Network Dynamics and Species Exchange Processes in Aluminophosphate Glasses: An in situ High Temperature Magic Angle Spinning NMR View

2009 ◽  
Vol 113 (2) ◽  
pp. 416-425 ◽  
Author(s):  
Sebastian Wegner ◽  
Leo van Wüllen ◽  
Gregory Tricot
Keyword(s):  
High Temperature ◽  
Network Dynamics ◽  
Magic Angle Spinning ◽  
Magic Angle ◽  
Exchange Processes ◽  
Angle Spinning ◽  
Aluminophosphate Glasses

Development and Application of In Situ High-Temperature, High-Pressure Magic Angle Spinning NMR

2018 ◽  
pp. 1073-1091 ◽  
Author(s):  
Nicholas R. Jaegers ◽  
Mary Y. Hu ◽  
David W. Hoyt ◽  
Yong Wang ◽  
Jian Zhi Hu
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Magic Angle Spinning ◽  
Magic Angle ◽  
Angle Spinning ◽  
High Temperature High Pressure

scholarly journals Introduction of Al into the HPM-1 Framework by In Situ Generated Seeds as an Alternative Methodology

2018 ◽  
Vol 8 (9) ◽  
pp. 1634 ◽  
Author(s):  
Paloma Vinaches ◽  
Alex Rojas ◽  
Ana de Alencar ◽  
Enrique Rodríguez-Castellón ◽  
Tiago Braga ◽  
...  
Keyword(s):  
Textural Properties ◽  
Magic Angle Spinning ◽  
Ethanol Conversion ◽  
Magic Angle ◽  
Pure Silica ◽  
Acidic Sites ◽  
Alternative Methodology ◽  
Angle Spinning ◽  
Zeolitic Framework

An alternative method for the introduction of aluminum into the STW zeolitic framework is presented. HPM-1, a chiral STW zeolite with helical pores, was synthesized in the pure silica form, and an aluminum source was added by in situ generated seeds. Displacements of the peak positions in the Al samples were found in the X-ray diffractograms, indicating the possible incorporation of the heteroatom into the framework. Using an analysis of the 29Si and 27Al magic-angle spinning nuclear magnetic resonance (MAS NMR) spectra, we concluded that the aluminum was effectively introduced into the framework. The (AlTETRAHEDRAL/AlOCTAHEDRAL) ratio and its textural properties were studied to explain the catalytic ethanol conversion results at medium temperatures. The sample with the lowest Si/Al ratio showed the best results due to its higher surface area and pore volume, in comparison to those observed for the sample with the highest Si/Al ratio, and due to its higher bulk tetrahedral aluminum content, in comparison to the intermediate Si/Al ratio sample. All catalysts were selective to ethylene and diethyl ether, confirming the presence of acidic sites.

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