Effect of Pore Structure on the Nitridation of Mesoporous Silica with Ammonia

Hayashi, Fumitaka; Ishizu, Ken‐ichi; Iwamoto, Masakazu

doi:10.1002/ejic.200901236

Cited by 20 publications

(24 citation statements)

References 44 publications

(89 reference statements)

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“…M41 was prepared according to a reported procedure [11] by using C 12 H 25 N(CH 3 ) 3 Br as the template and colloidal silica as the silica source. Nickel ion was loaded onto M41 by the template ion exchange (TIE) method using a nickel nitrate aqueous solution.…”

Section: Methodsmentioning

confidence: 99%

“…Nickel ion was loaded onto M41 by the template ion exchange (TIE) method using a nickel nitrate aqueous solution. [8,11] As-prepared Ni-MCM-41 was calcined at 773 K for 6 h in air, in which the sample was thinly (less than 2 mm thick) spread onto a ceramic board and heated at 0.2-0.5 K min À1 . The slow heating with the shallow bed method was important to obtain good and reproducible catalytic activity.…”

Section: Methodsmentioning

confidence: 99%

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Conversion of Ethanol into Polyolefin Building Blocks: Reaction Pathways on Nickel Ion‐loaded Mesoporous Silica

2011

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The use of bioethanol (bEtOH) as an alternative (or additive) for automobile fuels has increased rapidly all over the world. This is one way of using renewable resources to suppress carbon dioxide emissions, while another challenge is the conversion of bEtOH to various olefins and their use for production of chemicals and polymers. [1][2][3][4][5][6][7] The latter would be very significant for the long-term fixation of carbon dioxide. Many efforts have therefore been devoted to the development of systems for converting bEtOH to ethene (C2 = ) and other lower olefins. In particular conversion to propene (C3 = ) is desirable due to the greater demand for C3= derivatives, such as propene oxide, acrylonitrile, and polypropene.[2]Catalytic conversions of EtOH on zeolites [3][4][5] and metal oxides [6, 7] have been widely studied. On zeolites, the activity and selectivity in the many studies reported so far are insufficient. The major weakness is catalyst deactivation. For example, the selectivity towards C3 = on proton-or metal-modified zeolites is usually ca. 20-30 % and decreases with reaction time, although sometimes higher C3 = selectivity values are observed upon catalyst degradation. [3][4][5] Oligomerization, polymerization, and fission reactions on strong acid sites in zeolite pores result in the formation of C3 = and butenes (C4 = ) due to shape selectivity. [3][4][5] However, the random reactions in the pores finally result in coke formation and short catalyst life times. EtOH can also react on metal oxide surfaces to give various chemicals. Acid sites are widely recognized to lead to dehydration of EtOH, giving C2 = , while basic sites lead to dehydrogenation to yield acetaldehyde (AA). [6, 7] As a result, many kinds of products, for example aldehydes, ketones, C2 [8] Therefore, Ni-M41 is a possible catalyst for the conversion of EtOH to C3 = since M41 is active for the dehydration of EtOH to yield C2 = .[8b] Indeed, this was confirmed by preliminary results from our group [9] and subsequently by Sugiyama et al.[10] The pore diameters of M41 are usually 1.5-5.0 nm, and, therefore the product distribution on the catalysts is not controlled by shape selectivity. The reaction mechanism/pathways are of interest, and the target of our present study.The influence of temperature on EtOH conversion over Ni-M41 is summarized in Figure 1. Many kinds of products were formed in addition to C2 = . Diethylether (DEE) was mainly obtained at around 523 K. DEE has been reported earlier as an intermediate compound in the dehydration, decomposing to yield EtOH and C2= at higher temperatures.[8b] The C2 = yield sharply increased at 573 K, and reached ca. 70 % at 623 K or above. The C4 = yield reached a maximum at 623 K, while maxima in C3 = yield occurred at 673 and 723 K. Notably, AA was formed at 573-723 K, although not in large amounts, which will be discussed later. The stability of Ni-M41 was examined at 673 K. As shown in Figure 2, the catalytic activity did not change during 20 h of continuous time on stream. In addi...

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Conversion of Ethanol into Polyolefin Building Blocks: Reaction Pathways on Nickel Ion‐loaded Mesoporous Silica

2011

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“…Finally, the surface areas of porous TiO 2 -based composite oxides obtained in this work were compared in consideration of the respective wall densities. Mesoporous silica MCM-41, prepared by using CTAB [39], with a surface area of 941 m 2…”

Section: Expansion Of the Wie-calcination Methods To The Preparation Omentioning

confidence: 99%

Preparation of porous MTiO (M = Cr, Mo, or W) composite oxides from a mesostructured material of titanium oxysulfate and surfactant micelles based on a wall ion exchange–calcination method

Tanaka

Suh

Takada

et al. 2015

Microporous and Mesoporous Materials

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Wall ion exchange (WIE) and subsequent calcination were applied to prepare porous TiO 2-based composite oxides using a composite of TiOSO 4 •xH 2 SO 4 •xH 2 O and cetyltrimethylammonium bromide (TS). Chromium oxyanion HCrO 4 in an aqueous solution was ion-exchanged stoichiometrically with HSO 4 in TS at pH values in the range of 2.2 to 5.5. Calcination of the HCrO 4-introduced TS (Cr-TS) at 673 K for 2 h in air produced Cr-Ti oxide with surface areas of 296-430 m 2 g-1 , pore diameters of 1.7-2.5 nm, and a wormhole-like pore structure. These high surface areas could be achieved at ratios of Cr and Ti in the Cr-Ti oxide of 0.30-0.39 or above. XAFS, FT-IR, and UV-vis diffuse reflectance spectra indicated the occurrence of dimerization of HCrO 4 to Cr 2 O 7 2during drying of the Cr-TS. The Cr 2 O 7 2species was then reduced to Cr(III) species upon calcination at 473-573 K. The Cr(III) species located on the

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“…In addition, these values can be compared with those of mesoporous silica MCM-41 prepared by using the same surfactant, 3.3-3.8 and 0.8-1.0 nm. [31][32][33][34] One can recognize the latter pore diameters and wall thicknesses are much larger and thinner than those of the Zrbased oxides. The difference would result from interactions of the cationic surfactants with metal oxyanions and the existence of sulfate ions in the ZS wall.…”

Section: Preparation Of Various Mo X -Zro 2 Materialsmentioning

confidence: 97%

“…The MCM-41 prepared by using CTAB showed a surface area of 941 m 2 g -1 , [31] the wall density of which was assumed to be the same as that of cristobalite (ρ SiO 2 , 2.20 g cm -3 ). The wall densities of M-ZS (M = W, Cr, Mo, V, Mn, Re, and P), ρ M-ZS , were calculated by Equation (3) Table 2.…”

Section: Preparation Of Various Mo X -Zro 2 Materialsmentioning

confidence: 99%

Preparation of Porous ZrO₂‐Based Composite Oxides Containing W, Cr, Mo, or V Through a Wall Ion‐Exchange Method

et al. 2013

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Keywords: Ion exchange / Composite oxides / Microporous materials / Zirconium / Tungsten MO x -ZrO 2 (M = W, Cr, Mo, or V) composite oxides with high surface areas and hexagonal pore structures were prepared through a wall ion-exchange (WIE)-calcination method. A composite (ZS) of Zr(SO 4 ) 2 ·4H 2 O and cetyltrimethylammonium bromide with ordered hexagonal structure was cast into solutions of M oxyanions. The efficiency of the WIE treatment was first studied on the solutions of tungsten oxyanion in detail. The surface areas of tungsten-oxyanion-introduced ZSs (W-ZSs) after calcination at 673 K in air for 2 h were 3-248 m 2 g -1 depending on the pH values of the exchange solutions. The treatments at pH = 5.6-10.1 resulted in the formation of porous materials with surface areas of 38-248 m 2 g -1 IntroductionZirconium oxide [1,2] and its composite oxides [3][4][5] have been employed as catalysts and supports because of their redox, acid/base, and thermal stabilities. For example, WO x -ZrO 2 and MoO x -ZrO 2 are typical solid acid catalysts with activity in the isomerization of n-alkanes, [3] alkylation of phenols, [4] and esterification.[5] The preparation of ZrO 2 -based oxides with high surface areas has thus been widely studied. Porous ZrO 2 , [6][7][8] Zr-Cr oxide (374 m 2 g -1 ), [9] ZrO 2 -MoO 3 (275 m 2 g -1 ), [10] ZrO 2 -WO 3 (228 m 2 g -1 ), [10] ZrO 2 -WO 3 (305 m 2 g -1 ), [11] VO x -ZrO 2 (340 m 2 g -1 ), [12] and MnO 2 -ZrO 2 (256 m 2 g -1 ) [13] have been reported. However, their preparation methods were specialized for the respective materials, and no versatile method has been suggested. Therefore, ZrO 2 -based oxides of 100 m 2 g -1 or lower have been used repeatedly as catalysts by others. [14][15][16] The present group has reported the wall ion-exchange (WIE) method [17][18][19][20] as a novel preparation method of hexagonally mesostructured materials, some of which gave porous oxides with hexagonal arrays of micropores and high surface areas after calcination.[ 4970and pore sizes of approximately 1.2 nm, whereas treatments at pH = 2.5-4.8 gave surface areas of 3-18 m 2 g -1 . The predominant oxyanion in the former region was a monomeric ion, WO 4 2-. The WIE-calcination method was thus applied to the preparation of Cr-, Mo-, or V-containing ZrO 2 composite oxides in which the respective monomeric oxyanions were employed as the exchange ions by adjusting the pH values of the solutions. The surface areas of calcined Cr-, Mo-, and V-ZS were 348, 251, and 229 m 2 g -1 , respectively, and pore sizes were 1.00-1.12 nm. The WIE-calcination method was proved to be a general method for the preparation of porous ZrO 2 -based oxides.(CTAB), [21] abbreviated as ZS in this study, is a starting material of the WIE treatment, and has the composition Zr(HSO 4 )(C 19 H 42 N) 0.61 (OH) 3.57 ·2H 2 O with ordered hexagonal arrays of surfactant micelles as shown in Figure 1. The hydrogen sulfate anions (HSO 4 -) in the ZS wall can be exchanged readily for oxyanions of phosphorus, [17,20] arsenic, [18] and seleniu...

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Effect of Pore Structure on the Nitridation of Mesoporous Silica with Ammonia

Cited by 20 publications

References 44 publications

Conversion of Ethanol into Polyolefin Building Blocks: Reaction Pathways on Nickel Ion‐loaded Mesoporous Silica

Conversion of Ethanol into Polyolefin Building Blocks: Reaction Pathways on Nickel Ion‐loaded Mesoporous Silica

Preparation of porous MTiO (M = Cr, Mo, or W) composite oxides from a mesostructured material of titanium oxysulfate and surfactant micelles based on a wall ion exchange–calcination method

Preparation of Porous ZrO₂‐Based Composite Oxides Containing W, Cr, Mo, or V Through a Wall Ion‐Exchange Method

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Effect of Pore Structure on the Nitridation of Mesoporous Silica with Ammonia

Cited by 20 publications

References 44 publications

Conversion of Ethanol into Polyolefin Building Blocks: Reaction Pathways on Nickel Ion‐loaded Mesoporous Silica

Conversion of Ethanol into Polyolefin Building Blocks: Reaction Pathways on Nickel Ion‐loaded Mesoporous Silica

Preparation of porous MTiO (M = Cr, Mo, or W) composite oxides from a mesostructured material of titanium oxysulfate and surfactant micelles based on a wall ion exchange–calcination method

Preparation of Porous ZrO2‐Based Composite Oxides Containing W, Cr, Mo, or V Through a Wall Ion‐Exchange Method

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Preparation of Porous ZrO₂‐Based Composite Oxides Containing W, Cr, Mo, or V Through a Wall Ion‐Exchange Method