| Abstract
| - Post-steam-treatment is a facile and effective method for improving the catalytic performances of Mo/HZSM-5catalysts in methane dehydroaromatization under nonoxidative conditions. The treatment can enhance thestability of the catalyst and also give a higher methane conversion and a higher yield of light aromatics, aswell as a decrease in the formation rate of carbonaceous deposits. 27Al, 29Si, and 1H multinuclear magic anglespinning nuclear magnetic resonance, X-ray photoelectron spectroscopy, X-ray diffraction, X-ray fluorescencespectroscopy, and thermogravimetric analysis measurements as well as catalytic reaction evaluations wereemployed to conduct comparative studies on the properties of the catalysts before and after the post-steam-treatment. The results revealed that the number of free Brönsted acid sites per unit cell decreased, while moreMo species migrated into the HZSM-5 channels for the 6Mo/HZSM-5 catalysts after the post-steam-treatment.In addition, the average pore diameter was also larger for the post-steam-treated catalysts, and this wasadvantageous for mass transport of the reaction products. However, a severe post-steam-treatment, i.e., withlonger treating time, of the 6Mo/HZSM-5 catalyst will lead to the formation of the Al2(MoO4)3 phases, whichis detrimental to the reaction.
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