In-situ regeneration mechanisms of hybrid catalysts in the one-step synthesis of dimethyl ether from syngas
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One-step synthesis of dimethyl ether (DME) from H2/CO has been studied in a fixed bed reactor over hybrid catalyst CuOZnOAl2O3/γ-Al2O3-HZSM-5. The physicochemical properties of fresh and used catalysts were also studied by means of H2-TPR, XRD and N2O chemisorptions. The results showed that for deactivated catalysts by sintering, redox cycle was an effective method for in-situ regeneration. There were two different regeneration mechanisms according to various atmospheres: (i) For O2-syngas cycle, sintered Cu particles were re-dispersed and initial activity was restored mostly. The process was reversible, which was called reversible regeneration; (ii) for N2O (CO2)-syngas cycle, Cu particles could not be re-dispersed and catalytic activity was restored a little due to the regulation of surface state. On the other hand, this process could depress the deactivation velocity and was irreversible, which was called irreversible regeneration.
Keywordsdimethyl ether sintering deactivation regeneration reversible regeneration irreversible regeneration
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