Effect of Solvent on the Interaction of Lignin with Zeolite Nanosheet in the Condensed

Lignin is the essential building block of lignocellulosic biomass, an excellent renewable source of different aromatic monomers for the polymer and biofuel industry. The depolymerization of lignin into value-added chemicals and fuels through the catalytic process poses a significant challenge due to the complex structure of lignin. Understanding lignin's conformational diversity and dynamics in the liquid phase is crucial for designing an effective depolymerization process. Here, we conducted all-atom molecular dynamics simulations to understand the conformation and dynamics of softwood lignin on the all-silica zeolite nanosheet based on the MFI topology in a binary mixture of water-methanol at three different molar compositions (0%, 50%, 100% methanol). We observed that methanol-surface interaction is stronger than water-surface, and methanol readily diffused into the MFI core. Lignin and surface contact decreases with increasing methanol composition due to higher solubility and dynamics. Lignin dynamics on the surface in neat water is an order of magnitude smaller than methanol. We also found that lignin adopts a slightly extended conformation when it stays on the surface than in the bulk solution phase for the pure water case, whereas for pure methanol and the binary structures are statistically similar.