关键词：
Methane dehydroaromatization
Mo/HZSM-5
BTX
Physical mixing
NiO
Silica shell
Carbon nanotube
摘要：
In our previous study,the activity and stability of the Mo/HZSM-5 catalyst were enhanced by mixing physically with NiO in methane dehydroaromatization(MDA)*** has been confirmed that the physically mixed NiO not only promoted the dispersion of MoC_(x)active sites but also reduced the coke formation on the MoC_(x)owing to the CNTs growth on ***,the promotional effect of NiO was limited when the particle size was reduced,due to the excessive interaction with MoOx(forming NiMoO_(4))which is detrimental to the MoC_(x)*** this study,to overcome the limitation,silica shell on NiO particles with various sizes(5,15,110 nm)was *** catalyst with silica shell coated NiO with the size of 15 nm exhibited a significant improvement in both BTX yield and stability,and the catalyst with silica shell coated NiO with the size of 5 nm achieved the highest maximum BTX yield,about 7.2%.This study demonstrates that the catalytic performance improved as the NiO particle size decreased with the introduction of the silica *** transmission electron microscopy-energy dispersive spectroscopy,X-ray diffraction,temperature-programmed surface reaction of methane,CO chemisorption,visible Raman,and thermogravimetric analysis allowed us to confirm that a thin silica shell further enhances the MoC_(x)dispersion while preventing the formation of Ni-Mo ***,when the size of NiO decreased to 5 nm,CNT growth on Ni was limited during the reaction,which is crucial for reducing coke formation on Mo active sites,thereby resulting in the decreased catalyst stabilization ability of ***,this study indicates that the introduction of a silica shell in a controlled way can significantly enhance the promotional effect of physically mixed NiO on MDA.
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