Abstract
Hierarchical titanium silicalite-1 (HTS-1) zeolites are an important class of catalytic materials due to their enhanced mass transfer and improved catalytic performance. In this study, HTS-1 zeolites have been successfully prepared by the hydrothermal crystallization of carbon-silica-titania (CST) composites. Compared with the direct carbonization method, the mild carbonization of SiO2-TiO2/Tween 40 xerogel in the presence of sulfuric acid can effectively improve both the content and mesoporous structure of carbon material in the CST composites, which enables carbon materials to better play the role of a mesoporous template during the crystallization process. The resultant zeolite has both ordered micropores and interconnected mesopores and macropores, which are similar to the skeleton of the carbon template trapped in the TS–1 crystals. Moreover, the HTS–1 zeolite displays outstanding catalytic performance in oxidative desulfurization of bulky sulfur compounds.
Highlights
In recent decades, Titanium silicalite-1 (TS-1) has attracted much attention due to its interesting catalytic performances in selective oxidation reactions, such as hydroxylation of aromatics, epoxidation of olefins, and especially the oxidation of S-containing organic compounds [1,2]
Its intrinsic microspores hinder the diffusion of bulky organic sulfide molecules to active sites, which restricts its further applications in the oxidative desulfurization process [2]
The ST/Tween 40 (T-40) xerogel is proven to have a mesostructure by small-angle XRD, and its mesostructure changes little upon sulfuric acid pre-treatment (Figure S1a)
Summary
Titanium silicalite-1 (TS-1) has attracted much attention due to its interesting catalytic performances in selective oxidation reactions, such as hydroxylation of aromatics, epoxidation of olefins, and especially the oxidation of S-containing organic compounds [1,2]. Its intrinsic microspores hinder the diffusion of bulky organic sulfide molecules to active sites, which restricts its further applications in the oxidative desulfurization process [2] To overcome this drawback, intensive research on the preparation of TS-1 zeolites with hierarchical pores have been carried out [3,4,5,6,7,8,9,10]. Soft templates are generally easy to disperse throughout the synthesis system, whereas hard templates are difficult to disperse in the synthesis system due to the weak interaction between templates and inorganic precursors To solve this problem, polyvinyl alcohol, which possesses rich –OH groups, has been used as a linking agent to connect multi-wall carbon nanotubes and TS-1. Catalytic properties of the resulting samples in the oxidative desulfurization of bulky sulfur compounds are studied
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