A first-principles evaluation of the stability, accessibility, and strength of Brønsted acid sites in zeolites

摘要: Abstract Catalytic reactions of zeolites occur mainly at their acid sites; however, there is a lack comprehensive method to characterize the sites by multiple aspects due complexity associated with both host structures and origins formation. Here we propose computational approach, from thermodynamic kinetic points view, evaluate jointly energetic stability , space accessibility strength (SAS) critical catalytic performance in zeolites. In this work, evaluated SAS systematically for various potential Bronsted zeolites, using density functional methods surface area calculations. The total energy was used compare relative stabilities same type. deprotonation (DPE) calculated represent strength. Moreover, proposed concept local accessible (LASA) measure localized region molecular complex shape. were comprehensively including bridging hydroxyl (BH), nest (NH), terminal silanol (TS) internal pores on external surfaces MFI-type zeolite. We found most stable are Al2/H2, Al9/H2, Al1/H1 sites, respectively, intra-crystalline BH, BHs (0 1 0) (1 0 0) surfaces. NH located T4, T7, T5 defective pores, an site depends OH orientation studied sites. Most difficult access connected hydrogen bonds. decreases as BH > NH > TS. Both pore geometry bonds can enhance first-principles computation provides approach that facilitates evaluation design zeolite catalysts.