3.2.4 Sound absorption in nonassociated aliphatic hydrocarbons

2005 ◽  
pp. 170-173
Author(s):  
W. Schaaffs
Keyword(s):  
Sound Absorption ◽  
Aliphatic Hydrocarbons

Effect of Coating Thickness on Sound Absorption Property of Four Wood Species Commonly Used for Piano Soundboards

2020 ◽  
Vol 52 (1) ◽  
pp. 28-43 ◽  
Author(s):  
Wei Xu ◽  
Xiaoyang Fang ◽  
Jiatong Han ◽  
Zhihui Wu ◽  
Jilei Zhang
Keyword(s):  
Coating Thickness ◽  
Wood Species ◽  
Sound Absorption ◽  
Absorption Property

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.

Aromatization of C2-C6 Aliphatic Hydrocarbons on Copper-Containing ZSM-5 Zeolites

1992 ◽  
Vol 57 (12) ◽  
pp. 2553-2560
Author(s):  
Zdravka Popova ◽  
Katia Aristirova ◽  
Christo Dimitrov
Keyword(s):  
Copper Content ◽  
Acid Strength ◽  
The State ◽  
Aliphatic Hydrocarbons ◽  
Bronsted Acid ◽  
Ion Formation ◽  
Brönsted Acid ◽  
Wide Range ◽  
Carbenium Ion ◽  
Acid Centers

The aromatization of a wide range of model aliphatic and cycloaliphatic hydrocarbons (ethene, ethane, propene, n-hexane, 1-hexene, methylcyclopentane, cyclohexane, cyclohexene) on copper-containing NaZSM-5 and HZSM-5 zeolites has been investigated. It was established that the degree of aromatization is related to carbenium ion formation and depends on the acid strength and copper content of zeolite. Experiments with copper-containing samples reduced prior to use indicated the possibility to enhance the selectivity to aromatization. The change of the state of Cu2+ ions during catalytic experiments confirmed the assumption about participation of Cu0 simultaneously with the Bronsted acid centers in the dehydrogenation/hydrogenation steps.

Molecular orientation of liquid aliphatic hydrocarbons on the surface and at the interface with water

1989 ◽  
Vol 54 (12) ◽  
pp. 3171-3186 ◽  
Author(s):  
Jan Kloubek
Keyword(s):  
Free Energy ◽  
Surface Free Energy ◽  
Molecular Orientation ◽  
Phase Changes ◽  
Aliphatic Hydrocarbons ◽  
Water Molecules ◽  
Free Energies ◽  
Dispersion Component ◽  
System Water ◽  
Orientation Of Molecules

The validity of the Fowkes theory for the interaction of dispersion forces at interfaces was inspected for the system water-aliphatic hydrocarbons with 5 to 16 C atoms. The obtained results lead to the conclusion that the hydrocarbon molecules cannot lie in a parallel position or be randomly arranged on the surface but that orientation of molecules increases there the ration of CH3 to CH2 groups with respect to that in the bulk. This ratio is changed at the interface with water so that the surface free energy of the hydrocarbon, γH, rises to a higher value, γ’H, which is effective in the interaction with water molecules. Not only the orientation of molecules depends on the adjoining phase and on the temperature but also the density of hydrocarbons on the surface of the liquid phase changes. It is lower than in the bulk and at the interface with water. Moreover, the volume occupied by the CH3 group increases on the surface more than that of the CH2 group. The dispersion component of the surface free energy of water, γdW = 19.09 mJ/m2, the non-dispersion component, γnW = 53.66 mJ/m2, and the surface free energies of the CH2 and CH3 groups, γ(CH2) = 32.94 mJ/m2 and γ(CH3) = 15.87 mJ/m2, were determined at 20 °C. The dependence of these values on the temperature in the range 15-40 °C was also evaluated.

Distribution and sources of aliphatic hydrocarbons in surface sediments of Sergipe River estuarine system

2012 ◽  
Vol 64 (8) ◽  
pp. 1721-1725 ◽  
Author(s):  
Manoel B. Lima ◽  
Elaine A. Feitosa ◽  
Elissandro S. Emídio ◽  
Haroldo S. Dórea ◽  
Marcelo R. Alexandre
Keyword(s):  
Surface Sediments ◽  
Aliphatic Hydrocarbons ◽  
Estuarine System ◽  
River Estuarine
Sign in / Sign up

Export Citation Format

Share Document