scholarly journals The Selective Oxidation of Cyclohexane via In-situ H2O2 Production Over Supported Pd-based Catalysts

2021 ◽  
Author(s):  
Caitlin M. Crombie ◽  
Richard J. Lewis ◽  
Dávid Kovačič ◽  
David J. Morgan ◽  
Thomas J. A. Slater ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Catalytic Performance ◽  
Environmental Concerns ◽  
H2o2 Production ◽  
X Ray ◽  
Mixed Oxidation ◽  
Order Of Magnitude ◽  
Oil Concentration ◽  
Supported Pd

AbstractThe oxidation of cyclohexane via the in-situ production of H2O2 from molecular H2 and O2 offers an attractive route to the current industrial means of producing cyclohexanone and cyclohexanol (KA oil), key materials in the production of Nylon. The in-situ route has the potential to overcome the significant economic and environmental concerns associated with the use of commercial H2O2, while also allowing for the use of far lower reaction temperatures than those typical of the purely aerobic route to KA oil. Herein we demonstrate the efficacy of a series of bi-functional Pd-based catalysts, which offer appreciable concentrations of KA oil, under conditions where limited activity is observed using O2 alone. In particular the introduction of V into a supported Pd catalyst is seen to improve KA oil concentration by an order of magnitude, compared to the Pd-only analogue. In particular we ascribe this improvement in catalytic performance to the development of Pd domains of mixed oxidation state upon V incorporation as evidenced through X-ray photoelectron spectroscopy. Graphic Abstract

scholarly journals Effect of Ce-modified Fe/ZSM-5 zeolite for selective catalytic reduction of NOx by ammonia

2020 ◽  
Vol 218 ◽  
pp. 03032
Author(s):  
Chenxi Li ◽  
Fanwei Meng ◽  
Qing Ye
Keyword(s):  
Selective Catalytic Reduction ◽  
Photoelectron Spectroscopy ◽  
Catalytic Reduction ◽  
Catalytic Performance ◽  
Acid Sites ◽  
Impregnation Method ◽  
Adsorption Ability ◽  
In Situ Drifts ◽  
X Ray

A series of xCe-Fe/ZSM-5 (x = 0, 0.25, 0.5 wt%) samples were prepared by the impregnation method, and the catalytic activity was evaluated by the selective catalytic reduction of NOx with ammonia (NH3-SCR). The physicochemical properties of prepared samples were characterized by various techniques such as X-ray diffraction (XRD), Brunner-Emmet-Teller (BET) measurement, hydrogen temperatureprogrammed reduction (H2-TPR), X-ray photoelectron spectroscopy (XPS), ammonia temperatureprogrammed desorption (NH3-TPD) and in situ diffuse reflectance infrared Fourier transform spectroscopy (in situ DRIFTS). XRD and BET results demonstrated that Ce and Fe species were uniform dispersed on the surface of the ZSM-5 zeolite and the micropore structure of ZSM-5 was still maintained. H2-TPR analysis indicated that the doping of Ce created more isolated Ce4+ and Fe3+ on the surface of catalysts, and the abundant Ce4+ and Fe3+ could enhance the reduction ability of catalysts. XPS analysis suggested that the doping of Ce could generate more oxygen vacancies, thereby increasing the number of chemisorption oxygen. According to the in-situ DRIFTS and NH3-TPD results, Ce species provided more acidic sites, which is beneficial to the NH3 adsorption ability of ZSM-5 zeolite. Additionally, the abundant chemisorption oxygen, medium and strong Brønsted acid sites, excellent NH3 adsorption ability and outstanding reduction property are beneficial to the NH3-SCR reaction. Among all prepared samples, the 0.25Ce-Fe/ZSM-5 sample possessed the widest reaction temperature window and the best catalytic performance (NO conversion over 98% at 350-450 °C), which was associated with the abundant acid sites and remarkable adsorption ability of NH3, outstanding redox ability and abundant chemisorption oxygen after the doping of Ce.

Study on Effect Recyclability of Ru/Bentonite-TiO2 Catalysts in Glycerol Hydrogenolysis Reaction Using X-Ray Photoelectron Spectroscopy (XPS)

2012 ◽  
Vol 620 ◽  
pp. 289-294 ◽  
Author(s):  
Noraini Hamzah ◽  
Nor Asikin Mohamad Nordin ◽  
Wan Nor Roslam Wan Isahak ◽  
Mohamad Bin Kassim ◽  
Mohd Ambar Yarmo
Keyword(s):  
Active Site ◽  
Photoelectron Spectroscopy ◽  
Hydrogen Pressure ◽  
Catalytic Performance ◽  
Atomic Ratio ◽  
Xps Analysis ◽  
X Ray ◽  
Glycerol Hydrogenolysis ◽  
Repeated Runs

Recyclability effect on catalytic performance of Ru supported on the mixture of bentonite-TiO2 for the hydrogenolysis of glycerol was investigated under reaction condition of 150°C, 2.0 MPa hydrogen pressure and 7 h reaction time. Interestingly, the recovered Ru/bentonite-TiO2 catalyst was found to be active in the repeated runs. The conversion of glycerol increased in the four successive reactions as follows: 61.3%, 65.6%, 68.1% and 75.3%. This suggested that a sort of metal activation affect such as in situ reduction occurred during the repeated reaction. In order to confirm in situ reduction had occurred during the repeated reaction, XPS analysis of used catalyst after each reaction were carried out to study the chemical state of Ru 3d species. Narrow scan of peak Ru 3d revealed that intensity of Ru 3d5/2 peak at BE 280.0 eV which is corresponding to Ru0 species increased until three cycle reaction. This result confirmed that in situ reduction had occurred during the repeated reaction and this made the activities of the catalyst increased upon recycling due to the availability of more metallic Ru on the surface of the catalyst. This study also shows that conversion of glycerol increased linearly with the percentage atomic ratio of Ru metal active site available on the surface of catalyst.

scholarly journals In situ monitoring of the influence of water on DNA radiation damage by near-ambient pressure X-ray photoelectron spectroscopy

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Marc Benjamin Hahn ◽  
Paul M. Dietrich ◽  
Jörg Radnik
Keyword(s):  
Dna Damage ◽  
Radiation Damage ◽  
Photoelectron Spectroscopy ◽  
Ambient Pressure ◽  
In Situ Monitoring ◽  
Strong Increase ◽  
Oh Radicals ◽  
Strand Breaks ◽  
X Ray

AbstractIonizing radiation damage to DNA plays a fundamental role in cancer therapy. X-ray photoelectron-spectroscopy (XPS) allows simultaneous irradiation and damage monitoring. Although water radiolysis is essential for radiation damage, all previous XPS studies were performed in vacuum. Here we present near-ambient-pressure XPS experiments to directly measure DNA damage under water atmosphere. They permit in-situ monitoring of the effects of radicals on fully hydrated double-stranded DNA. The results allow us to distinguish direct damage, by photons and secondary low-energy electrons (LEE), from damage by hydroxyl radicals or hydration induced modifications of damage pathways. The exposure of dry DNA to x-rays leads to strand-breaks at the sugar-phosphate backbone, while deoxyribose and nucleobases are less affected. In contrast, a strong increase of DNA damage is observed in water, where OH-radicals are produced. In consequence, base damage and base release become predominant, even though the number of strand-breaks increases further.

scholarly journals Enhanced Selective Oxidation of Benzyl Alcohol via In Situ H2O2 Production over Supported Pd-Based Catalysts

ACS Catalysis ◽  
2021 ◽  
pp. 2701-2714
Author(s):  
Caitlin M. Crombie ◽  
Richard J. Lewis ◽  
Rebekah L. Taylor ◽  
David J. Morgan ◽  
Thomas E. Davies ◽  
...  
Keyword(s):  
Benzyl Alcohol ◽  
Selective Oxidation ◽  
H2o2 Production ◽  
Oxidation Of Benzyl Alcohol ◽  
Supported Pd

In situ Hard X-ray Photoelectron Spectroscopy on the Origin of Irreversibility in Electrochromic LixWO3 Thin Films

2021 ◽  
pp. 150898
Author(s):  
Makoto Takayanagi ◽  
Takashi Tsuchiya ◽  
Shigenori Ueda ◽  
Tohru Higuchi ◽  
Kazuya Terabe
Keyword(s):  
Thin Films ◽  
Photoelectron Spectroscopy ◽  
X Ray

Incorporation and Role of Nitrogen During Oxynitridation of Silicon Studied by Photoelectron Spectroscopy

1999 ◽  
Vol 567 ◽  
Author(s):  
Masayuki Suzuki ◽  
Yoji Saito
Keyword(s):  
Photoelectron Spectroscopy ◽  
High Vacuum ◽  
Oxide Films ◽  
Silicon Surfaces ◽  
Gaseous Mixtures ◽  
X Ray ◽  
Initial Stage ◽  
Thermal Stability Of

ABSTRACTWe tried direct oxynitridation of silicon surfaces by remote-plasma-exited nitrogen and oxygen gaseous mixtures at 700°C in a high vacuum. The oxynitrided surfaces were investigated with in-situ X-ray photoelectron spectroscopy. With increase of the oxynitridation time, the surface density of nitrogen gradually increases, but that of oxygen shows nearly saturation behavior after the rapid increase in the initial stage. We also annealed the grown oxynitride and oxide films to investigate the role of the contained nitrogen. The desorption rate of oxygen from the oxynitride films is much less than that from oxide films. We confirmed that nitrogen stabilizes the thermal stability of these oxynitride films.

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