Y zeolite molecular sieves

Recently, Professor Li Yadong of Tsinghua University and Professor Chen Jiesheng (co-corresponding author) of Shanghai Jiaotong University have jointly reported a new type of molecular sieve (M-ISAS@Y, M = Pt, Pd, Ru, Rh, Co, General strategy for preparing metal single-atom site (M-ISAS) catalysts in Ni, Cu). First, the author separated the metal-ethylenediamine (M-EDA) complex in situ during the crystallization process of the molecular sieve and confined it in the β cage of the Y-type molecular sieve, and then fixed the metal atoms in the molecular sieve by thermal reduction. Compared with the traditional IWI method, this in-situ synthesis strategy ensures that the precursor is uniformly dispersed in the molecular sieve bulk phase. More importantly, M-EDA is monodisperse in each β cage, effectively preventing agglomeration and improving the stability of single-atom sites. The authors used aberration-corrected scanning transmission electron microscopy, extended X-ray absorption fine structure (EXAFS), and density functional theory calculations to determine that oxygen on the six-membered ring plane skeleton can anchor platinum single atoms. The reaction substrate can freely access these single-atom sites through β-cage and supercage. Using ethane dehydrogenation as the probe reaction, the single-atom catalyst showed excellent catalytic activity. Furthermore, the author used Pt-ISAS@HY in the isomerization reaction of n-hexane, combined with the catalytic dehydrogenation/hydrogenation on Pt-ISAS and the catalytic olefin isomerization on HY molecular sieve, the overall catalytic efficiency of the catalyst is better than the reported Pt -Molecular sieve catalyst. The research results were published in the famous journal J. Am. Chem. Soc. with the title "A General Strategy for Fabricating Isolated Single Metal Atomic Site Catalysts in Y Zeolite".