The reactivity of NO3-type adsorbed species on the decomposition of nitrogen monoxide over copper/Y-zeolites

1998 ◽  
Vol 64 (1) ◽  
pp. 49-54 ◽  
Author(s):  
M. Shimokawabe ◽  
S. Sasaki ◽  
N. Takezawa
Keyword(s):  
Nitrogen Monoxide ◽  
Adsorbed Species ◽  
Y Zeolites

Formation, mobilité et réactivité d'espèces paramagnétiques adsorbées sur zéolithes H—Y irradiées. Une étude par résonance paramagnétique électronique

1976 ◽  
Vol 54 (11) ◽  
pp. 1678-1686 ◽  
Author(s):  
Jacques C. Vedrine ◽  
Jean Massardier ◽  
Antoine Abou-Kaïs
Keyword(s):  
Molecular Oxygen ◽  
Spin Density ◽  
Adsorbed Species ◽  
Y Zeolites ◽  
Γ Radiation ◽  
Adsorption Sites ◽  
Unpaired Spin ◽  
Original Approach ◽  
Adsorptive Properties ◽  
Monolayer Coverage

Use of γ radiation as an ionizing source has been successfully applied to an epr study of adsorption sites and of adsorbed species in the case of H—Y zeolites. Adsorption sites have appeared to be mainly oxygen nuclei from the lattice. It has been observed that molecular hydrogen neutralizes paramagnetic sites while molecular oxygen gives rise to O2−-type radicals which have nearly equal unpaired spin density on the two nuclei (43 and 57%). Carbon monoxide gives rise to a species assigned to C+O which reacts very easily at 77 K with molecular oxygen to yield an O2−-type species for which the spin density distribution is not equivalent on the two oxygen nuclei [Formula: see text] The nature and the mobility of OH• and NH2• radicals have been studied in detail. They arise from the ionization of physisorbed H2O and NH3, the better yield being obtained at a monolayer coverage. This study leads to an original approach to the study of the adsorptive properties of zeolites.

Statistical Processing and Correlations Between Concentrations of Some Atmospheric Pollutants in Suceava and Botosani Counties

2020 ◽  
Vol 71 (7) ◽  
pp. 175-186
Author(s):  
Doina Lutic ◽  
Danut-Gabriel Cozma
Keyword(s):  
Nitrogen Monoxide ◽  
Statistical Processing ◽  
Geographic Area ◽  
The Other ◽  
Atmospheric Pollutants ◽  
Climate Conditions ◽  
National Network ◽  
Different Seasons ◽  
Official Site ◽  
Social Wealth

The abundance of some pollutants from the air depend on the geographic area, the human activities intensity, the climate, the season and even on the hour within a day. The nitrogen oxides are the most abundant and most dangerous toxic species from the air, and these emissions are tightly connected to human polluting activities. Therefore, in our work, the first part is assigned for a wide literature search concerning the incidence of the keywords �nitrogen oxide� and searching the connections with other significant related terms and formulas, investigated by the researches worldwide. Then, a statistic approach was applied trying to correlate the values of the concentration in air of nitrogen monoxide, nitrogen dioxide, carbon monoxide, sulfur dioxide, benzene and particulate matter PM10, all of these being generated to a large extent from the exhaust gases from different automotives. The data were collected from the official site of the National Network of Air Quality Monitoring from Romania, and processed by statistical methods, using specific software and methods, in order to find significant differences between the pollutants concentrations values in two neighbor counties (Suceava and Botosani), with relatively similar climate conditions, but different social wealth. The findings of these statistical processing indicate that the PM10 values do not present significant differences between the two locations, neither the time within a day, while the other parameters exhibit distinctions between the values of the other pollutants concentrations in different seasons (summer and winter) and hourly intervals within a day (night, morning, afternoon and evening).

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

1987 ◽  
Vol 52 (7) ◽  
pp. 1701-1707 ◽  
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.

Aromatic Transformation in Fluidized Bed Reactors

2008 ◽  
Vol 73 (8-9) ◽  
pp. 1061-1088
Author(s):  
Sule Rabiu ◽  
Sulaiman Al-Khattaf
Keyword(s):  
Fluidized Bed ◽  
The Other ◽  
Fluidized Bed Reactors ◽  
Y Zeolite ◽  
Y Zeolites ◽  
Toluene Disproportionation ◽  
Xylene Isomerization ◽  
Toluene Methylation ◽  
Toluene Conversion ◽  
Medium Acidity

In this work three important aromatic transformations, namely: toluene disproportionation, toluene methylation and m-xylene isomerization, were investigated in a riser simulator which closely mimics the operation of commercial fluidized bed reactors. The transformations were studied over a ZSM-5 based catalyst with medium acidity of 0.23 mmol/g and a series of Y zeolites of acidities between 0.55 and 0.03 mmol/g. For pure toluene feed, it was observed that conversion over the ZSM-5 based catalyst and the weakly acidic Y zeolite (USY-1) was very low. However, with the highly acidic Y zeolite (H-Y), significant toluene conversion was observed with paring reaction more prominent than disproportionation. On the other hand, when toluene was alkylated with methanol, higher toluene conversions were achieved over both the ZSM-5 based and the weakly acidic USY-1 catalysts as compared to when pure toluene feed was used. In addition, p-xylene/o-xylene (P/O) ratios higher than the equilibrium values were obtained in the reaction product over both catalysts. Finally, for m-xylene isomerization it was found that m-xylene conversion increased initially as the acidity of the catalyst increased up to 0.1 mmol/g beyond which any further increase in acidity resulted in a slight decrease in the m-xylene conversion.

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