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In the liquid phase of heterogeneous catalysis, solvent plays an important role and governs the kinetics and thermodynamics of a reaction. Although it is often difficult to quantify the role of the solvent, it becomes particularly challenging when a zeolite is used as the catalyst. This difficulty arises from the complex nature of the liquid/zeolite interface and the different solvation environments around catalytically active sites. Here, we use ab initio molecular dynamics simulations to probe the local solvation structure and dynamics of methanol and water over MWW zeolite nanosheets with varying Brønsted acidity. We find that the zeolite framework and the number and location of the acid sites in the zeolite influence the structure and dynamics of the solvent. In particular, methanol is more likely to be in the vicinity of the aluminum (Al3+) at the T4 site than at T1 due to easy accessibility. The methanol oxygen binds strongly to the Al at the T4 site, weakening the Al–O for the bridging acid site, which results in the formation of the silanol group, significantly reducing the acidity of the site. The behavior of methanol is in direct contrast to that of water, where protons can easily propagate from the zeolite to the solvent molecules regardless of the acid site location. Our work provides molecular-level insights into how solvent interacts with zeolite surfaces, leading to an improved understanding of the catalytic site in the MWW zeolite nanosheet. [ABSTRACT FROM AUTHOR]

Lignin as a potential renewable source of biofuels, chemicals, and other value-added products has gained much attention. However, the complexity of lignin structure poses a significant challenge for developing efficient valorization techniques. As most processes involve solvothermal conditions to minimize energy cost, lignin depolymerization is governed by reaction conditions (temperature and pressure) and solvents. In this work, binding of β–O–4 linkage consisting lignin dimers on MWW two-dimensional (2D) zeolite is investigated using periodic density functional theory. Furthermore, the effect of different terminated surfaces (H:OH% = 100:0; 50:50; 0:100%), different temperatures (323, 353, 373 K), and different solvents (water and methanol) on the binding modes is quantified. Our work shows that in the gas phase the binding strength increases 10–15 kcal/mol upon increasing the number of hydroxyl groups on the surface. Also, the phenolic dimer binds more strongly than the nonphenolic dimer, and the binding strength of model compounds increases in the presence of the solvent. Analysis of structural changes in the presence of the solvent reveals that the aromatic rings are parallel to the zeolite surface and primary interaction with zeolite is through the hydroxyl groups near the β–O–4 linkage. Furthermore, while the solvation energy decreases with increasing temperature, the opposite trend is observed for the binding energy with the surface. [ABSTRACT FROM AUTHOR]