Distribution of Aluminum Species in Zeolite Catalysts: ²⁷Al NMR of Framework, Partially-Coordinated Framework, and Non-Framework Moieties.

ABSTRACT: The structure of aluminum-containing moieties in and within zeolite H-ZSM-5 catalysts is a complex function of the elemental composition of the catalyst, synthesis conditions, exposure to moisture, and thermal history. ²⁷Al NMR data collected at field strengths ranging from 7.05 to 35.2 T, i.e., ¹H Larmor frequencies from 300 to 1500 MHz, reveal that Al primarily exists as framework or partially coordinated framework species in commercially available dehydrated H-ZSM-5 catalysts with Si/Al ranging from 11.5 to 40. Quantitative direct-excitation and sensitivity-enhanced ²⁷Al NMR techniques applied over the wide range of magnetic field strengths used in this study show that prior to significant hydrothermal exposure, detectable amounts of nonframework Al spec

SUBMITTER: Chen K 

PROVIDER: S-EPMC8212420 | biostudies-literature | 2021 May

REPOSITORIES: biostudies-literature