One-pot synthesis of ordered mesoporous Cu-KIT-6 and its improved catalytic behavior for the epoxidation of styrene: Effects of the pH value of the initial gel

Li, Baitao; Luo, Xin; Huang, Jing; Wang, Xiujun; Liang, Zhenxing

doi:10.1016/s1872-2067(17)62767-0

Cited by 33 publications

(9 citation statements)

References 91 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The pore size distribution can be tuned by varying the hydrothermal treatment temperature. In order to incorporate metal ions (such as Ti, Cu, Ga, La, B, Fe) under acidic conditions, the pH of the synthesis mixture is typically adjusted by lowering the acid concentrations (0.1–0.5 M HCl) [ 15 , 20 , 21 , 22 , 23 ]. We have successfully incorporated W, Zr, and Nb by adding the respective metal salts to the synthesis mixture of siliceous KIT-6 without any pH adjustments [ 24 , 25 , 26 , 27 ].…”

Section: Methodsmentioning

confidence: 99%

Metal-Incorporated Mesoporous Silicates: Tunable Catalytic Properties and Applications

Ramanathan

Subramaniam

2018

Molecules

View full text Add to dashboard Cite

A relatively new class of three-dimensional ordered mesoporous silicates, KIT-6, incorporated with Earth-abundant metals such as Zr, Nb, and W (termed as M-KIT-6), show remarkable tunability of acidity and metal dispersion depending on the metal content, type, and synthetic method. The metal-incorporation is carried out using one-pot synthesis procedures that are amenable to easy scale-up. By such tuning, M-KIT-6 catalysts are shown to provide remarkable activity and selectivity in industrially-significant reactions, such as alcohol dehydration, ethylene epoxidation, and metathesis of 2-butene and ethylene. We review how the catalytic properties of M-KIT-6 materials may be tailored depending on the application to optimize performance.

show abstract

Section: Methodsmentioning

confidence: 99%

Metal-Incorporated Mesoporous Silicates: Tunable Catalytic Properties and Applications

Ramanathan

Subramaniam

2018

Molecules

View full text Add to dashboard Cite

show abstract

“…Considering the asymmetry of the Cu2p 3/2 envelope, these peaks could be deconvoluted into two peaks centered at around 933.7 eV and 936.2 eV, which implies the existence of two Cu 2+ species in different chemical environments. The former corresponds to free CuO species, while the latter belongs to CuO with strong interaction with promoters [30,31,32]. The higher binding energy (936.2 eV) suggests a charge transfer from Cu 2+ ions toward the promoter [32].…”

Section: Resultsmentioning

confidence: 99%

“…The former corresponds to free CuO species, while the latter belongs to CuO with strong interaction with promoters [30,31,32]. The higher binding energy (936.2 eV) suggests a charge transfer from Cu 2+ ions toward the promoter [32]. Notably, the 936.2 eV peak in the spectrum of Cu 0.84 Al 0.16 is apparently the strongest among the catalysts, which is possibly due to stronger interactions between CuO and Al 2 O 3 than those involving other promoters.…”

Section: Resultsmentioning

confidence: 99%

Ethynylation of Formaldehyde over Binary Cu-Based Catalysts: Study on Synergistic Effect between Cu+ Species and Acid/Base Sites

et al. 2019

View full text Add to dashboard Cite

Most studies on the Cu-based catalysts in the ethynylation of formaldehyde are merely focused on the tuning of electronic configuration and dispersion of the Cu+ species. So far, little attention has been paid to the synergy between Cu species and promoters. Herein, binary nano-CuO-MOx catalysts (M = Si, Al, and Mg) were synthesized and the effects of the promoter on the surface basicity/acidity were systematically studied as well as the ethynylation performance of the nano-CuO-based catalysts. The results show that the introduction of MgO provided a large number of basic sites, which could coordinate with the active Cu+ species and facilitate the dissociation of acetylene as HC ≡ Cδ− and Hδ+. The strongly nucleophilic acetylenic carbon (HC≡Cδ−) is favorable to the attack at the electropositive carbonyl Cδ+ of formaldehyde. The MgO-promoted CuO catalyst showed the highest yield of BD (94%) and the highest stability (the BD yield decreased only from 94% to 82% after eight reaction cycles). SiO2 effectively dispersed Cu species, which improved catalytic activity and stability. However, the introduction of Al2O3 resulted in a large number of acidic sites on the catalyst’s surface. This led to the polymerization of acetylene, which covered the active sites and decreased the catalyst’s activity.

show abstract

“…The asymmetric Cu 2p 3/2 peaks of all the catalysts can be fitted into two peaks centered at 936.0 eV and 933.9 eV, indicating there were two distinct types of Cu 2+ species in the supported catalysts. Cu 2+ species centered at 933.9 eV are due to the bulk CuO and the higer BE ones at 936.0 eV are attributed to the well-dispersed Cu 2+ ions interacting with the support [46,53]. It can be seen from the change of the fitting peaks of Cu 2p 3/2 that for CuO/SiO 2 -MgO samples, Cu 2+ species at 936.0 eV reach the maximum and the main body of the Cu 2p 3/2 peak shifted to the higher binding energy, indicating the stronger interaction between copper species and the support.…”

Section: Resultsmentioning

confidence: 99%

“…All samples exhibited two reduction peaks α (around 200 °C) and β (around 250 °C) indicating the existence of two kinds of CuO species, which is consistent with the results of XPS. It is considered that the α peak is due to the small Cu 2+ species interacted with supports, and the β peak is ascribed to the reduction of the larger CuO particles [46,53]. The area ration of peaks α and β followed the sequence of CuO/SiO 2 -MgO > CuO/SiO 2 > CuO/MgO/SiO 2 , suggesting the size decrease and better dispersion of the CuO particles, which is well consistent with the XRD and TEM results.…”

Section: Resultsmentioning

confidence: 99%

Ethynylation of Formaldehyde over CuO/SiO2 Catalysts Modified by Mg Species: Effects of the Existential States of Mg Species

et al. 2019

View full text Add to dashboard Cite

The highly effective catalytic synthesis of 1,4-butynediol (BD) from the Reppe process is a fascinating technology in modern chemical industry. In this work, we reported the effects of the existential states of Mg species in the CuO/silica-magnesia catalysts for the ethynylation of formaldehyde in a simulative slurry reactor. The physichemical properties of the supports and the corresponding catalysts were extensively characterized by various techniques. The experimental results indicated that the introduced Mg species in the form of MgO particles, MgO microcrystals, or Si-O-Mg structures effectively resulted in an abundance of medium-strong basic sites, which can synergize with the active Cu+ species, facilitate the activation of acetylene, and improve the ethynylation activity. For the CuO/MgO-SiO2 catalyst, the existence of Si-O-Mg structures strengthened the Cu–support interaction, which were beneficial to improving the dispersion and the valence stability of the active Cu+ species. The highly dispersed Cu+ species, its stable valence state, and the abundant medium-strong basic sites enhanced the synergistic effect significantly, leading to the superior activity and stability of CuO/MgO-SiO2. The insights into the role of the existential states of Mg species and the revelation of the synergistic effect between active Cu+ species and basic sites can provide theoretic guidance for future rational design of catalysts for the ethynylation reation.

show abstract

One-pot synthesis of ordered mesoporous Cu-KIT-6 and its improved catalytic behavior for the epoxidation of styrene: Effects of the pH value of the initial gel

Cited by 33 publications

References 91 publications

Metal-Incorporated Mesoporous Silicates: Tunable Catalytic Properties and Applications

Metal-Incorporated Mesoporous Silicates: Tunable Catalytic Properties and Applications

Ethynylation of Formaldehyde over Binary Cu-Based Catalysts: Study on Synergistic Effect between Cu+ Species and Acid/Base Sites

Ethynylation of Formaldehyde over CuO/SiO2 Catalysts Modified by Mg Species: Effects of the Existential States of Mg Species

Contact Info

Product

Resources

About