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Characterization and catalytic behavior of hydrotalcite-derived Ni–Al catalysts for methane decomposition
International Journal of Hydrogen Energy ( IF 7.2 ) Pub Date : 2020-05-29 , DOI: 10.1016/j.ijhydene.2020.04.141
Zemin Shi , Chunsheng Wan , Min Huang , Jinhua Pan , Ruizhi Luo , Dalin Li , Lilong Jiang

A series of Ni catalysts were prepared from Ni–Al hydrotalcite-like compounds (HTlcs) by varying the Ni/Al molar ratio (1–4) and calcination temperature (773–1173 K) of HTlcs. The catalysts were reduced with H2 at 1073 K and tested for CH4 decomposition at 773–923 K on a thermal gravimeter. Various techniques including N2 physical adsorption, XRD, H2-TPR, XPS, HAADF-STEM, TEM, and Raman were applied to characterize the catalysts and the as-produced carbon. The characterizations show that calcination of Ni–Al HTlcs leads to Ni(Al)O solid solution and minor NiO and/or NiAl2O4 spinel may be formed depending on the Ni/Al ratio and calcination temperature; upon reduction at 1073 K, most nickel species are reduced to metallic Ni. In CH4 decomposition, carbon yield shows a volcano-type dependence on the Ni content with the optimum Ni/Al ratio equal to 3. On the other hand, carbon yield is affected by the calcination temperature of the Ni3Al HTlcs to a small extent. Carbon yield is also significantly affected by the reaction temperature, which decreases remarkably with a rise of temperature to 923 K. TEM and Raman indicate that fish-bone carbon nanofibers are formed at 773–823 K, whereas multi-walled carbon nanotubes are formed at 873–923 K.



中文翻译:

水滑石衍生的Ni-Al催化剂的甲烷分解特性和催化行为

通过改变Ni / Al摩尔比(1-4)和煅烧温度(773-1173 K),由Ni-Al类水滑石化合物(HTlcs)制备了一系列Ni催化剂。在1073 K下用H 2还原催化剂,并在热重力仪上测试在773–923 K下进行CH 4分解。应用了各种技术,包括N 2物理吸附,XRD,H 2 -TPR,XPS,HAADF-STEM,TEM和拉曼,以表征催化剂和所产生的碳。表征表明,Ni-Al HTlcs的煅烧导致Ni(Al)O固溶体和少量的NiO和/或NiAl 2 O 4取决于Ni / Al比和煅烧温度,可以形成尖晶石。在1073 K下还原时,大多数镍物种都还原为金属Ni。在CH 4分解中,最佳Ni / Al比等于3时,碳产率显示出对Ni含量的火山式依赖性。另一方面,碳产率受Ni 3 Al HTlcs的煅烧温度影响很小。程度。碳收率还受到反应温度的显着影响,温度随温度升高至923 K而显着降低。TEM和Raman表明,鱼骨碳纳米纤维的形成温度为773-823 K,而多壁碳纳米管的形成温度为773-823K。 873–923千。

更新日期:2020-06-30
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