Origin and Structural Characteristics of Tri-coordinated Extra-framework Aluminum Species in Dealuminated Zeolites
Citations Over TimeTop 10% of 2018 papers
Abstract
Post-synthetic dealumination treatment is a common tactic adopted to improve the catalytic performance of industrialized zeolitic catalysts through enhancements in acidity and stability. However, among the possible extra-framework aluminum (EFAL) species in dealuminated zeolites such as Al3+, Al(OH)2+, Al(OH)2+, AlO+, AlOOH, and Al(OH)3, the presence of tri-coordinated EFAL-Al3+ species, which exhibit large quadrupolar effect due to the lack of hydrogen-bonding species, was normally undetectable by conventional one- and two-dimensional 1H and/or 27Al solid-state nuclear magnetic resonance (SSNMR) techniques. By combining density functional theory (DFT) calculations with experimental 31P SSNMR using trimethylphosphine (TMP) as the probe molecule, we report herein a comprehensive study to certify the origin, fine structure, and possible location of tri-coordinated EFAL-Al3+ species in dealuminated HY zeolite. The spatial proximities and synergies between the Brønsted and various Lewis acid sites were clearly identified, and the origin for the observed EFAL-Al3+ species with ultra-strong Lewis acidity was deduced to be at the expense of adjacent Brønsted acid sites. The excellent performance of such tri-coordinated EFAL species was furthermore confirmed by glucose isomerization reactions.
Related Papers
- → Promoting a non-heme manganese complex catalyzed oxygen transfer reaction by both lewis acid and Brønsted acid: Similarities and distinctions(2017)15 cited
- → Brönsted and Lewis acid catalysis of XY–ZH cycloadditions(1982)35 cited
- → Structure and surface properties of ZrO2-supported WO3 nanostructures(2000)7 cited
- Study on Surface Acidity of Solid-acid Catalysts(2000)
- → Adducts with Brönsted acids(1963)