利用X射线粉末衍射、氢程序升温还原、X射线光电子能谱和透射电镜技术研究了在低Ni含量和低比表面积六铝酸盐催化剂LaNiAl_(11)O_(19-δ)上CH_4-CO_2重整反应的积炭行为,考察了该催化剂表面积炭的形貌、来源、积炭物种及其反应性能.结果表明,LaNiAl_(11)O_(19-δ)催化剂表面积炭主要由甲烷裂解产生,并以Ni的碳化物形式存在于活性中心Ni的周围.根据积炭物种活化程度的难易可分为C_α,C_β和C_γ三种类型,其中C_α为容易被CO_2消除的化合碳,而C_β和C_γ则是不易被CO_2消除的石墨碳.透射电镜结果表明,C_α以碳纳米管形式分布于催化剂颗粒周围,但金属Ni活性中心仍能暴露于气相中,因而不影响催化剂的活性.
Carbonaceous deposits formed during the reaction of CO_2 reforming of methane over hexaaluminate LaNiAl_(11)O_(19-δ) catalyst andtheir reactivity were studied by X-ray diffraction, He-temperature-programmed reduction, X-ray photoelectron spectroscopy, and transmission electron microscopy. The deposited carbon was mainly originated from CH_4 decomposition, and it could be classified as three kinds of surface carbon species, I.e. C_α, C_β, and C_γ species on LaNiAl_(11)O_(19-δ).The carbide carbon, C_α, was very active and could be eliminated by CO_2 easily. However, both C_βand C_γ were the graphitic carbon and were difficult to be eliminated by CO_2. It was suggested that C_α was a kind of nanotube-like carbon, which did not affect the catalytic activity of hexaaluminate LaNiAl_(11)O_(19-δ)catalyst.
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