The Role of Water Loading and Germanium Content in Germanosilicate Hydrolysis

Author(s):  
Mengting Jin ◽  
Ondřej Veselý ◽  
Christopher Heard ◽  
Martin Kubů ◽  
Petr Nachtigal ◽  
...  

New zeolitic frameworks can be prepared through the Assembly-Disassembly-Organisation-Reassembly (ADOR) process by exploiting the lability of Ge-O bonds in germanosilicate zeolites to control their hydrolysis. In the disassembly step, two key factors are water and germanium content, but their exact roles remain unknown. Nevertheless, we combined experimental water-vapor adsorption with first principles simulations to identify the mechanism of germanosilicate zeolite disassembly. The results showed that water vapor adsorption on <b>UTL</b> germanosilicate proceeds in reversible (at low partial pressures) and irreversible (at higher partial pressures) modes. Based on our ab initio molecular dynamics simulations, we related these two modes to weak physisorption at low water loading and to reactive transformations at high water loading, via collective mechanisms requiring high local water concentrations. This bimodal behavior also depends on the germanium content as high Ge-content further decreases <b>UTL</b> hydrolytic stability by opening up yet another low-energy disassembly pathway at high water loading. Overall, we discovered, verified and explained the mechanisms of <b>UTL</b> disassembly and its factors. These findings will likely be generalized to other ADORable germanosilicate zeolites and help to find the optimal protocol for the synthesis of new zeolites.

2021 ◽  
Author(s):  
Mengting Jin ◽  
Ondřej Veselý ◽  
Christopher Heard ◽  
Martin Kubů ◽  
Petr Nachtigal ◽  
...  

New zeolitic frameworks can be prepared through the Assembly-Disassembly-Organisation-Reassembly (ADOR) process by exploiting the lability of Ge-O bonds in germanosilicate zeolites to control their hydrolysis. In the disassembly step, two key factors are water and germanium content, but their exact roles remain unknown. Nevertheless, we combined experimental water-vapor adsorption with first principles simulations to identify the mechanism of germanosilicate zeolite disassembly. The results showed that water vapor adsorption on <b>UTL</b> germanosilicate proceeds in reversible (at low partial pressures) and irreversible (at higher partial pressures) modes. Based on our ab initio molecular dynamics simulations, we related these two modes to weak physisorption at low water loading and to reactive transformations at high water loading, via collective mechanisms requiring high local water concentrations. This bimodal behavior also depends on the germanium content as high Ge-content further decreases <b>UTL</b> hydrolytic stability by opening up yet another low-energy disassembly pathway at high water loading. Overall, we discovered, verified and explained the mechanisms of <b>UTL</b> disassembly and its factors. These findings will likely be generalized to other ADORable germanosilicate zeolites and help to find the optimal protocol for the synthesis of new zeolites.


2020 ◽  
Vol 7 (20) ◽  
pp. 3919-3924
Author(s):  
Zeng-Kui Zhu ◽  
Li-Dan Lin ◽  
Jing Zhang ◽  
Xin-Xiong Li ◽  
Yan-Qiong Sun ◽  
...  

A rare 3D porous chiral polyoxoniobate framework has been constructed from two types of isomeric {Cu(en)2KNb24O72} clusters with a 4-connected neb-type topology. This compound exhibits proton conduction and high water vapor adsorption properties.


2021 ◽  
Vol 60 (3) ◽  
pp. 1922-1929
Author(s):  
Guo-Li Yang ◽  
Xue-Jing Che ◽  
Sheng-Li Hou ◽  
Chun-Shuai Cao ◽  
Bin Zhao

Author(s):  
Aasif A. Dabbawala ◽  
K. Suresh kumar Reddy ◽  
Hemant Mittal ◽  
Yasser Al Wahedi ◽  
Balasubramanian V. Vaithilingam ◽  
...  

Fuel ◽  
2017 ◽  
Vol 197 ◽  
pp. 326-333 ◽  
Author(s):  
Cheng Wang ◽  
Qi Liu ◽  
Douglas G. Ivey ◽  
Thomas H. Etsell

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