Mesoporous alumina infiltrated with a very thin and complete carbon layer

Il'inich, G.N.; Kvon, Ren I.; Ayupov, Artem B.; Чумаченко, В. А.; Романенко, А. С.

doi:10.1016/j.micromeso.2015.01.042

Cited by 4 publications

(5 citation statements)

References 28 publications

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“…The carbon phase formed by CVD is therefore either nonporous or more uniformly deposited on the surface of the alumina, thus limiting the formation of carbon-rich zones or aggregates. The second hypothesis is preferred because it is in agreement with the results of Ilinich et al regarding C/alumina composites formed by ethylene carbonization . The average pore diameter decreases much more rapidly with the carbon content than for samples prepared by impregnation/pyrolysis (Table and Figures S11 and S14, Supporting Information).…”

Section: Resultssupporting

confidence: 91%

“…The second hypothesis is preferred because it is in agreement with the results of Ilinich et al regarding C/alumina composites formed by ethylene carbonization. 36 The average pore diameter decreases much more rapidly with the carbon content than for samples prepared by impregnation/pyrolysis (Table 5 and Figures S11 and S14, Supporting Information). This difference reinforces the hypothesis of a less homogeneous covering in the case of composites prepared by impregnation.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

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Selective Carbon Deposition on γ-Alumina Acid Sites: toward the Design of Catalyst Supports with Improved Hydrothermal Stability in Aqueous Media

Girel

Cabiac

Chaumonnot

et al. 2020

ACS Appl. Mater. Interfaces

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γ-alumina, a widely used industrial catalyst support, undergoes irreversible transformation into various aluminum hydroxides under hydrothermal conditions, resulting in strong modification of its intrinsic properties. Most of the strategies that have been proposed to prevent or at least minimize its transformation into oxy-hydroxides consist in covering the alumina surface by a hydrophobic carbon layer, making it less sensitive to modifications induced by water. However, such methods necessitate high carbon contents, which significantly modifies structural and chemical properties of alumina. Here, we propose a new method based on a series of adsorption/pyrolysis cycles using sorbitol molecules previously adsorbed on specific hydration sites of (110) faces of γ-alumina crystals. Those sites, which are responsible for the dissolution f γ-alumina crystals in water, are thus selectively protected by carbon clusters, the rest of the surface being totally exposed and accessible to adsorbates. Under hydrothermal conditions (10 hours in water at 200°C), the formation of hydroxides is almost totally suppressed by covering less than 25% of the surface with only 7 wt. % carbon, which is far below the amount necessary to get similar results with more conventional carbon deposition methods.

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Section: Resultssupporting

confidence: 91%

Section: ■ Results and Discussionmentioning

confidence: 99%

Selective Carbon Deposition on γ-Alumina Acid Sites: toward the Design of Catalyst Supports with Improved Hydrothermal Stability in Aqueous Media

Girel

Cabiac

Chaumonnot

et al. 2020

ACS Appl. Mater. Interfaces

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“…In addition, FTIR spectra showed that Pdop covers the surface of Al 2 O 3 blocking surface OH groups, consequently, forming an adlayer between the support and the metal precursors. Note that in contrast to other preparation methods of carbon‐coated alumina,, the Pdop layer hardly reduces the porosity of the Al 2 O 3 support (Figure S11). When Mo precursors are added to Pdop coated Al 2 O 3 , the catechol groups present in Pdop complexes with Mo ions .…”

Section: Resultsmentioning

confidence: 89%

“…As a result, more Co atoms are available to promote the MoS 2 crystallites formed during sulfidation. Coating the surface of alumina with carbon is another suitable option . Weakening the interaction with the support avoids the formation of catalytically inactive refractory species like CoAl 2 O 4 and Al(OH) 6 Mo 6 O 18 , but may also decrease the dispersion of the active phase.…”

Section: Introductionmentioning

confidence: 99%

Efficient CoMoS Catalysts Supported on Bio‐Inspired Polymer Coated Alumina for Hydrotreating Reactions

et al. 2017

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Organic additives are widely used in order to improve the performance of hydrotreating catalysts. Yet, the use of polymers, in particular bio‐polymers, is less widespread. We present, herein, a strategy to coat alumina support with a bio‐polymer, namely polydopamine (Pdop). The Pdop coated supports provide a higher number of adsorption sites for Mo species compared to the bare support. The hydrotreating catalyst prepared on Pdop coated support showed improved performances for various hydrotreating reactions (aromatic hydrogenation, gas‐oil HDS and HDN). The increase in activity is ascribed to a better accessibility of active sites, and the presence of carbon adlayer between the active phase and alumina limiting detrimental direct metal support interactions. Modification of the alumina surfaces by Pdop creates new adsorption sites for metallic precursors, thereby allowing an improved accessibility of active sites especially at high surface densities.

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“…Ilinich et al [24] investigated mesoporous carbon infiltrated Al 2 O 3 with a relatively thin carbon coating. The obtained product had high electrical conductivity and resistance to acidic media.…”

Section: Introductionmentioning

confidence: 99%

Pyrocarbon Coating on Granular Al2O3 for HTGR-Type Power Reactor

Sklabinskyi,

Pitel,

Skydanenko

et al. 2023

Coatings

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Fourth-generation nuclear power systems are based on high-temperature gas-cooled reactors, in which the pebble fuel is the primary energy carrier. In this regard, applying protective pyrocarbon coatings on granulated fuel is an essential problem in ensuring the reliability of nuclear power plants. The article’s main idea is to research rational technological parameters of forming a pyrocarbon protective coating on the granules of a nuclear fuel model. For this purpose, granulated Al2O3 with the protective pyrocarbone coating was applied as a fuel model. The article’s aim is to study the effect of thermophysical parameters on applying a protective pyrocarbon coating on granulated Al2O3. During the experimental studies, thermal imaging of the pyrolysis process was used. The scientific novelty of the work is the equilibrium curves for the systems Al2O3:CH4, Al2O3:CH4:N2, and Al2O3:CH4:Ar. Their analysis allowed for evaluating rational thermochemical parameters of the pyrolysis process. As a result, rational thermophysical parameters of coating granulated Al2O3 with a pyrocarbon layer were evaluated, and the practical possibility of applying the pyrocarbon coating to granulated Al2O3 in the electrothermal fluidized bed was experimentally proven. It was shown that nitrogen does not significantly affect the target reaction product under a temperature of less than 1500 K. Also, the rational conditions for the pyrocarbon coating at a pressure of 0.1 MPa were realized at a temperature of 900–1500 K and using argon. Moreover, pyrocarbon was precipitated from hydrocarbon at 1073–1273 K. Overall, the need to add an inert gas for reducing the carbon black formation was proven to prevent a reduction of natural gas efficiency.

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Mesoporous alumina infiltrated with a very thin and complete carbon layer

Cited by 4 publications

References 28 publications

Selective Carbon Deposition on γ-Alumina Acid Sites: toward the Design of Catalyst Supports with Improved Hydrothermal Stability in Aqueous Media

Selective Carbon Deposition on γ-Alumina Acid Sites: toward the Design of Catalyst Supports with Improved Hydrothermal Stability in Aqueous Media

Efficient CoMoS Catalysts Supported on Bio‐Inspired Polymer Coated Alumina for Hydrotreating Reactions

Pyrocarbon Coating on Granular Al2O3 for HTGR-Type Power Reactor

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