scholarly journals Base adsorption mechanism over zeolite catalysts at different Al contents probed by the tapered element oscillating microbalance (TEOM)

2018 ◽  
Vol 20 (39) ◽  
pp. 25357-25364
Author(s):  
Pierre Bräuer ◽  
Carmine D’Agostino
Keyword(s):  
Adsorption Mechanism ◽  
High Accuracy ◽  
Zeolite Catalysts ◽  
Probe Molecules ◽  
Tapered Element Oscillating Microbalance

The TEOM is able to quantify with high accuracy the extent of physisorption and chemisorption of base probe molecules over zeolite surfaces at different Al contents.

scholarly journals The acidic nature of “NMR-invisible” tri-coordinated framework aluminum species in zeolites

2019 ◽  
Vol 10 (43) ◽  
pp. 10159-10169 ◽  
Author(s):  
Shaohui Xin ◽  
Qiang Wang ◽  
Jun Xu ◽  
Yueying Chu ◽  
Pengfei Wang ◽  
...  
Keyword(s):  
Solid State ◽  
Nmr Spectroscopy ◽  
Solid State Nmr ◽  
Zeolite Catalysts ◽  
Probe Molecules ◽  
Solid State Nmr Spectroscopy ◽  
Acidic Nature ◽  
Insight Into

A unique insight into the acidic nature of the tri-coordinated framework aluminum (AlFR) in H-ZSM-5 zeolite catalysts has been provided using multi-nuclear and multi-dimensional solid-state NMR spectroscopy in conjunction with TMPO probe molecules.

Adsorption and Diffusion in HZSM-5 Zeolite Studied by an Oscillating Microbalance

1997 ◽  
Vol 62 (12) ◽  
pp. 1832-1842 ◽  
Author(s):  
Hans P. Rebo ◽  
De Chen ◽  
Marit S. A. Brownrigg ◽  
Kjell Moljord ◽  
Anders Holmen
Keyword(s):  
Gas Phase ◽  
High Sensitivity ◽  
Probe Molecules ◽  
Additional Mass ◽  
Transfer Resistance ◽  
Partial Pressures ◽  
Uptake Rates ◽  
Flow Through ◽  
Tapered Element Oscillating Microbalance ◽  
And Diffusion

A novel microbalance technique has been used to study diffusion and adsorption in a commercial HZSM-5 zeolite. This new technique uses an inertial microbalance TEOM (Tapered Element Oscillating Microbalance) to measure mass changes in the zeolite bed. Time resolution as short as 0.1 s, a flow-through design where all the probe molecules see the zeolite bed and high sensitivity allowing zeolite loadings down to a few milligrams are the three most important properties of the TEOM. The probe molecules studied were o-xylene, p-xylene and toluene which were introduced at 303, 373 or 473 K and at partial pressures in the range of 0.2-10 kPa. The inverse characteristic uptakes (D/L2), corrected (D0/L2) and steady-state (Dss/L2) diffusion times are reported. The thermodynamic correction used for D0/L2 calculations almost eliminated the concentration dependence of the diffusivities. The Dss/L2 values were found to be rather unaffected by both temperature (373-473 K) and concentration, suggesting a certain degree of unification for diffusivities. o-Xylene uptake rates in the TEOM were found to be significantly higher than in a gravimetric microbalance under identical conditions, probably as a result of additional mass transfer resistance other than intracrystalline diffusion caused by poor contact between the gas phase and the zeolite in a conventional gravimetric microbalance.

A New 1,000 kV Electron Microscope

1967 ◽  
Vol 25 ◽  
pp. 260-261
Author(s):  
M. Nishigaki ◽  
S. Katagiri ◽  
H. Kimura ◽  
B. Tadano
Keyword(s):  
Electron Microscope ◽  
High Voltage ◽  
Basic Research ◽  
Chromatic Aberration ◽  
High Accuracy ◽  
Biological Specimen ◽  
Voltage Electron ◽  
High Voltage Electron Microscope ◽  
High Voltage Electron

The high voltage electron microscope has many advantageous features in comparison with the ordinary electron microscope. They are a higher penetrating efficiency of the electron, low chromatic aberration, high accuracy of the selected area diffraction and so on. Thus, the high voltage electron microscope becomes an indispensable instrument for the metallurgical, polymer and biological specimen studies. The application of the instrument involves today not only basic research but routine survey in the various fields. Particularly for the latter purpose, the performance, maintenance and reliability of the microscope should be same as those of commercial ones. The authors completed a 500 kV electron microscope in 1964 and a 1,000 kV one in 1966 taking these points into consideration. The construction of our 1,000 kV electron microscope is described below.

Advances in ultramicrotomy for physical sciences applications

1993 ◽  
Vol 51 ◽  
pp. 710-711
Author(s):  
G. McMahon ◽  
T. Malis
Keyword(s):  
Particle Surface ◽  
Zeolite Catalysts ◽  
Physical Sciences ◽  
Pull Out ◽  
Large Particles ◽  
Novel Applications ◽  
Metal Wires ◽  
Frequent Problem ◽  
Specific Orientation ◽  
Diamond Knife

As with all techniques which are relatively new and therefore underutilized, diamond knife sectioning in the physical sciences continues to see both developments of the technique and novel applications.Technique Developments Development of specific orientation/embedding procedures for small pieces of awkward shape is exemplified by the work of Bradley et al on large, rather fragile particles of nuclear waste glass. At the same time, the frequent problem of pullout with large particles can be reduced by roughening of the particle surface, and a proven methodology using a commercial coupling agent developed for glasses has been utilized with good results on large zeolite catalysts. The same principle (using acid etches) should work for ceramic fibres or metal wires which may only partially pull out but result in unacceptably thick sections. Researchers from the life sciences continue to develop aspects of embedding media which may be applicable to certain cases in the physical sciences.

Application Of BIM-Technology In The Restoration Of Buildings

2020 ◽  
pp. 42-48
Keyword(s):  
Chinese Communist Party ◽  
Laser Scanning ◽  
High Accuracy ◽  
Information Environment ◽  
Information Modeling ◽  
Structural Scheme ◽  
Traditional Design ◽  
Information Interaction ◽  
Heritage Buildings ◽  
Effective Organization

The paper describes the main trends in the development of BIM technologies in the field of restoration and reconstruction of historical and cultural heritage buildings. The practical part of the paper presents the experience in using information modeling technologies when restoring the building, where the VI Congress of the Chinese Communist Party in Moscow took place. The use of laser scanning technologies made it possible to reproduce with high accuracy in the information model the original appearance of the building using Autodesk RevitR software. It is shown, how the use of information modeling technologies affects the duration of restoration process, taking into account the calculation of the structural scheme and bearing structures of the building, ensuring the identity of the decoration and the effective organization of electromechanical installation. Operating in a single BIM information environment makes it possible to continuously obtain reliable information on the project, which provides more effective information interaction and communication of participants compared to using traditional design methods.

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