The behavior of the surface Si/(Si+Al) ratio in the FCC catalyst deactivation

• Published in: Journal of electron spectroscopy and related phenomena 2020-02, Vol.239, p.146932, Article 146932
• Main Authors: Amaya, Álvaro A., González, Carlos A., Martínez O., Fernando
• Format: Article
• Language: English
• Subjects: FCC catalyst; Surface Si/(Si+Al) ratio; X-ray photoelectron spectroscopy
• ISSN: 0368-2048; 1873-2526
• DOI: 10.1016/j.elspec.2019.146932

•Surface: Si/(Si+Al) ratio depends on the deactivation of the catalyst.•Surface Si/(Si+Al) ratio increases when the FCC catalyst is deactivated.•Excess Al2O3 is probably removed from the surface of the catalyst. Herein, the surface Si/(Si+Al) ratio of a series of FCC catalysts was studied by X-ray Photoelectron Spectroscopy (XPS). Firstly, some of the interferences of the XPS signals from Si, and Al elements were studied and fixed by using the Multiple Linear Regression method (MLR). Subsequently, the Si/(Si+Al) ratio of a set of FCC catalysts was analyzed and this information was correlated with the surface area analysis (BET method). This work showed that the surface Si/(Si+Al) ratio of low deactivated FCC catalyst was lower than its bulk Si/(Si+Al) ratio, suggesting that there is a high content of Al2O3 on the surface of the catalyst when it is slightly deactivated. The surface Si/(Si+Al) ratio of the FCC catalyst increased as the surface area decreased (total and microporous) due to the deactivation of the catalyst; it means that the surface Si/(Si+Al) ratio is strongly affected by the deactivation of the catalyst. The surface Si/(Si+Al) ratio of the equilibrium FCC catalyst samples (Ecat) were very similar to their bulk Si/(Si+Al) ratio. This fact suggests that the surface Si/(Si+Al) ratio of an FCC catalyst progressively increases up to reach the bulk Si/(Si+Al) ratio, therefore the surface Si/(Si+Al) ratio is related to the FCC catalyst deactivation phenomenon.