Ni and Cu Incorporated Mesoporous Nanocomposite Catalytic Materials

2008 ◽  
Vol 8 (2) ◽  
pp. 549-556 ◽  
Author(s):  
Asli Nalbant ◽  
Timur Dogu ◽  
Suna Balci
Keyword(s):  
Pore Size ◽  
Surface Area ◽  
Atomic Ratio ◽  
Nanocomposite Materials ◽  
Size Distributions ◽  
Hydrothermal Route ◽  
Average Pore ◽  
Pore Size Distributions ◽  
Xrd Patterns ◽  
Mcm 41

Nickel and copper incorporated MCM-41-like mesoporous nanocomposite materials prepared by the direct hydrothermal synthesis and the impregnation procedures showed highly attractive pore structure and surface area results for catalytic applications. The XRD patterns showed that characteristic MCM-41 structure was preserved for the materials synthesized following an impregnation procedure before the calcination step. The surface area of the Cu impregnated material with a quite high Cu/Si atomic ratio (0.19) was 631 m2/g. Very narrow pore size distributions with an average pore diameter of about 2.7 nm were obtained as a result of plugging of some of the smaller pores by Cu nanoballs. For lower metal to Si ratios (for instance for Ni/Si = 0.06) much higher surface area values (1130 m2/g) were obtained. In the case of nanocomposite materials synthesized by the direct hydrothermal route, MCM-41 structure was not destroyed for samples containing metal to Si atomic ratios as high as 0.12. In the case of materials containing Cu/Si and Ni/Si ratios over 0.2 wider pore size distributions and some decrease of surface area were observed.

Influence of Atmospheric Gases Present in the Pores of MCM-41 on Lifetime of Ortho-Positronium

2010 ◽  
Vol 666 ◽  
pp. 123-128 ◽  
Author(s):  
Radosław Zaleski ◽  
Michał Sokół
Keyword(s):  
Porous Material ◽  
Pore Size ◽  
Reasonable Agreement ◽  
Size Distributions ◽  
Spectroscopy Data ◽  
Atmospheric Gases ◽  
Positron Annihilation Lifetime ◽  
Pore Size Distributions ◽  
Mcm 41 ◽  
Quenching By Oxygen

The modification of the extended Tao-Eldrup model accounting ortho-positronium quenching in air is presented. Taking into account quenching by oxygen molecules adsorbed on the surface of porous material gives reasonable agreement between results of the model and the experimental positron annihilation lifetime spectroscopy data. Pore size distributions calculated using this model from the spectra for MCM 41 mesoporous sieve obtained in air, oxygen or vacuum are compared and discussed taking into account effect of ortho-positronium migration from small open pores to the larger ones. The rates of ortho-positronium quenching by air (47.2 µs-1 MPa 1), oxygen (220 µs-1 MPa-1) or nitrogen (1.7 µs-1 MPa-1) obtained from pressure dependences of the lifetimes observed in MCM 41 agree reasonably with the experimental results of other authors, if the correction for oxygen adsorbed on the surface is applied.

scholarly journals Comparison of Nitrogen Adsorption and Mercury Penetration Results. Pore Size Distributions for a Series of Mo-A12O3 Catalysis with Increasing MoO3 Content

1987 ◽  
Vol 4 (1-2) ◽  
pp. 87-104 ◽  
Author(s):  
Bruce D Adkins ◽  
Jill B. Heink ◽  
Burtron H. Davis
Keyword(s):  
Pore Size ◽  
Surface Area ◽  
Three Dimensional ◽  
Nitrogen Adsorption ◽  
Bet Surface Area ◽  
Size Distributions ◽  
Electron Microscopic ◽  
Pore Size Distributions ◽  
Electron Microscopic Data ◽  
Penetration Data

Scanning electron microscopic data, X-ray diffraction patterns and porosity measurements are consistent with a structure for an Mo-A12O3 catalyst series containing a single surface layer of Mo up to the point where the Mo loadings exceed the amount required for a monolayer. For greater Mo loadings than required for a monolayer, three dimensional orthorhombic MoO3 is also present. The cumulative pore volume, on an alumina basis, does not appear to be significantly altered by MoO3 loadings up to about 15 wt.%. The BET surface area, on an alumina basis, remains constant with Mo loading. However, the apparent surface area calculated from mercury penetration data decreases with Mo loading. For these materials with cylindrical pores, the Broekhoff-deBoer model for the calculation of pore size distributions produced closer agreement to the mercury penetration pore size distribution. This is in contrast to materials composed of nonporous spheres where the Broekhoff-deBoer model provided poorer agreement to mercury penetration results than either the Cohan or a packed sphere model. The results show that, within a factor of two the pore size distributions calculated from nitrogen adsorption and mercury penetration data are comparable.

Determination of Pore Size Distributions in Nano-Porous Thin Films from Small Angle Scattering

2003 ◽  
Vol 766 ◽  
Author(s):  
Barry J. Bauer ◽  
Ronald C. Hedden ◽  
Hae-Jeong Lee ◽  
Christopher L. Soles ◽  
Da-Wei Liu
Keyword(s):  
Pore Size ◽  
Small Angle ◽  
Length Distribution ◽  
Dielectric Constants ◽  
Scattering Data ◽  
Size Distributions ◽  
Average Pore ◽  
Pore Size Distributions ◽  
Phase Size

AbstractSmall angle neutron and x-ray scattering (SANS, SAXS) are powerful tools in determination of the pore size and content of nano-porous materials with low dielectric constants (low-k) that are being developed as interlevel dielectrics. Several models have been previously applied to fit the scattering data in order to extract information on the average pore and/or matrix size. A new method has been developed to provide information on the size distributions of the pore and matrix phases based on the “chord length distribution” introduced by Tchoubar and Mering. Examples are given of scattering from samples that have size distributions that are narrower and broader than the random distribution typical of scattering described by Debye, Anderson, and Brumberger. An example of fitting SANS data to a phase size distribution is given.

Porous Silica Nanomaterial Derived from Organic Waste Rice Husk as Highly Potential Drug Delivery Material

2019 ◽  
Vol 964 ◽  
pp. 88-96
Author(s):  
Hariyati Purwaningsih ◽  
Slamet Raharjo ◽  
Vania Mitha Pratiwi ◽  
Diah Susanti ◽  
Agung Purniawan
Keyword(s):  
Mesoporous Silica ◽  
Pore Size ◽  
Surface Area ◽  
Hydrothermal Treatment ◽  
Rice Husk ◽  
Average Pore Size ◽  
Sol Gel ◽  
Average Pore ◽  
Hydrothermal Temperature ◽  
Mcm 41

Rice became the main product of agriculture in agrarian countries including Indonesia. Rice husk is a waste of rice as one of the largest silica producers. Silica from rice husks can be used as a source of silica in the manufacture of sodium silicate as an alternative to the formation of mesoporous silica at a low price. In this research, the characterization of mesoporous silica nanoparticle (MSN) MCM-41 from rice husk (rice husk) with sol-gel method followed by hydrothermal treatment. Silica extraction was performed by titrating sodium silica using HCl method until the gel was formed. The mesoporous synthesis was performed with the addition of CTAB. The titration is then carried out using a solution of acetic acid. XRD shows silica with an amorphous structure. The FTIR results show that extraction silica and MSN MCM-41 contain pure silica displayed with Si-O-Si functional groups in the sample. The SEM results show MSN MCM-41 images such as a coral-like structure of agglomerated silica and the higher temperature hydrothermal treatment then it would be the more large size of particles. The material has a hexagonal pore structure such as a honeycomb as characteristic of MCM-41 with a pore size of 2.535 nm which includes mesoporous material. The result of nitrogen adsorption-desorption isotherms shows lower hydrothermal temperature will increase the specific surface area and decrease average pore size, where the best result with surface area value is 825.365 m2/gr and average pore size is 6.10426 nm obtained from process hydrothermal at 85°C.

The Effect of Pyrolysis Temperature and Formulation on Pore Size Distribution and Surfacearea of Carbon Aerogels

1992 ◽  
Vol 270 ◽  
Author(s):  
S.S. Hulsey ◽  
C.T. Alviso ◽  
F.M. Kong ◽  
R.W. Pekala
Keyword(s):  
Pore Size ◽  
Surface Area ◽  
Pyrolysis Temperature ◽  
Bet Surface Area ◽  
Vitreous Carbon ◽  
Basic Medium ◽  
Carbon Aerogels ◽  
Size Distributions ◽  
Structure Property ◽  
Pore Size Distributions

ABSTRACTRecently we reported the chemistry-structure-property relationships of organic aerogels, which are synthesized by the polycondensation of resorcinol and formaldehyde in a slightly basic medium, followed by supercritical drying. These materials can be pyrolyzed in an inert atmosphere to form vitreous carbon aerogels. As measured by gas adsorption techniques, the BET surface area and pore size distributions of micro and meso pores of the carbon aerogels are affected both by the pyrolysis temperature and the formulation. Definite trends are observed in our preliminary measurements; for example, the surface area decreases with increasing pyrolysis temperature until a plateau is reached at about 900°C. This paper explores the effects of pyrolysis temperature and aerogel density on the BET surface area and pore size distributions.

Controlling pore size distributions of MCM-41 by direct synthesis

1996 ◽  
Vol 7 (4) ◽  
pp. 173-185 ◽  
Author(s):  
Chih Ning Wu ◽  
Tz Sheng Tsai ◽  
Chyan Neng Liao ◽  
Kuei Jung Chao
Keyword(s):  
Pore Size ◽  
Direct Synthesis ◽  
Size Distributions ◽  
Pore Size Distributions ◽  
Mcm 41
Sign in / Sign up

Export Citation Format

Share Document