Propane Aromatization on Zn-Modified Zeolite BEA Studied by Solid-State NMR in Situ

Abstract

The conversion of propane (propane-1-13 C and propane-2-13 C) on Zn/H-BEA zeolite at 520-620 K has been studied by 1 H and 13 C (CP) MAS NMR. Propene adsorption complex with zinc sites (π-complex) and σ-allylzinc species as intermediates have been identified in the course of propane conversion to aromatics. The mechanism leading to the formation of methane and ethane, which are constituents of an undesirable route in propane conversion, has been examined by kinetic modeling of the expected reaction network based on in situ 1 H MAS NMR kinetic measurements of the reaction performance. The pathways for propane aromatization and hydrogenolysis have been proposed. Hydrogenolysis of propane has been concluded to occur with the involvement of both Brønsted acid sites and Zn sites.

New insights into hierarchical metal-containing zeolites; synthesis and kinetic modelling of mesoporous gallium-containing ZSM-5 for propane aromatization

“…The estimated value for the apparent activation energy of dehydrogenation over microporous Ga0.35HZ80 (70 kJmol -1 ) is in good agreement with that of Gabrienko et al [40] who reported an apparent activation energy of 80 kJmol -1 using Zn-modified zeolite BEA as catalyst for propane aromatization. Narbeshuber et al [39] reported Figures 1-2), then, the improved propane aromatization performance over mesoporous HZ80 can be related to the presence of mesopores.…”

Recent development in in situ NMR study on heterogeneous catalysis: mechanisms of light alkane functionalisation

“…133 and 19.8 ppm, contributed from methyl substituted aromatics, appear at 573 K and their intensities grow with temperature. Similar observations are also The similar results were also obtained from the system containing propane (1-13 C-propane and 2-13 C-propane) on Zn/H-BEA zeolite at 520-620 K. Stepanov et al 80 claimed that the transformation of propane occurs by two competitive pathways, aromatisation and hydrogenolysis. Adsorbed propene complexes with zinc sites (p-complex) and s-allylzinc species are successive intermediates toward aromatics, evolved probably from n-propylzinc species formed at the dissociative adsorption of propane on ZnO species.…”

Effects of Zinc and Magnesium Addition to ZSM-5 on the Catalytic Performances in 1-hexene Aromatization Reaction

“…Dual roles of Zn as dehydrogenation and aromatization were revealed and put forward. Usually, light paraffin was applied as feed gas [3,6,30]. In the case of olefin as feed, the situation is a little different.…”

“…Up to now, much of the research about aromatization reaction focused on ZSM-5, Beta, and Y zeolite based catalysts due to their special channel structure and intrinsic acidity [5,6]. Meanwhile, ZSM-5 modified by Zn [3,[7][8][9], Ga [10][11][12] and Pt [13] have attracted more attention.…”