Promotional effect of silica shell coated NiO physically mixed with Mo/HZSM-5 catalyst on methane dehydroaromatization  

二氧化硅壳层包覆NiO与Mo/HZSM-5物理混合对甲烷脱氢芳构化的促进作用

作　　者：Jangeon Roh Kihun Nam Yong Hyun Lim Yeseul Hwang Hae Won Ryu Kyoungmin Kim Gyeongmin Seok Yangho Jeong Jong Hun Kang Jungyeop Lee Jong-Ki Jeon Do Heui Kim Jangeon Roh;Kihun Nam;Yong Hyun Lim;Yeseul Hwang;Hae Won Ryu;Kyoungmin Kim;Gyeongmin Seok;Yangho Jeong;Jong Hun Kang;Jungyeop Lee;Jong-Ki Jeon;Do Heui Kim(首尔国立大学化学工艺研究所,化学与生物工程学院,韩国首尔08826;公州国立大学化学工程系,韩国天安31080)

机构地区：[1]School of Chemical and Biological Engineering,Institute of Chemical Processes,Seoul National University,1 Gwanak-ro,Gwanak-Gu,Seoul 08826,Republic of Korea [2]Department of Chemical Engineering,Kongju National University,Cheonan 31080,Republic of Korea

出　　处：《Chinese Journal of Catalysis》2025年第4期220-233,共14页催化学报(英文)

基　　金：韩国科学、信息通信技术与未来规划部(2021M3D3A1A01022109);碳中和工业战略技术发展计划(RS-2023-00261088).

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)reaction.It 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 Ni.However,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)dispersion.In this study,to overcome the limitation,silica shell on NiO particles with various sizes(5,15,110 nm)was introduced.The 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 shell.Combined 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 complexes.However,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 Ni.Overall,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.甲烷脱氢芳构化(MDA)反应可将甲烷直接转化为苯、甲苯和二甲苯,在天然气转化领域具有显著应用潜力。前期研究表明Mo/HZSM-5与NiO通过物理混合提高了其催化MDA反应的活性和稳定性.物理混合的NiO不仅促进了MoC_(x)活性位点的分散,而且由于Ni诱导碳纳米管(CNT)生长,还减少了MoC_(x)上积碳的形成.然而,当NiO粒径减小时,其与MoO_(x)间过强的相互作用会形成NiMoO_(4),不利于MoC_(x)的分散,限制促进效果.因此,本文通过在NiO颗粒表面包覆不同尺寸(5、15和110 nm)的二氧化硅壳层以解决该问题.实验表明,当二氧化硅壳层粒径为15 nm时,包覆的NiO催化剂上苯、甲苯和二甲苯收率和稳定性方面均显著提高;当粒径为5 nm时,其包裹的NiO催化剂上二甲苯收率最高,约为7.2%.结果表明,随着二氧化硅壳层的引入,NiO粒径减小,催化性能得到改善.结合透射电镜-能量散射谱、X-射线衍射、CH_(4)-程序升温表面反应、CO化学吸附、可见拉曼光谱和热重分析结果表明,薄的二氧化硅壳层促进了MoC_(x)的分散,同时抑制了Ni-Mo复合氧化物的形成.然而,当NiO的尺寸减小到5 nm时,反应过程中CNT在Ni上的生长受到抑制,这对于减少Mo活性位点上的积碳形成至关重要,因此使得Ni催化剂稳定性下降.本研究以可控的方式引入二氧化硅壳层可以显著增强物理混合的NiO对MDA反应的促进作用.

关 键 词：Methane dehydroaromatization MO/HZSM-5 BTX Physical mixing NIO Silica shell Carbon nanotube 

分 类 号：O643.36[理学—物理化学]