Acidity and active sites of Al-MCM-41

1999 ◽  
Vol 184 (1) ◽  
pp. 49-60 ◽  
Author(s):  
H Kosslick ◽  
G Lischke ◽  
B Parlitz ◽  
W Storek ◽  
R Fricke
Keyword(s):  
2019 ◽  
Vol 9 (3) ◽  
pp. 811-821 ◽  
Author(s):  
Zhao-Meng Wang ◽  
Li-Juan Liu ◽  
Bo Xiang ◽  
Yue Wang ◽  
Ya-Jing Lyu ◽  
...  

The catalytic activity decreases as –(SiO)3Mo(OH)(O) > –(SiO)2Mo(O)2 > –(O)4–MoO.


RSC Advances ◽  
2020 ◽  
Vol 10 (50) ◽  
pp. 30214-30222
Author(s):  
Bolong Jiang ◽  
Jiaojing Zhang ◽  
Yanguang Chen ◽  
Hua Song ◽  
Tianzhen Hao ◽  
...  

Co3O4/MCM-41 adsorbent with high surface area and more active sites was successfully prepared by ultrasonic assisted impregnation (UAI) technology and it has been found that the sulfur capacity was improved by 33.2% because of ultrasonication.


2020 ◽  
pp. 174751982092599
Author(s):  
Heng Zhang ◽  
Chunhao Yang ◽  
Shengying Zhao ◽  
Tingting Wang ◽  
Wancheng Zhu

Ordered mesoporous silica, SBA-15 and MCM-41, and three-dimensionally ordered macroporous SiO2 were used as the supports of H4PMo11VO40 heteropolyacid for methacrolein oxidation. The dispersion and structural evolutions of the heteropolyacid along with thermal treatment were investigated. It was found that the heteropolyacid entered the one-dimensional mesoporous channels of SBA-15 and MCM-41, and the crystallization and growth were limited, leading to high dispersion of the heteropolyacid. However, the thermal stability was decreased under high dispersion. The migration of the heteropolyacid was observed to the end of the one-dimensional channels of SBA-15 and the outer surface of MCM-41 with calcination, accompanied by the decomposition of the heteropolyacid and the formation of MoO3. In comparison, the crystallization and growth of heteropolyacid were not limited in the open macropores of three-dimensionally ordered macroporous SiO2. Dispersed particles on the surface of the macropores with size of about 5 nm exhibited a higher thermal stability. The decomposition of the heteropolyacid in the SBA-15 and MCM-41 supported catalysts resulted in the loss of strong acid sites, causing low selectivity to methacrylic acid in methacrolein oxidation. High thermal stability with high exposure of the active sites in the three-dimensionally ordered macroporous SiO2 supported catalyst contributed to the enhancement in the catalytic performance.


2020 ◽  
Vol 10 (1) ◽  
pp. 278-290 ◽  
Author(s):  
Li-Juan Liu ◽  
Zhao-Meng Wang ◽  
Ya-Jing Lyu ◽  
Jin-Feng Zhang ◽  
Zhou Huang ◽  
...  

In the V-doped Al-MCM-41 framework, the [V-1] active site with a hydroxyl group displays better catalytic activity than the [V-0] active site without a hydroxyl group toward the oxidation of 5-hydroxymethylfurfural to 2,5-diformylfuran.


2003 ◽  
Vol 90 (3/4) ◽  
pp. 161-163 ◽  
Author(s):  
Yun Hu ◽  
Shinya Higashimoto ◽  
Gianmario Martra ◽  
Jinlong Zhang ◽  
Masaya Matsuoka ◽  
...  

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Shang-Yuan Cheng ◽  
You-Zhi Liu ◽  
Gui-Sheng Qi

Microwave synthesis method is a green chemical process with mild reaction conditions, fast reaction, and low energy consumption. In this work, an order mesoporous silica material MCM-41 was synthesized by microwave technology. Functionalized MCM-41 was prepared by wet impregnation with polyethyleneimine (PEI). XRD, SEM, TEM, DLS, N2 adsorption-desorption, FTIR, and TG were used to characterize the physicochemical properties of samples. Furthermore, CO2 absorption performance in water in the presence of uncalcined MCM-41 and PEI-MCM-41 nanoparticles was evaluated. In addition, the mechanisms of enhanced absorption were also elaborated. The experimental results indicated that the optimum conditions for preparation of MCM-41 were the microwave time of 15 min, microwave temperature of 100°C, and microwave power of 200 W. Under this condition, MCM-41 with narrow particle size distribution, average diameter of 50 nm, and SBET of 1210.3 m2g-1 was obtained. The enhancement effect of PEI-MCM-41 nanoparticles was more obvious than that of uncalcined MCM-41. PEI-MCM-41 as a promoter not only increased the CO2 diffusion rate but also enhanced the adsorption capacity due to the fact that it owns more active sites that may react with CO2. The CO2 absorption improvement of PEI-MCM-41 (0.1 wt%)/H2O was 25.35% higher than that of water.


RSC Advances ◽  
2015 ◽  
Vol 5 (88) ◽  
pp. 72099-72106 ◽  
Author(s):  
Fu Yang ◽  
Shuying Gao ◽  
Cuirong Xiong ◽  
Saifu Long ◽  
Xiaoming Li ◽  
...  

Understanding the nature of active sites, including the number and dispersion on the surface of a support, is essential to improve the catalytic activity.


ACS Catalysis ◽  
2017 ◽  
Vol 7 (3) ◽  
pp. 1646-1654 ◽  
Author(s):  
Laura Collado ◽  
Ingrid Jansson ◽  
Ana E. Platero-Prats ◽  
Virginia Perez-Dieste ◽  
Carlos Escudero ◽  
...  

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