TS‐1@MCM‐48 Core‐Shell Catalysts for Efficient Oxidation of p‐Diethylbenzene to High Value‐Added Derivatives

Abstract

To expand the market capacity of p‐diethylbenzene (PDEB), core‐shell zeolite (TS‐1@MCM‐48) is designed as a catalyst for PDEB oxidation. TS‐1@MCM‐48 catalyst is synthesized by in‐situ crystallization method and characterized by X‐ray diffraction (XRD), transmission electron microscope (TEM), scanning electron microscope (SEM), X‐ray photoelectron spectroscopy (XPS), N2 adsorption‐desorption, in‐situ electron paramagnetic resonance (EPR) and 29Si nuclear magnetic resonance (29Si MAS‐NMR). Oxidation of PDEB by H2O2 was investigated systematically in liquid phase. The conversion of PDEB over TS‐1@MCM‐48 was 28.1% and the total selectivity was 72.6%, where the selectivity of EAP (p‐ethylacetophenone) and EPEA (4‐ethyl‐α‐methylbenzyl alcohol) was 28.6% and 44.0%, respectively. Compared with TS‐1 and MCM‐48 zeolite, the conversion rate of reactants and the selectivity of products have been significantly improved. The catalytic performance of TS‐1@MCM‐48 is derived from its well‐crystallized microporous core and mesoporous shell with regular channels, which make active sites of TS‐1 zeolite in the catalyst be fully utilized and mass transfer resistance be largely reduced. Further through theoretical calculation, we propose that the oxidation of PDEB is the result of the combination and mutual transformation of free radical process and carbocation process. Core‐shell structure ensures the conversion rate of raw materials and improves the selectivity of products.

Catalytic oxidative desulfurization performance of a modified nano-sized β zeolite loaded with different structural polyoxometalates

“…Hydroxyl radicals produced by titanium dioxide during the reaction are considered to be the most active oxide species. The Ti–O–O–H species on the surface formed from the coordination reaction between TiO 2 and H 2 O 2 48,69 (this is also shown in Fig. S17, ESI†).…”

“…45 But the preparation of ODS catalysts using a titanium–silicon composite oxide modified H-β zeolite as a support loaded with POMs has not been reported in the literature. On the basis of previous experiments, 46–50 ODS catalysts loaded with POMs of different structural types were prepared using the impregnation method using H-β-modified catalysts as supports in this paper. Among various supported POM catalysts with different structures, modified H-β composite catalysts loaded by Keggin-type HPW showed excellent ODS performance.…”