Effect of Counter Ions on the Silica Oligomerization Reaction

Trinh, Thuat T.; Jansen, Apj Tonek; Santen, Rutger A. van; VandeVondele, Joost; Meijer, Evert Jan

doi:10.1002/cphc.200900006

Cited by 50 publications

(114 citation statements)

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“…We also investigated possible reasons for increased reaction barriers. We found that direct coordination to the negatively charged oxygen, observed for other ions 22 was rare for sodium. A possible reason for this is that coordination to sodium leads to breaking of two hydrogen bonds for the negatively charged oxygen, making the coordination unfavorable.…”

Section: Discussionmentioning

confidence: 90%

“…They also studied the effect of lithium and ammonium ions on the formation of smaller silicic acid chains using the same method. 22 It was shown that cations increase the total reaction barrier and that the Si-O bond formation step is more affected than the water removal step. For the silica dimer formation, the cations were observed to directly coordinate to the reacting Si-O group during the first reaction step, explaining the increased barriers in these cases.…”

Section: 18mentioning

confidence: 99%

“…4 and Table 2 compare the total reaction barriers in the presence of Na + to previously calculated cases without any cation 20 and in the presence of Li + . 22 The difference between sodium and lithium is much larger than the error margin, while the difference between pure water and sodium is larger than the error margin only for dimer and trimer formations.…”

mentioning

confidence: 99%

“…5a, is rare for all of the three reactions. This type of coordination is common when Li + is used 22 instead of Na + and could explain the difference in the energy barriers for the two ions. Coordination to non-reacting Si-OH groups, see Fig.…”

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confidence: 99%

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Clarifying the role of sodium in the silica oligomerization reaction

Pavlova

Trinh

Santen

et al. 2013

Phys. Chem. Chem. Phys.

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115

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aSilica oligomerization is the key reaction in zeolite synthesis. NaOH is a common additive in the zeolite synthesis that decreases the reaction rate of smaller silica oligomers and also affects the final structure of the zeolite. Here we report a study of the role of sodium in the initial stages of silica oligomerization. We performed ab initio molecular dynamics simulations using ecplicit aqueous solution in order to obtain the free energy profile and study the behavior of sodium during the reaction. Our study confirms that sodium decreases the reaction rates of oligomerization for smaller silica chains.Analysis of the molecular dynamics trajectories shows that sodium does not increase the reaction barriers by direct coordination to the silica. However, sodium is often present in the second solvation shell of the reactive atoms. Correlation between sodium presence in the first or the second shell of the reactive oxygen and a decrease in hydrogen bonding for that oxygen was found for the first reaction step. Therefore, the presence of sodium could contribute to an increase in reaction barriers for silica oligomerization by some rearrangement of the hydrogen bond network of water solution around the reactants.

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Section: Discussionmentioning

confidence: 90%

Section: 18mentioning

confidence: 99%

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confidence: 99%

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confidence: 99%

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Clarifying the role of sodium in the silica oligomerization reaction

Pavlova

Trinh

Santen

et al. 2013

Phys. Chem. Chem. Phys.

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115

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“…46,47,49,50,53 For these calculations Car-Parrinello MD (CPMD) simulations were run, which are ideally suited to describe the dynamics of the water molecules. To capture fully the influence of water, the oligomerization reactions were studied using periodically repeated water boxes and an ab initio molecular dynamics (MD) approach.…”

Section: Review Articlementioning

confidence: 99%

Advances in theory and their application within the field of zeolite chemistry

et al. 2015

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Zeolites are versatile and fascinating materials which are vital for a wide range of industries, due to their unique structural and chemical properties, which are the basis of applications in gas separation, ion exchange and catalysis. Given their economic impact, there is a powerful incentive for smart design of new materials with enhanced functionalities to obtain the best material for a given application. Over the last decades, theoretical modeling has matured to a level that model guided design has become within reach. Major hurdles have been overcome to reach this point and almost all contemporary methods in computational materials chemistry are actively used in the field of modeling zeolite chemistry and applications. Integration of complementary modeling approaches is necessary to obtain reliable predictions and rationalizations from theory. A close synergy between experimentalists and theoreticians has led to a deep understanding of the complexity of the system at hand, but also allowed the identification of shortcomings in current theoretical approaches. Inspired by the importance of zeolite characterization which can now be performed at the single atom and single molecule level from experiment, computational spectroscopy has grown in importance in the last decade. In this review most of the currently available modeling tools are introduced and illustrated on the most challenging problems in zeolite science. Directions for future model developments will be given.

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Quantum Chemistry Methods

Sautet

2012

Characterization of Solid Materials and Heterogeneous Catalysts

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Effect of Counter Ions on the Silica Oligomerization Reaction

Cited by 50 publications

References 48 publications

Clarifying the role of sodium in the silica oligomerization reaction

Clarifying the role of sodium in the silica oligomerization reaction

Advances in theory and their application within the field of zeolite chemistry

Quantum Chemistry Methods

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