X Ray ◽  
Different Temperatures ◽  
Acid And Alkali Resistance ◽  
The Stability

The silver particles were grown in situ on the surface of wood by the silver mirror method and modified with stearic acid to acquire a surface with superhydrophobic and antibacterial properties. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and X-ray energy spectroscopy (XPS) were used to analyze the reaction mechanism of the modification process. Scanning electron microscopy (SEM) and contact angle tests were used to characterize the wettability and surface morphology. A coating with a micro rough structure was successfully constructed by the modification of stearic acid, which imparted superhydrophobicity and antibacterial activity to poplar wood. The stability tests were performed to discuss the stability of its hydrophobic performance. The results showed that it has good mechanical properties, acid and alkali resistance, and UV stability. The durability tests demonstrated that the coating has the function of water resistance and fouling resistance and can maintain the stability of its hydrophobic properties under different temperatures of heat treatment.

In situ synchrotron small- and wide-angle X-ray study on the structural evolution of Kevlar fiber under uniaxial stretching

RSC Advances ◽  
2016 ◽  
Vol 6 (85) ◽  
pp. 81552-81558 ◽  
Author(s):  
Xiaoyun Li ◽  
Feng Tian ◽  
Ping Zhou ◽  
Chunming Yang ◽  
Xiuhong Li ◽  
...  
Keyword(s):  
Structural Evolution ◽  
Wide Angle ◽  
Uniaxial Stretching ◽  
X Ray ◽  
Kevlar Fiber

In situ SAXS and WAXS study on the structural evolution and mechanism of two different Kevlar fibers during stretching.

Structural evolution of NASICON-type Li1+xAlxGe2−x(PO4)3 using in situ synchrotron X-ray powder diffraction

2016 ◽  
Vol 4 (20) ◽  
pp. 7718-7726 ◽  
Author(s):  
Dorsasadat Safanama ◽  
Neeraj Sharma ◽  
Rayavarapu Prasada Rao ◽  
Helen E. A. Brand ◽  
Stefan Adams
Keyword(s):  
Solid Electrolyte ◽  
Diffraction Study ◽  
Powder Diffraction ◽  
Structural Evolution ◽  
X Ray Diffraction ◽  
X Ray ◽  
Nasicon Type ◽  
Precursor Glass

In situ synchrotron X-ray diffraction study of the synthesis of solid-electrolyte Li1+xAlxGe2−x(PO4)3 (LAGP) from the precursor glass reveals that an initially crystallized dopant poor phase transforms into the Al-doped LAGP at 800 °C.

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