A new route for the synthesis of titanium silicalite-1

A new and efficient route using inexpensive reagents such as fumed silica and tetrapropylammonium bromide is proposed for the synthesis of titanium silicalite-1. High crystalline titanium silicalite-1 was obtained in alkaline medium, using sodium hydroxide as HO− ion source required for the crystallization process. Hydrolysis of titanium source with formation of insoluble oxide species was prevented by titanium complexation with before structuring gel. The final solids were fully characterized by powder X-ray diffraction, scanning electron microscopy, Fourier transform infrared, ultraviolet-visible diffuse reflectance, Raman and atomic absorption spectroscopies, as well as nitrogen sorption analysis. It was found that a molar ratio Ti:Si of about 0.04 in the initial reaction mixture is the upper limit to which well formed titanium silicalite-1 with channels free of crystalline or amorphous material can be obtained. Above this value, solids with MFI type structure containing both Ti isomorphously substituted in the network and extralattice anatase nanoparticles inside of channels is formed.

Graphical abstractWell-prepared TS-1 was synthesized by an innovative procedure using inexpensive reagents such as fumed silica and TPABr as structure-directing agent. This is the first time when highly crystalline TS-1 is obtained in basic medium, using sodium hydroxide as HO− ion source required for the crystallization process. Hydrolysis of titanium source has been prevented by titanium complexation with acetylacetone before structuring gel.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► TS-1 was obtained using cheap reagents as fumed silica and tetrapropylammonium bromide. ► First time NaOH was used as source of OH− ions required for crystallization process. ► The hydrolysis Ti alkoxides was controlled by Ti complexation with 2,4-pentanedione.