Effective Decomposition of Nitric Oxide Using Pd/YSZ/Au Electrochemical Membrane Reactor

1996 ◽  
Vol 454 ◽  
Author(s):  
Y. Kanai ◽  
H. Ichimura ◽  
H. Kawakami
Keyword(s):  
Catalytic Activity ◽  
Membrane Reactor ◽  
Electrical Potential ◽  
No Decomposition ◽  
Oxygen Species ◽  
Surface Oxygen ◽  
Rate Determining Step ◽  
Electrochemical Membrane Reactor ◽  
Three Phase ◽  
Lower Temperature

ABSTRACTThe direct decomposition of NO (2NO → N2+02) has been carried out using an electrochemical membrane reactor composed of an yttria-stabilized zirconia (YSZ) disc deposited with Pd and Au metal films at reaction temperature of 773∼1023 K and applying voltage of 0∼1.8 V. N2 and O2 were continuously produced in the cathode and anode chambers, respectively. NO decomposition activity increased by applying electrical potential. It was clearly shown that the enhancement of the catalytic activity was due to electrochemical pumping, by which the surface oxygen species formed by the dissociation of NO were transported from cathode to anode through YSZ. By comparing the catalytic activity between Pd/YSZ/Au and Au/YSZ/Au systems, it is suggested that the NO decomposition occurs mainly on the Pd surface, and YSZ itself did not catalyze the reaction at lower temperature. The rate-determining step for the reaction was the adsorption of NO at 973 K, while at 773 K, the step was either a diffusion of O2- in YSZ or a migration of surface oxygen species on the Pd surface. The surface observation of Pd films by SEM showed that many microvoids were created throughout the Pd surface after the reaction. The creation of the microvoids results in an increase in the number of three-phase boundary sites, which will play an important role for the enhancement of the NO decomposition. Moreover, it was found that Pd/YSZ/Au resisted a serious degradation of the activity in the presence of O2 in the feed stream.

Surface oxygen species essential for the catalytic activity of Ce–M–Sn (M = Mn or Fe) in soot oxidation

2021 ◽  
Author(s):  
Meng Wang ◽  
Yan Zhang ◽  
Yunbo Yu ◽  
Wenpo Shan ◽  
Hong He
Keyword(s):  
Catalytic Activity ◽  
Transition Metal ◽  
Hydrothermal Method ◽  
Soot Oxidation ◽  
Oxygen Species ◽  
Surface Oxygen

Herein, transition metal (Mn and Fe)-doped Ce–Sn nanorod catalysts were successfully synthesized via a hydrothermal method.

A new three-phase heterocrystal catalysts and their superior treatment efficiency for tetracycline

2016 ◽  
Vol 10 (03) ◽  
pp. 1750015
Author(s):  
Feng-Rui Wang ◽  
Hui-Ping Sun ◽  
Yan Wang ◽  
Jin-Ku Liu ◽  
Yi Fang ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Band Structure ◽  
Antibiotic Residues ◽  
Treatment Efficiency ◽  
Electron Hole ◽  
Three Phase ◽  
Catalytic Material ◽  
Water Based ◽  
The Stability ◽  
Functional Components

An easy recyclable and interesting Ag3PO4@Pt@TiO2 (APTP) three-phase heterocrystal chains were self-assembled by the cohesive action and chemical construction of polyvinylpyrrolidone (PVP). We found that a new electron–hole transmission path has been built via the rematch of the band structure of Ag3PO4, Pt and TiO2 which extends the light absorption and promoted the electron–hole separation to treat the antibiotic residues in the water. Based on the thorough investigations, a new catalytic material was provided for antibiotics degradation. The catalytic activity of APTP toward the degradation of tetracycline solution was enhanced by 166.67% and the stability increased remarkably compared with pure Ag3PO4 through the integration of different functional components.

scholarly journals Gas phase synthesis of dimethyl carbonate from CO2 and CH3OH over Cu-Ni/AC. A kinetic study

2019 ◽  
pp. 88-99 ◽  
Author(s):  
Oscar Felipe Arbeláez-Pérez ◽  
Sara Dominguez Cardozo ◽  
Andrés Felipe Orrego-Romero ◽  
Aida Luz Villa Holguin ◽  
Felipe Bustamante Londoño
Keyword(s):  
Carbon Dioxide ◽  
Catalytic Activity ◽  
Activated Carbon ◽  
Gas Phase ◽  
Dimethyl Carbonate ◽  
Direct Synthesis ◽  
Dispersion Analysis ◽  
Molar Ratio ◽  
Rate Determining Step ◽  
Carbonate Formation

The catalytic activity for dimethyl carbonate formation from carbon dioxide and methanol over mono and bimetallic Cu:Ni supported on activated carbon is presented. Bimetallic catalysts exhibit higher catalytic activity than the monometallic samples, being Cu:Ni-2:1 (molar ratio) the best catalyst; X-Ray diffraction, transmission electron microscopy, and metal dispersion analysis provided insight into the improved activity. In situ FT-IR experiments were conducted to investigate the mechanism of formation of dimethyl carbonate from methanol and carbon dioxide over Cu-Ni:2-1. The kinetics of the direct synthesis of dimethyl carbonate in gas phase over Cu:Ni-2:1 supported on activated carbon catalyst was experimentally investigated at 12 bar and temperatures between 90 oC and 130 oC, varying the partial pressures of CO2 and methanol. Experimental kinetic data were consistent with a Langmuir–Hinshelwood model that included carbon dioxide and methanol adsorption on catalyst actives sites (Cu, Ni and Cu-Ni), and the reaction of adsorbed CO2 with methoxi species as the rate determining step. The estimated apparent activation energy was 94.2 kJ mol-1.

scholarly journals Volcano-Type Correlation between Particle Size and Catalytic Activity on Hydrodechlorination catalyzed by AuPd Nanoalloy

2020 ◽  
Author(s):  
Yuta Uetake ◽  
Sachi Mouri ◽  
Setsiri Haesuwannakij ◽  
Kazu Okumura ◽  
Hidehiro Sakurai
Keyword(s):  
Catalytic Activity ◽  
Metal Ion ◽  
Mixing Time ◽  
Metal Nanoparticle ◽  
Edge Structure ◽  
X Ray ◽  
Rate Determining Step ◽  
Transmission Electron ◽  
Random Alloy ◽  
X Ray Absorption

<div>Although changing the size of metal nanoparticle (NP) is a reasonable way to tune and/or enhance their catalytic activity, size-selective preparation of NP possessing random-alloy morphology has been challenging because of the differences in the ionization potential of each metal ion. This study demonstrates a time-controlled aggregation–stabilization method for a size-selective preparation of random alloy NPs composed of Au and Pd, which are stabilized by poly(<i>N</i>-vinyl-2-pyrrolidone) (PVP). By adjusting the mixing time in the presence of a small amount of PVP, the aggregation was induced to produce AuPd:PVP with sizes ranging between 1.2 and 8.2 nm at approximately 1 nm intervals. Transmission electron microscopy (TEM), powder X-ray diffraction (PXRD), and extended x-ray absorption fine structure (EXAFS) analyses clearly indicated the formation of various sizes of AuPd nanoalloys with almost the same morphology, and size-dependent catalytic activity was observed when hydrodechlorination of 4-choroanisole was performed using 2-propanol as a reducing agent. AuPd:PVP with a size of 3.1 nm exhibited the highest catalytic activity. A comparison of the absorption edges on x-ray absorption near edge structure (XANES) spectra suggested that the electronic state of the Au and Pd species correlated with their catalytic activity, presumably affecting the rate-determining step.</div><div> </div>

scholarly journals Review on antibiotics treatment by electrochemical membrane reactor

2021 ◽  
Vol 233 ◽  
pp. 01042
Author(s):  
Lei Chao ◽  
Feilong Chen ◽  
Yi Han ◽  
Yafeng Li
Keyword(s):  
Membrane Reactor ◽  
Membrane Filtration ◽  
Electrode Materials ◽  
Degradation Mechanism ◽  
Membrane Reactors ◽  
Membrane Electrode ◽  
Actual Application ◽  
Electrochemical Membrane Reactor ◽  
Antibiotic Degradation ◽  
The Impact

Lower consumption, higher efficiency, environmental protection, and reliability are the development trends for the treatment of antibiotic wastewater in future. To accomplish this, the electrochemical membrane reactor (ECMR) is developed by combining membrane filtration and electrochemical advanced oxidation technology. The device configuration and working mode of the electrochemical membrane reactor are introduced and compared. Besides, the principles of the removal of antibiotics by the reactor are explained with emphasis. Furthermore, the commonly used cathode and anode materials of the reactor in the current research are summarized, and the electrode materials are discussed. The effects of selection and modification on the elimination of antibiotics in the reactor and the impact are analysed. To address the limitations of electrochemical membrane reactors, this review proposes that more research should be done in the aspects of antibiotic degradation mechanism, reduction of membrane electrode R&D costs, and actual application of amplification devices.

Different Chilling-Induced Symptoms and the Underlying Oxidative Stress and Antioxidative Defense in the Exocarp and Mesocarp of Immature Sponge Gourd (Luffa cylindrica) Fruit

2021 ◽  
Author(s):  
Pichaya Chuenchom ◽  
Sompoch Noichinda ◽  
Kitti Bodhipadma ◽  
Chalermchai Wongs-Aree ◽  
David W. M. Leung
Keyword(s):  
Oxidative Stress ◽  
Defense Mechanisms ◽  
Considerable Increase ◽  
Chilling Injury ◽  
Oxygen Species ◽  
Antioxidative Defense ◽  
Sponge Gourd ◽  
Lower Temperature ◽  
High Level ◽  
The Relationship

Immature sponge gourd fruit is consumed as a vegetable with a limited shelf life. Although cold storage is a simple and powerful tool for maintaining postharvest fruit quality, storage at a low temperature may not be appropriate for vegetables as some chilling injury (CI) of the immature sponge gourd fruit may occur. Therefore, this research aimed to elucidate the relationship between CI, oxidative stress, and the antioxidative defense mechanisms in the exocarp and mesocarp of immature sponge gourd fruit. After storage at 5°C for 6 days, visual CI symptoms, including browning and surface pitting, were found in the peel (exocarp) but not in the mesocarp. There were, however, more dead cells (stained by Evans blue) in the mesocarp of the fruit stored at 5°C. There was a more considerable increase in the electrolyte leakage rate in both fruit tissues held at 5°C than 25°C. The CI was correlated with malondialdehyde (MDA) levels in the tissues. The MDA of fruit exocarp at 5°C was 1.6 fold higher than that at 25°C on day 6, while the lipoxygenase (LOX) activity in mesocarp was 50% higher in fruit stored at a lower temperature. The action of ascorbate peroxidase (APX) was high in the exocarp of the fruit stored at 5°C, but there appeared to be a continuous depletion of the co-substrate or ascorbic acid. In conclusion, the CI in the exocarp was mainly associated with a high level of reactive oxygen species (ROS). In contrast, the CI in the mesocarp appeared to be primarily associated with increased lipid peroxidation by the elevated LOX activity under cold stress compared to storage at 25°C.

Correlation Between Tunable Oxygen Defects in TiO2 Nanoflower and Its Photocatalytic Performance for the Degradation of Organic Waste

NANO ◽  
2020 ◽  
Vol 15 (02) ◽  
pp. 2050018
Author(s):  
Cai Chen ◽  
Han Zhang ◽  
Arshid M. Ali ◽  
Hui Zhang
Keyword(s):  
Catalytic Activity ◽  
Degradation Rate ◽  
Surface Defects ◽  
Hydrogen Reduction ◽  
Defect Concentration ◽  
Oxygen Defect ◽  
Surface Oxygen ◽  
Fixed Amount ◽  
Photo Catalytic Activity ◽  
Oxygen Defects

Oxygen defects of nanoflower TiO2 photo-catalyst was fabricated at the presence of hydrogen at different temperatures (100–600∘C) and the concentrations of oxygen defects were firstly quantitatively analyzed by hydrogen programmed temperature reduction techniques (H2-TPR). Total oxygen defect concentration and surface oxygen defect concentration were consistent with XPS and EPR results, respectively. Even at the hydrogen thermal temperature of 600∘C, the shape of TiO2 was still kept as nanoflower structure as characterized by SEM. However, the rutile and anatase coexist in the composition of crystal phase when hydrogen reduction temperature of the TiO2 catalyst reached 400∘C to 600∘C as proved by Raman and XRD results. TiO2 sample with oxygen defects shows excellent photo-catalytic activity for degradation of Direct Blue 78(DB) regardless of ultraviolet light (the maximum degradation rate achieved within 100[Formula: see text]min was 93.27%) or visible light (the maximum degradation rate achieved within 100[Formula: see text]min was 88.25%). The photo-catalytic activity seems to be highly correlated with the surface oxygen defects of TiO2 catalyst. With surface oxygen-defect concentrations increase, the degradation ability on DB was significantly enhanced, while bulk oxygen defects had negligible effect on the photo-catalytic activity. The enhanced photo-catalytic performance of TiO2 with a fixed amount of oxygen defects was attributed to the strong capturing capability of the photo-generated electrons. In addition, the surface defects could also improve the photo-catalytic reaction efficiency.

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