Reutilization of silicon,  · 1. Introduction A number of porous materials based on silica and alumina are available industrially and largely applied by the chemical industry as heterogeneous catalysts, supports or components of heterogeneous catalysts (Busca, 2014a), as well as adsorbents for fluid mixtures purifications or separations (), as well as ion exchangers in the detergency field (Zeodet, 2019).