Preparation and pore structure stability at high temperature of silicon-doped ordered mesoporous alumina

Zhao, Xiaoliang; Zheng, Ying; Zheng, Yong; Zhan, Yingying; Zheng, Xiaowei

doi:10.1039/c3ra47872f

Cited by 22 publications

(11 citation statements)

References 48 publications

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“…The solid-acid component of alumina for the preparation of hybrid catalysts has been more generally used than zeolites because it shows a higher selectivity to DME due to its lower amount of strong acidic sites, which can possibly produce hydrocarbon byproducts by the reforming reaction of DME and (or) methanol at an uncontrolled high reaction temperature in an adiabatic condition [10,11]. In addition, the easily tunable pore size, surface area, and acid sites of alumina have been more attractive for preparing hybrid catalysts by incorporating copper-based hydrogenation catalysts [12,13].…”

Section: Introductionmentioning

confidence: 99%

The role of the acidity of alumina prepared by aluminum-carbon black composite for CO hydrogenation to dimethyl ether on hybrid Cu–ZnO–Al2O3/alumina

Ham

Jeong

Koo

et al. 2015

Reac Kinet Mech Cat

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The effects of surface area and the acidity of mesoporous c-Al 2 O 3 , which is prepared by calcining aluminum-carbon black composite (Al/CB) of the precipitated aluminum nitrate on carbon black at different weight ratios, were investigated to verify the roles of carbon black in the surface properties and stability of Cu-ZnO-Al 2 O 3 for the direct synthesis of dimethyl ether (DME) from syngas. A high surface area of *100 m 2 /g with a large pore diameter of *25 nm originated from the occupied spaces of carbon black enhanced the dispersion of the active Cu-ZnO-Al 2 O 3 particles by forming a strong and stable interaction with mesoporous solid acid c-Al 2 O 3 surfaces. The enhanced dispersion of copper-containing particles, being strongly interacted with the acid sites of the hybrid Cu-ZnO-Al 2 O 3 / Al 2 O 3 catalyst using c-Al 2 O 3 prepared at an optimal Al/CB weight ratio of 10, is mainly responsible for the high CO conversion with a high yield to oxygenates and a suppressed aggregation of active copper species during the direct synthesis of DME from syngas.Keywords Dimethyl ether (DME) Á Syngas Á Cu-ZnO-Al 2 O 3 Á Hybrid catalyst Á Composite of carbon black and alumina Á Acid sites Electronic supplementary material The online version of this article (

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Section: Introductionmentioning

confidence: 99%

The role of the acidity of alumina prepared by aluminum-carbon black composite for CO hydrogenation to dimethyl ether on hybrid Cu–ZnO–Al2O3/alumina

Ham

Jeong

Koo

et al. 2015

Reac Kinet Mech Cat

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“…The synthesis of samples assisted with carboxylic acids was followed the typical procedure [10]. The molar ratio of Al 3 þ :Si 4 þ : Pluronic P123:carboxylic acid in the final solution was fixed at 1:0.07:0.017:0.15 and the exact content of the dopant Si was 6.87% determined by a PANalytical Axios XRF Petro spectrometer.…”

Section: Methodsmentioning

confidence: 99%

“…Subsequently, our group extended this approach to obtain a series of thermally stable OMA by using different carboxylic acids as interfacial protectors, such as a mixture of salicylic acid and citric acid [7], o-phthalic acid [8] and p-aminobenzoic acid [9], which exhibited large surface area in range of 200-300 m 2 g À 1 after calcined at 800°C. Recently, we introduced silicon as a dopant to further stabilize the structure of OMAs in the presence of HCl [10].…”

Section: Introductionmentioning

confidence: 99%

Carboxylic acid assisted synthesis of ordered mesoporous silicon-doped γ-alumina with high thermal stability

et al. 2015

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“…For instance, Ni, Mg, Fe, Cr, Cu, Ce, La, Y, Ca and Sn were successfully supported on OMA. 35,36 Si-, Ce-, and Zr-doped OMA, 37 Ce-Zr-Co-doped OMA, 38,39 Cu/Ce-OMA, 40 La-doped OMA 41 and noble metal-doped OMA (Pt, Ag and Pd) 42 were also prepared. Similarly, OMA-supported metal oxides such as MgO, CaO, TiO 2 , and Cr 2 O 3 35 and ordered titania-alumina mixed oxides 43 were also obtained.…”

Section: Introductionmentioning

confidence: 99%

Synthesis, characterization and insights into stable and well organized hexagonal mesoporous zinc-doped alumina as promising metathesis catalysts carrier

2015

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A series of highly ordered hexagonal mesoporous alumina and zinc-modified mesoporous alumina samples are synthesized via a sol-gel method through an evaporation-induced self-assembly process using Pluronic F127 as nonionic templating agent and several aluminum precursors. The process was mediated using several carboxylic acids along with hydrochloric acid in ethanol. Successful impregnation of ZnCl2 was achieved while maintaining the ordered structure. The surface and textural properties of the materials were investigated. N2-physisorption analysis revealed a BET surface area of 394 m(2) g(-1) and a pore volume around 0.55 cm(3) g(-1). Moreover, small-angle XRD diffraction patterns highlighted the well-organized hexagonal structure even upon the incorporation of zinc chloride. The organized-structure arrangement was further confirmed by transmission electron microscopy (TEM) analysis. The Zn/Al composition of the final materials was confirmed by EDX and XPS analysis, and the zinc amount incorporated was analyzed by ICP. Furthermore, the surface modification with zinc chloride impregnation was analyzed by XPS, (1)H and (27)Al MAS-NMR and FTIR spectroscopic techniques. In addition, the effects of synthesis conditions and the mechanism of the mesostructure formation were explored. The catalytic activity of several methyltrioxorhenium (MTO)-based catalysts supported on these hexagonal mesoporous alumina materials was tested for methyl oleate self-metathesis. The results showed improved kinetics using hexagonal alumina in comparison to those using wormhole-like alumina counterparts. This behavior could be attributed to better mass transfer features of hexagonal mesoporous alumina. The prepared materials with desirable pore size and structure are suitable candidates as catalyst supports for metathesis of bulky functionalized olefins and other catalytic transformations due to their enhanced Lewis acidity and more uniform pore networks favoring enhanced and selective mass transfer phenomena.

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Preparation and pore structure stability at high temperature of silicon-doped ordered mesoporous alumina

Abstract: Ordered mesoporous γ-Al2O3 with high thermal stability and low-level residual chlorine is obtained by optimizing sol–gel parameters and silicon content.

Cited by 22 publications

References 48 publications

The role of the acidity of alumina prepared by aluminum-carbon black composite for CO hydrogenation to dimethyl ether on hybrid Cu–ZnO–Al2O3/alumina

The role of the acidity of alumina prepared by aluminum-carbon black composite for CO hydrogenation to dimethyl ether on hybrid Cu–ZnO–Al2O3/alumina

Carboxylic acid assisted synthesis of ordered mesoporous silicon-doped γ-alumina with high thermal stability

Synthesis, characterization and insights into stable and well organized hexagonal mesoporous zinc-doped alumina as promising metathesis catalysts carrier

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