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Grafting of Alumina on SBA-15: Effect of Surface Roughness

2008; American Chemical Society; Volume: 24; Issue: 17 Linguagem: Inglês

10.1021/la801547u

1520-5827

Arnošt Zukal, Helena Šiklová, Jiřı́ Čejka,

Aerogels and thermal insulation

Alumina-grafted materials were prepared by postsynthesis alumination of mesoporous SBA-15 silica in an aqueous solution of aluminum chlorhydrol. Prepared samples were characterized by nitrogen adsorption, scanning electron microscopy, X-ray powder diffraction, and (27)Al magic-angle-spinning NMR. The successive grafting of alumina on SBA-15 leads to a gradual filling of the corona surrounding the mesopores. As a consequence smoothing of the mesopore surface takes place. The in-depth analysis of nitrogen adsorption data proves that the alpha s method affords real values of the structure parameters, while the Kruk, Jaroniec, and Sayari (KJS) procedure based on the BJH algorithm provides only effective data corresponding to cylindrical mesopores of smooth geometrical surface. The quantification of the roughness of the SBA-15 mesopore surface based on the comparison of data obtained from the alpha s plot and KJS method was carried out.