Synthesis of a highly active oxidation catalyst with improved distribution of titanium coordination states

Wu, Lizhi; Deng, Xiujuan; Zhao, Shufang; Yin, Hui; Zhuo, Zuoxi; Fang, Xiangqing; Liu, Yueming; He, Min

doi:10.1039/c6cc03318k

Cited by 91 publications

(64 citation statements)

References 37 publications

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“…There were two peaks located at the 2 θ of 24.4° in the H−S‐1 whereas there are unimodal peaks in microporous m‐TS‐1, H−S‐1@TS‐1 and M‐m‐TS‐1, indicating the coverage of the monoclinic syngony of silicalite‐1 by the orthorhombic syngony of TS‐1. This is an indirect proof for the insertion of titanium to the framewok ,…”

Section: Methodsmentioning

confidence: 78%

The High-Performance Hollow Silicalite-1@Titanium Silicalite-1 Core-Shell Catalyst for Propene Epoxidation

et al. 2017

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Hollow silicalite‐1@titanium silicalite‐1 (H−S‐1@TS‐1) core‐shell catalyst was synthesized in hydrothermal system with hollow silicalite‐1 serving as core. In this novel method, tetrapropylammonium hydroxide (TPAOH) served as the single template in the whole synthesis process so as to avoid secondary structure directing agents (SDAs) that traditional methods applied to give core‐shell TS‐1. Since inner hollow structure was given by S‐1, H−S‐1@TS‐1 avoided framework Ti leaching in coventional dissolution‐recrystallization process that gave hollow TS‐1 and thus it was in absence of extra‐framework Ti. H−S‐1@TS‐1 showed better propene epoxidation activity (TOF=13.61 mol (mol h)−1) than microporous TS‐1 (TOF=8.08 mol (mol h)−1) and micro‐TS‐1 post‐treated with TPAOH solution (TOF=9.75 mol (mol h)−1) due to the synergy function of pure framework Ti species, higher surface Ti content and enhanced diffusion property.

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Section: Methodsmentioning

confidence: 78%

The High-Performance Hollow Silicalite-1@Titanium Silicalite-1 Core-Shell Catalyst for Propene Epoxidation

et al. 2017

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“…This band is also present in the MFI TS‐1B material, synthesized by Balducci et al . or TS‐1+ zeolite synthesized by L. Wu et al . It was suggested by Wu et al .…”

Section: Resultsmentioning

confidence: 99%

Incorporation of Ti as a Pyramidal Framework Site in the Mono‐Layered MCM‐56 Zeolite and its Oxidation Activity

et al. 2018

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MWW zeolite MCM‐56 with Al atoms on the surface was functionalized with Ti to produce pyramidal TiOH groups. This was carried out by removal of Al with nitric acid, calcination and treatment with titanium diisopropoxide bis(acetylacetonate) (Ti(acac)2 (i‐propoxide)2, Ti(acac)2OiPr2). Up to 0.7 % Ti was introduced. Using UV‐Vis spectroscopy three types of Ti moieties were identified in the uncalcined materials – tetrahedral in the framework, 5/6‐coordinated Ti on the surface, presumably in the vacated pyramidal sites, and oxide‐like clusters. The presence of TiOH on the surface was indicated by in situ measurement of UV‐Vis spectra during calcination. It showed the band at 290 nm, which disappeared at 500 °C, perhaps due to condensation with silanols. Catalytic oxidation tests were carried out with three samples containing 0.13, 0.36, and 0.70 % Ti and methyl phenyl sulfide and cis‐cyclooctene as model reactants. The study confirmed potential of the TiOH moieties in oxidation catalysis although their final form is not certain. Future studies will include increasing Ti content to enhance catalytic activity and better detection of this type of the Ti site.

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“…Moreover, considering the possibility of modifying Ti-MWW with respect to both the structure and microenvironment of Ti active sites, Ti-MWW was further studied. The PI-assisted arrangement has been reported to be an effective way to enhance the catalytic performance of Ti-MWW zeolites in the epoxidation reactions of alkenes (Wu et al, 2016). Thus, in the present case of cyclopentene, PIassisted structural modification was also performed.…”

Section: A Comparison Of the Catalytic Performance Over A Series Of Tmentioning

confidence: 98%

“…Xu et al (2020) reported the one-step rapid synthesis of TS-1 with mononuclear TiO 6 species affording a high turnover number value of 272 in the 1-hexene epoxidation reaction. Wu et al (2016) illustrated that the mononuclear "TiO 6 " species showed the catalytic activity 2-3 times that of the "TiO 4 " species in TS-1 for the epoxidation of alkenes.…”

Section: Introductionmentioning

confidence: 99%

Modified Ti-MWW Zeolite as a Highly Efficient Catalyst for the Cyclopentene Epoxidation Reaction

et al. 2020

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The liquid-phase epoxidation of cyclopentene (CPE) was performed in the Ti-zeolite/H 2 O 2 catalytic system for the clean synthesis of cyclopentene oxide. Among all the Ti-zeolites (Ti-Beta, Ti-MOR, Ti-MCM-68, TS-1, TS-2, and Ti-MWW) investigated in the present study, Ti-MWW provided relatively lower CPE conversion of 13% due to the diffusion constrains but a higher CPO selectivity of 99.5%. The catalytic performance of Ti-MWW was significantly enhanced by piperidine (PI) treatment, with the CPE conversion and CPO selectivity increased to 97.8 and 99.9%, respectively. The structural rearrangement upon PI treatment converted the 3-dimensional (3D) MWW structure to a 2D lamellar one, which enlarged the interlayer space and greatly alleviated the diffusion constrains of cyclic cyclopentene. Furthermore, the newly constructed "open site" six-coordinated Ti active sites with PI as the ligand exhibited higher catalytic activity. The two factors contributed to more significant enhancement of the activity upon PI-assisted structural arrangement compared to the cases in linear alkenes.

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Synthesis of a highly active oxidation catalyst with improved distribution of titanium coordination states

Cited by 91 publications

References 37 publications

The High-Performance Hollow Silicalite-1@Titanium Silicalite-1 Core-Shell Catalyst for Propene Epoxidation

The High-Performance Hollow Silicalite-1@Titanium Silicalite-1 Core-Shell Catalyst for Propene Epoxidation

Incorporation of Ti as a Pyramidal Framework Site in the Mono‐Layered MCM‐56 Zeolite and its Oxidation Activity

Modified Ti-MWW Zeolite as a Highly Efficient Catalyst for the Cyclopentene Epoxidation Reaction

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