@article{TEXTUAL,
      recid = {9695},
      author = {Hack, John H. and Ma, Xinyou and Chen, Yaxin and  Dombrowski, James P. and Lewis, Nicholas H. C. and Li,  Chenghan and Kung, Harold H. and Voth, Gregory A. and  Tokmakoff, Andrei},
      title = {Proton Dissociation and Delocalization under Stepwise  Hydration of Zeolite HZSM-5},
      journal = {The Journal of Physical Chemistry C},
      address = {2023-08-08},
      number = {TEXTUAL},
      abstract = {The protonation behavior of zeolite Brønsted acid sites  (BAS) in the presence of water is important for the  performance of these widely used catalysts. Despite  extensive study, the number of water molecules necessary  for deprotonation is not well understood, in large part  because experiments have been unable to access this  information. In this work, we report experimental evidence  for full deprotonation of the BAS in the presence of two or  more water molecules, with a deprotonation energy of 1.6  kcal/mol. Linear IR absorption and 2D IR spectra were  measured over a wide range of controlled hydration levels  from 0.5 to 8.0 equivalents of H<sub>2</sub>O/Al at a  constant temperature. Distinct spectral signatures of the  protonated BAS and excess proton are identified, and their  hydration dependence is analyzed quantitatively. Using the  experiment as a benchmark, ab initio molecular dynamics  simulations are reported that reproduce the experimental  trends in the protonation state and IR spectra. The proton  charge position and delocalization are quantified in  clusters of 1–8 H<sub>2</sub>O molecules using the recently  developed rCEC method. This analysis provides insight into  the proton structure in confined water clusters, showing  that the excess charge remains relatively localized between  two oxygen atoms across the hydration range.},
      url = {http://knowledge.uchicago.edu/record/9695},
}