Heterogeneous catalysts obtained by wet impregnation of ruthenium or palladium onto mesoporous silica of SBA-16 type
Paulina Szczyglewska, Agnieszka Feliczak-Guzik and Izabela Nowak
Faculty of Chemistry, Adam Mickiewicz University in Poznań, Umultowska 89b, 61-614, Poznań, POL
Mesoporous silicas of SBA-16 (Santa Barbara Amorphous-16) type are high surface area materials that possess a well-developed and highly ordered system of mesopores[D. Carta, et. all, J. Non.-Cryst. Solids, (2014), 401, 134-138][A. Feliczak-Guzik, et. all, Micropor. Mesopor. Mat., (2016), 220, 231-238]. Transition metal atoms can modify surface of these materials among others. The mesoporous morphology plays an important role in the application on separation and catalytic properties therefore, the synthesis and characterization of ordered mesoporous silicas is a very important aspect nowadays1. The main purpose of the study was to obtain SBA-16 materials containing ruthenium or palladium atoms into the structure (1 wt.%) in external positions. Synthesis of siliceous materials of SBA-16 type was performed via typical hydrothermal method, using standard chemicals and procedures. Tetraethyl orthosilicate (TEOS) and nonionic triblock copolymer Pluronic F127 (EO106PO70EO106) were used as a silica source and structure-directing agent, respectively. Ruthenium or palladium atoms were introduced onto the surface of the silica by wet impregnation by using RuCl3*H2O or PdCl2 and followed by hydrogen reduction in order to obtain pure metallic species. These materials were characterized by various techniques, including X-ray diffraction (XRD), low temperature nitrogen gas sorption, Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). XRD patterns were typical for SBA-16 mesoporous structure. According to the IUPAC recommendations, nitrogen adsorption-desorption isotherms obtained for both materials may be ascribed to type IV(a). Additionally N2 sorption analysis revealed that synthesized materials possess well-developed surface area and narrow pore size distribution. FTIR analysis confirmed the presence of bands typical for silica materials. TEM and SEM images gave information about the structure of the support and the dispersion of the metals.
National Science Centre is kindly acknowledged for the financial support (project no: DEC-2013/10/M/ST5/00652).
Z. Cao, et. all, Chem. Eng. Sci., (2016), 155, 141-152↩