Abstract
The nonoxidative catalytic dehydrogenation of ethane allows the production of ethylene at lower temperatures than those applied in steam crackers. This, however, requires stable catalysts that minimize coke production. Here, we report a single-component, promoter-free, low-loading, Cr-based catalyst exhibiting high activity, long-term stability, and improved regeneration properties for the direct dehydrogenation of ethane to ethylene. According to our detailed operando X-ray absorption spectroscopic analysis, the use of all-silica MFI zeolite as support promotes the stabilization of CrII(−O–Si≡)2 species with high coke resistance, even when the dehydrogenation is carried out under high ethane partial pressures (1.5 bar).
Highlights
Ethylene is one of the most important building blocks for the petrochemical industry.[1]
TEM images (Figures 1a and S15a) indicate that the Cr species are well-dispersed with no appreciable formation of nanoparticles at 0.8 wt % Cr loading, while some nanoparticles are observed for the sample with 3.0 wt % Cr loading
The range of peak temperatures (380−420 °C) on the temperature-programmed reduction (TPR) profiles (Figure S2) of 0.8Cr/MFI and 3.0Cr/MFI catalysts can be assigned to the reduction of Cr6+ to Cr2+, which was confirmed by the operando X-ray absorption near edge structure (XANES) study (Figures 2a,b)
Summary
Ethylene is one of the most important building blocks for the petrochemical industry.[1]. BET analysis of the 0.8Cr/MFI catalyst after second catalytic runs (without calcination) shows a slight decrease in micropore area and volume (Table S1), suggesting that the pore structure is preserved very well, which is one of the main reasons for its excellent regeneration ability.
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