Non-hydrolytic sol–gel routes to heterogeneous catalysts

Replacing fossil fuels with biodiesel enables the emission of greenhouse gases to be decreased and reduces dependence on fossil fuels in countries with poor natural resources. Biodiesel can be produced by an esterification reaction between free fatty acids (FFAs) and methanol or by transesterification of triglycerides from oils. Both reactions require homogeneous or heterogeneous catalysis. Production of biodiesel catalyzed by heterogeneous catalysts seems to be the preferred route, enabling easy product separation. As we have previously shown, the Lewis acids AlCl3 and BF3 can serve as highly efficient catalysts under ultrasonic activation. The present study focused on the development of oleic acid (OA) esterification with methanol by the same catalysts immobilized in silica matrices using the sol–gel synthesis route. During the course of immobilization, AlCl3 converts to AlCl3 × 6H2O (aluminite) and BF3 is hydrolyzed with the production of B2O3. The immobilized catalysts can be reused or involved in a continuous process. The possibility of biodiesel production using immobilized catalysts under ultrasonic activation is shown for the conversion of FFAs into biodiesel in batch and continuous mode.

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Fabrication of Core-Shell Structural SiO2@H3[PM12O40] Material and Its Catalytic Activity

Journal of Nanomaterials ◽

10.1155/2014/835931 ◽

2014 ◽

Vol 2014 ◽

pp. 1-8

Author(s):

Xin Yang ◽

Junhai Wang ◽

Qi Zhang ◽

Xu Wang ◽

Linlin Xu ◽

...

Keyword(s):

Catalytic Activity ◽

Heterogeneous Catalysts ◽

Sol Gel ◽

Operating Conditions ◽

Core Shell ◽

Catalytic Wet Air Oxidation ◽

Air Oxidation ◽

Wet Air Oxidation ◽

Heterogeneous Catalytic ◽

Room Condition

Through a natural tree grain template and sol-gel technology, the heterogeneous catalytic materials based on polyoxometalate compounds H3[PM12O40] encapsulating SiO2: SiO2@H3[PM12O40] (SiO2@PM12, M = W, Mo) with core-shell structure had been prepared. The structure and morphology of the core-shell microspheres were characterized by the XRD, IR spectroscopy, UV-Vis absorbance, and SEM. These microsphere materials can be used as heterogeneous catalysts with high activity and stability for catalytic wet air oxidation of pollutant dyes safranine T (ST) at room condition. The results show that the catalysts have excellent catalytic activity in treatment of wastewater containing 10 mg/L ST, and 94% of color can be removed within 60 min. Under different cycling runs, it is shown that the catalysts are stable under such operating conditions and the leaching tests show negligible leaching effect owing to the lesser dissolution.

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Sol–gel synthesis of heterogeneous catalysts from aqueous solutions

Catalysis Today ◽

10.1016/s0920-5861(98)00034-0 ◽

1998 ◽

Vol 41 (1-3) ◽

pp. 3-19 ◽

Cited By ~ 98

Author(s):

J Livage

Keyword(s):

Aqueous Solutions ◽

Heterogeneous Catalysts ◽

Sol Gel ◽

Sol Gel Synthesis

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Catalytic Materials by Design from Hybrid Organic-Inorganics

MRS Proceedings ◽

10.1557/proc-519-41 ◽

1998 ◽

Vol 519 ◽

Cited By ~ 3

Author(s):

Joël ◽

J.E. Moreau ◽

Michel Wong Chi Man

Keyword(s):

Heterogeneous Catalysts ◽

Sol Gel ◽

Inorganic Materials ◽

Hybrid Network ◽

Intrinsic Properties ◽

Reaction Conditions ◽

Molecular Precursors ◽

Catalytic Materials ◽

Materials By Design ◽

Gel Processing

AbstractThe sol-gel processing of appropriated molecular precursors easily leads to a variety of hybrid organic-inorganic materials with intrinsic properties. This approach is increasingly becoming an interesting way to prepare heterogeneous catalysts. The paper will focus on the use of hybrids for the preparation of selective catalytic materials. Two examples of the use of hybrid polysilsesquioxanes polymers will be given. i) The tailoring of the pore structure of silicas, under mild reaction conditions, based on the temporary introduction of different organic substructures in the hybrid network of polysilsesquioxane gels will be discussed. ii) Also the preparation of new chiral hybrid supports for enantioselective catalysis will be presented.

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ChemInform Abstract: Sol-Gel Derived Hybrid Materials as Heterogeneous Catalysts for the Synthesis of N,N-Dimethylformamide from Supercritical Carbon Dioxide

ChemInform ◽

10.1002/chin.199645211 ◽

2010 ◽

Vol 27 (45) ◽

pp. no-no

Author(s):

O. KROECHER ◽

R. A. KOEPPEL ◽

A. BAIKER

Keyword(s):

Carbon Dioxide ◽

Supercritical Carbon Dioxide ◽

Hybrid Materials ◽

Heterogeneous Catalysts ◽

Sol Gel ◽

Supercritical Carbon

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Towards the Rational Design of Supported-Bimetallic Nanoparticle Catalysts

MRS Proceedings ◽

10.1557/proc-1217-y01-07 ◽

2009 ◽

Vol 1217 ◽

Author(s):

Priyabrat Dash ◽

Robert W. J. Scott

Keyword(s):

Rational Design ◽

Heterogeneous Catalysts ◽

Sol Gel ◽

Size Composition ◽

Large Degree ◽

Thermal Reduction ◽

Nanoparticle Catalysts ◽

Calcination Temperatures ◽

Oxide Support ◽

Compositional Uniformity

AbstractHeterogeneous catalysts consisting of nanoparticles dispersed on an oxide support are a mainstay in industrial reactions, and are often made via thermal reduction of metal salts dispersed onto a pre-synthesized support. Herein we document a route towards the design of xerogel-supported nanoparticle catalysts by trapping compositionally-tuned polymer-stabilized nanoparticle precursors into sol-gel matrices. Such a route allows in principle for the tuning of the size, composition, architecture, and electronic properties of nanoparticle catalysts, which allows for the development of highly efficient and selective catalysts. As proof of concept we detail the synthesis of co-reduced PdAu nanoparticles in titania supports. The final materials are well-characterized by HRTEM and energy dispersive spectroscopy (EDS), which confirm the compositional uniformity of the nanoparticles. The importance of controlling calcination conditions in order to retain designed nanoparticle compositions is stressed; high temperature calcination conditions lead to a large degree of sintering and loss of compositional uniformity, while mild calcination temperatures can be used to retain nanoparticle compositions and sizes.

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Alkaline niobates ANbO3 (A = Li, Na, K) as heterogeneous catalysts for dipropyl sulfide oxidation

RSC Advances ◽

10.1039/c6ra21749d ◽

2016 ◽

Vol 6 (104) ◽

pp. 102015-102022 ◽

Cited By ~ 5

Author(s):

Candelaria Leal Marchena ◽

Clara Saux ◽

Robinson Dinamarca ◽

Gina Pecchi ◽

Liliana Pierella

Keyword(s):

Selective Oxidation ◽

Heterogeneous Catalysts ◽

Sol Gel ◽

Sulfide Oxidation ◽

Type Structure ◽

Gel Method ◽

Sol Gel Method ◽

Perovskite Type ◽

Perovskite Type Structure

Alkaline ANbO3 (A = Li, Na, K) niobates with perovskite type structure were prepared by sol gel method, extensively characterized and evaluated as heterogeneous catalysts for selective oxidation of dipropyl sulfide to its corresponding sulfoxide.

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