Isomerization of Norbornadiene to Quadricyclane Using Ti-Containing MCM-41 as Photocatalysts

Zou, Ji‐Jun; Zhang, Mingyue; Zhu, Bin; Wang, Li; Zhang, Xiangwen; Mi, Zhentao

doi:10.1007/s10562-008-9441-5

Cited by 27 publications

(10 citation statements)

References 22 publications

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“…The Zr‐incorporated MCM‐41 support (abbreviated as ZrM) was synthesized according to our previous work [ 51‐52 ] with modification. Typically, 50 mL of NaOH solution (0.21 mol/L) in a three‐ necked round‐bottom flask was heated at 50°C under magnetic stirring, after which 1.82 g of CTAB was dissolved in it.…”

Section: Methodsmentioning

confidence: 99%

Framework Zr Stabilized PtSn/Zr‐MCM‐41 as a Promising Catalyst for Non‐oxidative Ethane Dehydrogenation

Shi

Zhang

et al. 2022

Chin. J. Chem.

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Comprehensive Summary Non‐oxidative ethane dehydrogenation is a promising route to produce ethene. Herein, PtSn supported catalysts were investigated to achieve better ethane dehydrogenation performance by introduction of different Zr promoters, i.e., framework Zr and ZrO2, to mesoporous MCM‐41. In‐situ XRD, TEM and CO chemisorption show that aggregation of metal particles and phase segregation of Pt3Sn to Pt and PtSn3 at high temperature occur for PtSn/M, leading to bad ethane dehydrogenation activity. Strong interaction between ZrO2 and PtSn species, as proved by XPS, results in restrained metal particles, which promotes the initial reactivity. However, Pt phase generated on surface is disadvantageous for the desorption of produced ethene as indicated by CO‐IR and C3H6‐TPD, and pyridine‐IR and NH3‐TPD indicate strong acidity generated. Both deactivate the catalyst rapidly by deep dehydrogenation and coking. Moderate interaction between PtSn species and Si‐O‐Zr with much weaker acidity is formed when framework Zr is incorporated into MCM‐41, which benefits the dispersion of metal particles, formation of Pt3Sn/Pt species and stabilization of metal species from phase segregation. Outstanding initial ethane conversion and ethene selectivity of ca. 99% were achieved for the optimal PtSn/ZrM, which is more coking‐tolerant and stable by generating graphitic carbon mainly on support instead of active metals.

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Section: Methodsmentioning

confidence: 99%

Framework Zr Stabilized PtSn/Zr‐MCM‐41 as a Promising Catalyst for Non‐oxidative Ethane Dehydrogenation

Shi

Zhang

et al. 2022

Chin. J. Chem.

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“…21 The pair of chemicals QD and NB (and their derivatives) was considered for solar energy storage. [22][23][24] The photoinduced isomerization of NB results in QD, and when converted back into NB, the strain energy is liberated as heat ( H = −89 kJ/mol). 25 The NB and QD isomers may also form the molecular basis for an optical memory system.…”

Section: Introductionmentioning

confidence: 99%

Ultrafast structural and isomerization dynamics in the Rydberg-exited Quadricyclane: Norbornadiene system

Rudakov

Weber

2012

The Journal of Chemical Physics

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The quadricyclane-norbornadiene system is an important model for the isomerization dynamics between highly strained molecules. In a breakthrough observation for a polyatomic molecular system of that complexity, we follow the photoionization from Rydberg states in the time-domain to derive a measure for the time-dependent structural dynamics and the time-evolving structural dispersion even while the molecule is crossing electronic surfaces. The photoexcitation to the 3s and 3p Rydberg states deposits significant amounts of energy into vibrational motions. We observe the formation and evolution of the vibrational wavepacket on the Rydberg surface and the internal conversion from the 3p Rydberg states to the 3s state. In that state, quadricyclane isomerizes to norbornadiene with a time constant of τ(2) = 136(45) fs. The lifetime of the 3p Rydberg state in quadricyclane is τ(1) = 320(31) and the lifetime of the 3s Rydberg state in norbornadiene is τ(3) = 394(32).

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“…The M41S family of mesoporous molecular sieves has attracted extensive attention of many researchers since their discovery in 1990s. , On behalf of these materials, MCM-41 is an important class of a hexagonally arranged cylindrical pores with a large surface area, regular pore diameters, and high thermal stability. Thus, these properties make MCM-41 material suitable for many catalytic applications, such as isomerization, , selective oxidation, − photocatalysis, − and so forth. As reported, the incorporation of heteroatoms in MCM-41 could generate new acidity wherein Lewis and Brönsted acid sites are involved. − The heteroatom-submitted MCM-41 has opened opportunities to obtain new acid sites for catalytic applications.…”

Section: Introductionmentioning

confidence: 99%

Effect of Sulfate Modification on Structure Properties, Surface Acidity, and Transesterification Catalytic Performance of Titanium-Submitted Mesoporous Molecular Sieve

Wang

Shi

2012

Ind. Eng. Chem. Res.

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A series of sulfated titanium-submitted mesoporous molecular sieves denoted as S/Ti-MCM-41 were prepared by wet impregnation method with H 2 SO 4 solution as promoter. The results of XRD, N 2 adsorption−desorption, NH 3 -TPD, FTIR of pyridine adsorption, and XPS analysis indicated that S/Ti-MCM-41 samples possess well-ordered hexagonal mesostructure, although the pore diameter and specific surface area shrunk with the increasing coverage of sulfur species. As a result of the electron inductive effect from the SO bond of SO 4 2− , Lewis acidity is intensified significantly and new Bronsted acid sites are generated from the activated hydroxyl groups. Bronsted acid sites are medium strength, while part of the Lewis acid sites are of weak strength and part of them are medium. The S/Ti-MCM-41 catalysts exhibited desirable activity for transesterification of dimethyl oxalate and phenol. INTRODUCTIONThe M41S family of mesoporous molecular sieves has attracted extensive attention of many researchers since their discovery in 1990s. 1,2 On behalf of these materials, MCM-41 is an important class of a hexagonally arranged cylindrical pores with a large surface area, regular pore diameters, and high thermal stability. Thus, these properties make MCM-41 material suitable for many catalytic applications, such as isomerization, 3,4 selective oxidation, 5−7 photocatalysis, 8−10 and so forth. As reported, the incorporation of heteroatoms in MCM-41 could generate new acidity wherein Lewis and Bronsted acid sites are involved. 11−14 The heteroatom-submitted MCM-41 has opened opportunities to obtain new acid sites for catalytic applications. Concerning the improvement of acidity, on the other hand, the sulfurcontaining catalysts are of interest because the modification of sulfate species has been reported to enhance both strength and amount of acidity on the surface of molecular sieves and metal oxide catalysts. 15−17 Many of studies were carried out for the synthesis of Ti-MCM-41 catalysts. 5,15−21 To the best of our knowledge, however, there are no reports on sulfated Ti-MCM-41 preparation. In this work, titanium containing MCM-41 material was prepared with the microwave irradiation method and modified by H 2 SO 4 aqueous solutions to further improve the acidity. The structure and acid properties of the materials were characterized with XRD, N 2 adsorption−desorption, NH 3 -TPD and FT-IR of pyridine adsorption, and XPS analysis. Transesterification of dimethyl oxalate (DMO) with phenol, as an acid catalyzed reaction, was employed as a probe reaction to test the effects of sulfate modification on acid catalytic properties. In this route, DPO is synthesized via two steps; namely, the transesterification of DMO with phenol into methyl phenyl oxalate (MPO) (eq 1) followed the disproportionation reaction of MPO to DPO (eq 2), while a major byproduct during the above process was anisole (AN),

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Isomerization of Norbornadiene to Quadricyclane Using Ti-Containing MCM-41 as Photocatalysts

Cited by 27 publications

References 22 publications

Framework Zr Stabilized PtSn/Zr‐MCM‐41 as a Promising Catalyst for Non‐oxidative Ethane Dehydrogenation

Framework Zr Stabilized PtSn/Zr‐MCM‐41 as a Promising Catalyst for Non‐oxidative Ethane Dehydrogenation

Ultrafast structural and isomerization dynamics in the Rydberg-exited Quadricyclane: Norbornadiene system

Effect of Sulfate Modification on Structure Properties, Surface Acidity, and Transesterification Catalytic Performance of Titanium-Submitted Mesoporous Molecular Sieve

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