연구홍보포털

논문 초록 (Abstract)

Hierarchical zeolites alleviate intracrystalline transport limitations, but their kinetic advantage is often assessed at a single reactant loading. Here, Friedel–Crafts alkylation of benzene with benzyl alcohol was used as a model reaction to compare nanosponge and conventional bulk Beta zeolites over benzyl alcohol loadings of 2.4–28.8 mmol. Turnover number (TON), turnover frequency (TOF), apparent pseudo-first-order rate coefficients (kapp), and temperature-dependent apparent activation energies were evaluated. At 2.4 mmol, the two catalysts showed nearly identical kapp values (~95 × 10-4 min-1), whereas increasing benzyl alcohol loading caused much stronger rate suppression over bulk Beta. At 28.8 mmol, kapp was 12.3 × 10-4 min-1 for nanosponge Beta and 4.87 × 10-4 min-1 for bulk Beta, giving a 2.53-fold difference. Nanosponge Beta also exhibited substantially higher TON at high loading, while the TOF difference was more modest, indicating that hierarchical porosity primarily sustains effective acid-site utilization and mitigates loading-induced deactivation rather than strongly increasing initial site-normalized activity. Arrhenius analysis gave apparent activation energies of 53.05 and 46.62 kJ mol-1 for nanosponge and bulk Beta, respectively, arguing against a lower activation barrier as the origin of the enhanced performance. Molecular dynamics simulations qualitatively supported this interpretation by showing faster penetration of benzene and benzyl alcohol into thinner zeolite slabs. These results demonstrate that reactant-loading-dependent kinetic analysis can quantitatively reveal the transport advantage of hierarchical zeolites under diffusion-sensitive conditions. Such high-loading tolerance is particularly relevant to process-intensified alkylation, where operation at higher substrate concentrations may improve reactor productivity while potentially reducing dilution- and recycle-related burdens.