Abstract
TS-1 zeolite has outstanding performance in the catalytic reactions with hydrogen peroxide as catalytic promoter. However, the narrow pore size (< 1.0 nm) of traditional TS-1 makes it difficult for bulky organic compounds to contact with the active sites in the pores, which seriously limits application of TS-1. Recently, the introduction of mesoporous structure into microporous TS-1 becomes a hot research topic. Meanwhile, the huge synthesis cost of TS-1 is another main reason hindering its industrial application. In this paper, mesoporous TS-1 was successfully synthesized using sodium silicate as silicon source and titanium trichloride as titanium source under the template conditions of tetrapropylammonium hydroxide (TPAOH) and cationic polymer. The mesoporous TS-1 was characterized by X-ray diffraction (XRD), N2 adsorption, scanning electric microscopy (SEM), transmitting electric microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR) and UV-Vis Spectrum spectra (UV-Vis). Results show that the synthesized TS-1 zeolites have good crystallinity and tetra-coordinated framework Ti atoms, and there are abundant mesoporous structures in the zeolite crystals. The results of oxidation experiments show that conversion of diphenyl sulfide and dibenzyl sulfide with mesoporous TS-1 are 97.3 % and 85.3 % respectively, while that conversion with microporous TS-1 are 75.7 % and 63.5 respectively.
Highlights
As one titanium silicalite zeolite, TS-1 has attracted wide attention due to its excellent catalytic performance in selective oxidation and epoxidation with hydrogen peroxide as oxidant[1]
The mesoporous TS-1 was characterized by X-ray diffraction (XRD), N2 adsorption, scanning electric microscopy (SEM), transmitting electric microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR) and UV-Vis Spectrum spectra (UV-Vis)
The small pore size of traditional TS-1 limits its application in bulky molecule catalytic conversion, and the high cost greatly restricts its application in industrial production
Summary
As one titanium silicalite zeolite, TS-1 has attracted wide attention due to its excellent catalytic performance in selective oxidation and epoxidation with hydrogen peroxide as oxidant[1]. Choi[3] synthesized porous titanium silicalite catalytic materials by using expensive multi head quaternary ammonium salt surfactant as soft template method. Expensive organosilicon sources (TEOS) and a large number of organic titanium sources (tetrabutyl titanate, TBOT) were used in the synthesis system, and a large number of small molecular template, such as tetrapropyl ammonium hydroxide (TPAOH) were used. All these items cause the high cost of TS-1 zeolite. It has been reported that microporous TS-1 zeolite can be synthesized by using cheap inorganic silicon sources (such as silica sol) and titanium sources (such as titanium trichloride and titanium sulfate) in the presence of TPAOH [4,5]. The synthesis of mesoporous TS-1 using inorganic silicon and titanium sources has always been an unsolved problem
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