Effect of Li, Na, K and Cs on Vacuum Decomposition of Tetraammineplatinum(II) in Zeolites. Catalytic Activity in CO + NO Reaction

Jana Nováková; Libor Brabec; Ludmila Kubelková

doi:10.1135/cccc19950428

Effect of Li, Na, K and Cs on Vacuum Decomposition of Tetraammineplatinum(II) in Zeolites. Catalytic Activity in CO + NO Reaction

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19950428 ◽

1995 ◽

Vol 60 (3) ◽

pp. 428-442 ◽

Cited By ~ 3

Author(s):

Jana Nováková ◽

Libor Brabec ◽

Ludmila Kubelková

Keyword(s):

Catalytic Activity ◽

Decomposition Rate ◽

Reaction Rate ◽

Hydrogen Reduction ◽

Pt Catalyst ◽

Y Zeolites ◽

Oxygen Layer ◽

Zeolite Structure ◽

X Zeolites ◽

Vacuum Decomposition

[Pt(NH3)4]2+ ions were exchanged for alkali (Li, Na, K and Cs) in -X and -Y zeolites and decomposed in vacuum. TPR after this decomposition showed that autoreduction accompanying this process reduced roughly 2/3 of all Pt2+ to Pt0. The extent of the autoreduction rose with the ammonia pressure over the zeolite. The decomposition rate increased with increasing electropositivity of the alkali ion and this effect completely overlapped that of the zeolite structure. The CO + NO reaction rate also increased from Li to Cs, but -X zeolites were substantially more active than the -Y ones. Oxygen layer on the resulting Pt catalyst affected positively the reaction rate. The dispersion of Pt particles was relatively low, when compared to that obtained by decomposition of the Pt tetraammine complex in oxygen followed by hydrogen reduction. However, the reaction rate was higher.

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Transformation of methanol to hydrocarbons over Y zeolites with varying Si/Al ratio

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19871701 ◽

1987 ◽

Vol 52 (7) ◽

pp. 1701-1707 ◽

Cited By ~ 1

Author(s):

Miloslav Křivánek ◽

Nguyen Thiet Dung ◽

Pavel Jírů

Keyword(s):

Catalytic Activity ◽

Reaction Time ◽

Coke Formation ◽

Aliphatic Hydrocarbons ◽

Y Zeolite ◽

Y Zeolites ◽

Methanol To Hydrocarbons

The catalytic activity of Na, H-Y zeolite samples with a varying Si/Al ratio (2·5 to 20) in the transformation of methanol was determined. The amounts of formed individual aliphatic hydrocarbons as function of reaction time were correlated with the amount of Bronsted and Lewis centres on the catalysts. The effect of coke formation on the over-all course of the reaction has been demonstrated.

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Oxidative decarboxylation of isocitric acid in the presence of montmorillonite

Clay Minerals ◽

10.1180/claymin.1990.025.1.04 ◽

1990 ◽

Vol 25 (1) ◽

pp. 27-37 ◽

Cited By ~ 8

Author(s):

A. Naidja ◽

B. Siffert

Keyword(s):

Catalytic Activity ◽

Reaction Mechanism ◽

Nicotinamide Adenine Dinucleotide ◽

Reaction Rate ◽

Nicotinamide Adenine Dinucleotide Phosphate ◽

Oxidative Decarboxylation ◽

Enzymatic System ◽

Exchangeable Cation ◽

Isocitric Acid ◽

Dehydrogenase Enzyme

AbstractIsocitric acid oxidative decarboxylation was realized in the absence and in the presence of homoionic Na+-, Mn2+-, and Cu2+-montmorillonite. The catalytic activity of the clay depends upon the nature of the interlayer exchangeable cation. Isocitric acid is transformed into α-ketoglutaric acid under the action of the clay mineral saturated with Na+ cations which do not form a complex with the isocitrate anion. Nevertheless, the reaction rate is very much lower than in the presence of the enzymatic system (isocitrate dehydrogenase enzyme and nicotinamide adenine dinucleotide phosphate coenzyme). The reaction mechanism in the presence of clay is given showing the different steps of the transformation.

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

NANO ◽

10.1142/s1793292020500186 ◽

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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Catalytic activity of differently prepared, fully exchanged lanthanum Y zeolites

Zeolites ◽

10.1016/s0144-2449(88)80312-9 ◽

1988 ◽

Vol 8 (3) ◽

pp. 228-231 ◽

Cited By ~ 12

Author(s):

David Keir ◽

Edward F.T. Lee ◽

Lovat V.C. Rees

Keyword(s):

Catalytic Activity ◽

Y Zeolites

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ChemInform Abstract: CHARACTERIZATION AND CATALYTIC ACTIVITY OF NICKEL(2+)-EXCHANGED X AND Y ZEOLITES. II. REDUCIBILITY OF NI2+ BY LOW-MOLECULAR-WEIGHT OLEFINS AND THE DIMERIZATION ACTIVITY OF THE NI2+-ZEOLITES

Chemischer Informationsdienst ◽

10.1002/chin.198532031 ◽

1985 ◽

Vol 16 (32) ◽

Author(s):

A. BARTH ◽

J. HOFFMANN

Keyword(s):

Molecular Weight ◽

Catalytic Activity ◽

Low Molecular Weight ◽

Y Zeolites ◽

Abstract Characterization

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Warped graphitic layers generated by oxidation of fullerene extraction residue and its oxygen reduction catalytic activity

Beilstein Journal of Nanotechnology ◽

10.3762/bjnano.10.137 ◽

2019 ◽

Vol 10 ◽

pp. 1391-1400 ◽

Cited By ~ 4

Author(s):

Machiko Takigami ◽

Rieko Kobayashi ◽

Takafumi Ishii ◽

Yasuo Imashiro ◽

Jun-ichi Ozaki

Keyword(s):

Catalytic Activity ◽

Oxygen Reduction ◽

Active Sites ◽

Reduction Reaction ◽

Oxidation Time ◽

Pt Catalyst ◽

Oxidation Treatment ◽

Orr Activity ◽

Temperature Programmed ◽

Carbon Catalysts

Carbon-based oxygen reduction reaction (ORR) catalysts are regarded as a promising candidate to replace the currently used Pt catalyst in polymer electrolyte fuel cells (PEFCs); however, the active sites remain under discussion. We predicted that warped graphitic layers (WGLs) are responsible for the ORR catalytic activity in some carbon catalysts (i.e., carbon alloy catalysts (CACs)). To prove our assumption, we needed to use WGLs consisting of carbon materials, but without any extrinsic catalytic elements, such as nitrogen, iron, or cobalt, which effectively enhance ORR activity. The present study employed a fullerene extraction residue as a starting material to construct WGLs. The oxidation of the material at 600 °C exposed the WGLs by removing the surrounding amorphous moieties. Transmission electron microscopy (TEM) observations revealed the formation of WGLs by oxidation treatment at 600 °C in an O2/N2 stream. Extending the oxidation time increased the purity of the WGL phase, but also simultaneously increased the concentration of oxygen-containing surface functional groups as monitored by temperature programmed desorption (TPD). The specific ORR activity increased with oxidation up to 1 h and then decreased with the intensive oxidation treatment. Correlations between the specific ORR activity and other parameters confirmed that the development of the WGL and the increase in the O/C ratio are the competing factors determining specific ORR activity. These results explain the maximum specific ORR activity after 1 h of oxidation time. WGLs were found to lower the heat of adsorption for O2 and to increase the occurrence of heterogeneous electron transfer.

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Layer-Like Zeolite X as Catalyst in a Knoevenagel Condensation: The Effect of Different Preparation Pathways and Cation Exchange

Catalysts ◽

10.3390/catal11040474 ◽

2021 ◽

Vol 11 (4) ◽

pp. 474

Author(s):

Jan-Paul Grass ◽

Katharina Klühspies ◽

Bastian Reiprich ◽

Wilhelm Schwieger ◽

Alexandra Inayat

Keyword(s):

Catalytic Activity ◽

Reaction Rate ◽

Knoevenagel Condensation ◽

Ethyl Cyanoacetate ◽

Reaction Rates ◽

Initial Reaction Rate ◽

Comparative Investigation ◽

Morphological Properties ◽

Initial Reaction ◽

Zeolite X

This study is dedicated to the comparative investigation of the catalytic activity of layer-like Faujasite-type (FAU) zeolite X obtained from three different synthesis routes (additive-free route, Li2CO3 route, and TPOAC route) in a liquid-phase Knoevenagel condensation of benzaldehyde and ethyl cyanoacetate to ethyl trans-α-cyanocinnamate. It is shown that the charge-balancing cations (Na+ and K+) and the morphological properties have a strong influence on the apparent reaction rate and degree of conversion. The highest initial reaction rate could be found for the layer-like zeolite X synthesised by the additive-free route in the potassium form. In most cases, the potassium-exchanged zeolites enabled higher maximum conversions and higher reaction rates compared to the zeolite X catalysts in sodium form. However, very thin crystal plates (below 100 nm thickness), similar to those obtained in the presence of TPOAC, did not withstand the multiple aqueous ion exchange procedure, with the remaining coarse crystals facilitating less enhancement of the catalytic activity.

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A facile Pt catalyst regeneration process significantly improves the catalytic activity of Pt–organic composites for the O2 reduction reaction

Chemical Communications ◽

10.1039/c5cc03530a ◽

2015 ◽

Vol 51 (60) ◽

pp. 12052-12055 ◽

Cited By ~ 5

Author(s):

Jing-Fang Huang ◽

Wen-Yu Chen

Keyword(s):

Catalytic Activity ◽

Size Effect ◽

Catalytic Performance ◽

Reduction Reaction ◽

Pt Catalyst ◽

O2 Reduction ◽

Organic Composites ◽

Acidic Conditions ◽

Nano Size ◽

Complexation Ability

Combination of the “nano-size” effect and Cl− complexation ability causes massive electrodissolution of Pt under acidic conditions to promote the regeneration of Pt–organic composites and to significantly improve the catalytic performance of the O2 reduction reaction.

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