Acidity and active sites of Al-MCM-41

Kosslick, H.; Lischke, G.; Parlitz, B.; Storek, W.; Fricke, R.

doi:10.1016/s0926-860x(99)00078-2

Cited by 155 publications

(98 citation statements)

References 38 publications

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“…These results are in agreement with previous findings [29][30][31][32]. The conversion rate versus exchange degree (Figure 10) shows that the increase of exchange degree causes an increase in catalytic activity and that the highest activity was observed for the H(95)MCM-41.…”

Section: Catalytic Properties Of Mcm-41 Materialssupporting

confidence: 93%

<b>CATALYTIC PROPERTIES AND ACIDITY OF MODIFIED MCM-41 MESOPOROUS MATERIALS WITH LOW Si/Al RATIO: HEPTANE ISOMERISATION</b>

Belhakem

Bengueddach

2006

Bull. Chem. Soc. Eth.

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ABSTRACT. The catalytic properties and acidity of modified MCM-41 with a low Si/Al ratio and 0-95% NH 4 + exchange were investigated. The samples were characterised by X-ray diffraction, scanning and transmission electron microscopy, and nitrogen adsorption. The acidity was studied by pyridine adsorption, temperature programmed desorption (TPD) of ammonia, and infrared (IR) spectroscopy. Adsorption of pyridine and IR spectroscopy indicated various types of Lewis and Brönsted acid sites. The density distribution of acid sites was determined by TPD. Both Lewis and Brönsted acid sites were found to be active in the heptane isomerisation. The presence of aluminium (low Si/Al) combined to the ionic exchange between Na + and NH 4 + increases the acidity of MCM-41 materials. A close correlation between acidity and isomerisation was observed. Coke deposition, which reduces the activity, was also studied.

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Section: Catalytic Properties Of Mcm-41 Materialssupporting

confidence: 93%

<b>CATALYTIC PROPERTIES AND ACIDITY OF MODIFIED MCM-41 MESOPOROUS MATERIALS WITH LOW Si/Al RATIO: HEPTANE ISOMERISATION</b>

Belhakem

Bengueddach

2006

Bull. Chem. Soc. Eth.

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“…A good example of this would be Al-MCM-41 in which the incorporation of aluminum in the structure of the otherwise catalytically inert silica-based MCM-41 makes it active for some acid-catalyzed reactions. [6] However, in the last few years the field of functional mesoporous materials-many examples of which have been prepared with other applications in mind-has grown considerably opening-up new opportunities for some challenging and important catalytic chemical process.…”

Section: /2013mentioning

confidence: 99%

Editorial: From Mesoporous Supports to Mesoporous Catalysts: Introducing Functionality to Mesoporous Materials

Luque

Martı́nez

2013

ChemCatChem

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“…These studies provide a clue that reusable ammonia detection materials can be fabricated using the porous material as a matrix to produce chemosensing reagents. More recently, ordered mesoporous silica materials are of interest for several applications, due to uniform nanoporosity, mechanical stiffness, thermal stability, high surface area and pore volume, tunable pore size, and the possibility of incorporation of heteroatoms into the silica structure (Kosslick et al, 1999;Kresge et al, 1992;Matsumoto et al, 1999). The nonflammable porous silica-based material is better than the flammable carbonbased material when safety is of concern.…”

mentioning

confidence: 99%

“…They possess the unique properties of uniform nanoporosity, large surface area, high regenerative ability and high thermal stability (Kosslick et al, 1999;Kresge et al, 1992;Matsumoto et al, 1999). These two materials are sensitive upon exposure to the ammonia gas-containing environment (Fiorlli et al, 2004;Wark et al, 2003).…”

mentioning

confidence: 99%

Development of regenerative dye impregnated mesoporous silica materials for assessing exposure to ammonia

Chang

Bai

Chiang

et al. 2012

Journal of the Air & Waste Management Association

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The mesostructured materials MCM-41 and SBA-15 were studied as possible supports of bromocresol green (BG) dye impregnation for the ammonia gas detection because of their large surface area, high regenerative property, and high thermal stability. X-ray diffraction, transmission electron microscopy, scanning electron microscope, and N 2 adsorption analysis were used to characterize the prepared materials. These materials could sense ammonia via visible color change from yellowish-orange to blue color. The color change process of the nanostructured materials was fully reversible during 10 cyclic tests. The results indicated that the ammonia absorption responses of the two nanostructured materials were both very sensitive, and high linear correlation and high precision were achieved. As the gaseous ammonia concentrations were 50 and 5 ppmv, the response times for the SBA-15/BG were only 1 and 5 min, respectively. Moreover, the BG dye-impregnated SBA-15 was less affected by the variation in the relative humidity. It also had faster response for the detection of NH 3 , as well as lower manufacturing price as compared to that of the dyeimpregnated MCM-41. Such feature enables SBA-15/BG to be a very promising material for the detection of ammonia gas. Implications:The detector tube is a convenient ambient ammonia detection device. However, almost all the commercial detector tubes can be used once only, which not only increases the purchase cost but also produces lots of waste. In this study, we developed two sensing materials that are sensitive for repeated usage. The two mesoporous silica-based materials, MCM-41 and SBA-15, are impregnated by an organic dye of bromocresol green to induce color change behavior that can be easily observed by the naked eye, and it is concluded that dye-impregnated SBA-15/BG is a very promising material for the detection of ammonia gas.

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Acidity and active sites of Al-MCM-41

Cited by 155 publications

References 38 publications

<b>CATALYTIC PROPERTIES AND ACIDITY OF MODIFIED MCM-41 MESOPOROUS MATERIALS WITH LOW Si/Al RATIO: HEPTANE ISOMERISATION</b>

<b>CATALYTIC PROPERTIES AND ACIDITY OF MODIFIED MCM-41 MESOPOROUS MATERIALS WITH LOW Si/Al RATIO: HEPTANE ISOMERISATION</b>

Editorial: From Mesoporous Supports to Mesoporous Catalysts: Introducing Functionality to Mesoporous Materials

Development of regenerative dye impregnated mesoporous silica materials for assessing exposure to ammonia

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