Ho Thi H, Do Tuong Ha, Tong Hien Duy, Meijer Evert Jan, Trinh Thuat T
Laboratory for Computational Physics Institute for Computational Science and Artificial Intelligence, Van Lang University, Ho Chi Minh City 700000, Vietnam.
Faculty of Mechanical - Electrical and Computer Engineering School of Technology, Van Lang University, Ho Chi Minh City 700000, Vietnam.
J Phys Chem B. 2023 Sep 14;127(36):7748-7757. doi: 10.1021/acs.jpcb.3c04256. Epub 2023 Aug 30.
The comprehension of silicate oligomer formation during the initial stage of zeolite synthesis is of significant importance. In this study, we investigated the effect of chloride ions (Cl) on silicate oligomerization using molecular dynamics simulations with explicit water molecules. The results show that the presence of Cl increases the free energy barriers of all reactions compared to the case without the anion. The formation of the 4-ring structure has the lowest free energy barrier (73 kJ/mol), while the formation of the 3-ring structure has the highest barrier (98 kJ/mol) in the presence of Cl. These findings suggest that Cl suppresses the formation of 3-rings and favors the formation of larger oligomers in the process of zeolite synthesis. Our study provides important insights into the directing role of Cl in silicate oligomerization by regulating thermodynamic and kinetic parameters. An important point to consider is the impact of the anion on aqueous reactions, particularly in altering the hydrogen bond network around reactive species. These results also provide a basis for further studies of the formations of larger silicate oligomers in solution.
理解沸石合成初始阶段硅酸盐低聚物的形成具有重要意义。在本研究中，我们使用包含显式水分子的分子动力学模拟，研究了氯离子（Cl）对硅酸盐低聚作用的影响。结果表明，与不存在该阴离子的情况相比，Cl的存在增加了所有反应的自由能垒。在存在Cl的情况下，4元环结构的形成具有最低的自由能垒（73 kJ/mol），而3元环结构的形成具有最高的自由能垒（98 kJ/mol）。这些发现表明，在沸石合成过程中，Cl抑制了3元环的形成，有利于形成更大的低聚物。我们的研究通过调节热力学和动力学参数，为Cl在硅酸盐低聚作用中的导向作用提供了重要见解。需要考虑的一个重要点是阴离子对水相反应的影响，特别是在改变反应物种周围的氢键网络方面。这些结果也为进一步研究溶液中更大硅酸盐低聚物的形成提供了基础。
