scholarly journals PVP-Stabilized Palladium Nanoparticles in Silica as Effective Catalysts for Hydrogenation Reactions

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Caroline Pires Ruas ◽  
Daiane Kessler Fischer ◽  
Marcos Alexandre Gelesky
Keyword(s):  
Catalytic Activity ◽  
Palladium Nanoparticles ◽  
Sol Gel ◽  
Molar Ratio ◽  
Sol Gel Process ◽  
Hydrogenation Reactions ◽  
Acidic Conditions

Palladium nanoparticles stabilized by poly (N-vinyl-2-pyrrolidone) (PVP) can be synthesized by corresponding Pd(acac)2(acac = acetylacetonate) as precursor in methanol at 80°C for 2 h followed by reduction with NaBH4and immobilized onto SiO2prepared by sol-gel process under acidic conditions (HF or HCl). The PVP/Pd molar ratio is set to 6. The effect of the sol-gel catalyst on the silica morphology and texture and on Pd(0) content was investigated. The catalysts prepared (ca.2% Pd(0)/SiO2/HF andca.0,3% Pd(0)/SiO2/HCl) were characterized by TEM, FAAS, and SEM-EDS. Palladium nanoparticles supported in silica with a size 6.6 ± 1.4 nm were obtained. The catalytic activity was tested in hydrogenation of alkenes.

scholarly journals Palladium nanoparticles supported on nitrogen doped porous carbon material derived from cyclodextrin, glucose and melamine based polymer: promising catalysts for hydrogenation reactions

2020 ◽  
Vol 92 (6) ◽  
pp. 827-837 ◽  
Author(s):  
Samahe Sadjadi ◽  
Masoumeh Malmir ◽  
Bastien Léger ◽  
Eric Monflier ◽  
Majid M. Heravi
Keyword(s):  
Catalytic Activity ◽  
Palladium Nanoparticles ◽  
Aqueous Media ◽  
Hydrogenation Reaction ◽  
Molar Ratio ◽  
Porous Carbon Material ◽  
High Catalytic Activity ◽  
Hydrothermal Conditions ◽  
Nitrogen Doped ◽  
Hydrogenation Reactions

AbstractMelamine based polymer (MT) was prepared and then reacted with a mixture of glucose (Glu) and β-cyclodextrin (CD) under hydrothermal conditions to afford, MT/Glu-CD. Then, the adsorption of Pd salt was realized on MT/Glu-CD. The resulting compound was subsequently carbonized to furnish Pd/MT/C that exhibited high catalytic activity for the hydrogenation of nitroarenes in aqueous media. To elucidate the roles of CD, Glu, the molar ratio of Glu:CD and the carbonization in the catalytic activity, several control catalysts have been prepared and their performances for a model hydrogenation reaction were compared with that of Pd/MT/C. The results confirmed the importance of the carbonization as well as the presence of CD for achieving high catalytic activity. Moreover, it was found that the molar ratio of Glu:CD could affect the catalytic activity of the final catalyst and the optimum molar ratio of Glu:CD was 30:70. The recycling test as well as measurement of Pd leaching demonstrated high recyclability and low Pd leaching of Pd/MT/C.

scholarly journals Ionic Liquids/SiO2 Supporting Pd Nanoparticles: Efficient Catalysts in Hydrogenation Reaction

2021 ◽  
pp. 8-12
Author(s):  
Hartz Taís ◽  
Fischer Daiane ◽  
Karina de Fraga ◽  
Scheeren Carla
Keyword(s):  
Ionic Liquids ◽  
Palladium Nanoparticles ◽  
Sol Gel ◽  
Pd Nanoparticles ◽  
Hydrogenation Reaction ◽  
Gel Method ◽  
Sol Gel Method ◽  
Sol Gel Process ◽  
Acidic Conditions ◽  
Palladium Content

Palladium nanoparticles (ca. 4.8 nm) were synthesized in presence of 1-n-butyl-3-methylimidazolium tetraflouroborate (BMI.BF4) and 1-n-butyl-3-methylimidazolium hexafluorophosphate (BMI.PF6) and PMI.Si.(OMe)3.Cl functionalized ionic liquids using the sol-gel method. The characteristics of the sol-gel method, ionic liquid on the palladium content was studied, as well as the silica morphology and texture of the support and the hydrogenation activity. The palladium content in the resulting xerogels (ca. 0.22 wt% Pd/SiO2) was shown to be independent of the sol-gel process. The xerogels synthesized in acidic conditions formed materials with larger pore diameters, which in turn might be responsible for the higher catalytic activity in hydrogenation of the alkenes and arenes obtained with the heterogeneous catalyst (Pd/ILs/SiO2).

Synthesis by sol–gel process, characterization and catalytic activity of vanadia–silica mixed oxides

2005 ◽  
Vol 351 (46-48) ◽  
pp. 3624-3629 ◽  
Author(s):  
Mariza Alves Figueiredo ◽  
André Luiz de Faria ◽  
Marilda das Dores Assis ◽  
Herenilton Paulino Oliveira
Keyword(s):  
Catalytic Activity ◽  
Mixed Oxides ◽  
Sol Gel ◽  
Process Characterization ◽  
Sol Gel Process

Effect of acidity on the properties of silica-aluminas synthesized by sol-gel method

2020 ◽  
Vol 63 (7) ◽  
pp. 126-132
Author(s):  
Lyubov V. Furda ◽  
◽  
Evgenia A. Tarasenko ◽  
Sofya N. Dudina ◽  
Olga E. Lebedeva ◽  
...  
Keyword(s):  
Surface Area ◽  
Sol Gel ◽  
Molar Ratio ◽  
Active Centers ◽  
Indicator Method ◽  
Synthesis Conditions ◽  
Alkaline Conditions ◽  
Acidic Conditions ◽  
Amphoteric Properties ◽  
Hydrolysis Of

In the present work amorphous silica-aluminas were synthesized by the coprecipitation method during the hydrolysis of an alcohol solution of tetraethoxysilane (with a tetraethoxysilane: alcohol mass ratio of 1: 1) and 6% aqueous solution of aluminum nitrate at pH values of 1, 3, and 10. The Si/Al molar ratio for all synthesized samples were 4.72 (± 0.29). The amorphous character of the investigated materials was confirmed by X-ray phase analysis. According to the results of scanning electron microscopy, it was found that the resulting powders have particles with a size of 1-20 μm. It was shown that the conditions of synthesis affected the specific surface area and porosity of the materials under study. By the method of low-temperature adsorption-thermodesorption of nitrogen it was established that silica-aluminas obtained under acidic conditions were microporous materials. For the sample obtained under alkaline conditions (pH = 10), the contribution of macropores is very significant. A decrease in surface area is observed as the pH of the synthesis increases. The Hammett indicator method was used to identify and quantify surface centers of different acidity. All studied silica-aluminas are characterized by the presence of both Brønsted basic (pKax from 7 to 12.8) and acidic (pKax from 0 to 7) centers, and Lewis basic (pKax from -4.4 to 0) with a pronounced maximum at pKax = 1.02. It was found that the synthesis conditions had a significant effect on the concentration of active centers. The values of the Hammett function are practically the same for the 3 studied silica-aluminas and describe the studied samples as materials of medium acidity. The variety of Lewis and Brønsted centers on the surface indicates the amphoteric properties of the materials under study. This gives the samples the properties of polyfunctional sorbents and catalysts.

scholarly journals Interlayer-free Glucose Carbonised Template Silica Membranes for Brine Water Desalination

2019 ◽  
Vol 280 ◽  
pp. 03010 ◽  
Author(s):  
Dwi Rasy Mujiyanti ◽  
Muthia Elma ◽  
Mufidah Amalia
Keyword(s):  
Sol Gel ◽  
Tetraethyl Orthosilicate ◽  
Water Desalination ◽  
Molar Ratio ◽  
Solution Temperature ◽  
Nacl Solution ◽  
Silica Membranes ◽  
Salt Ions ◽  
Sol Gel Process ◽  
Free Glucose

Interlayer-free glucose carbonized template silica membranesbased on tetraethyl orthosilicate (TEOS) and glucose were successfullyprepared using an acid-base catalysed sol-gel method for artificial brinewater desalination (7.5% wt NaCl solution %) at temperatures range from25, 40 and 60 °C. These membranes calcined at 250 and 400 °C. Themembranes were fabricated through sol-gel process by using TEOS(tetraethyl orthosilicate); ethanol; nitric acid; ammonia; aquadest andglucose as a template. By molar ratio is 1: 38: 0.0007: 0.0003: 5 and0.25%; 0.5%, 1% w/v glucose as template. The results show the highestwater fluxes of 1.8, 2.2 and 4.8 kg m−2 h−1 for 25, 40 and 60 °Cdesalination process with excellent salt rejections of 99.5, 99.5 and 99.7%, respectively. It was found that the higher the NaCl solution temperature asfeed solution as well as glucose concentration (0.25% to 1% wt) astemplate attached in the silica matrixes, the higher water fluxes eventhough the salt rejection remain the same. This study demonstrates that theorganosilica membranes offered the carbonized silica mesostructuremembranes with excellent separation of water from the hydrated salt ions, particularly for processing brine salt solutions.

scholarly journals Remarkable catalytic activity of polymeric membranes containing gel-trapped palladium nanoparticles for hydrogenation reactions

2020 ◽  
Author(s):  
Melissa López-Viveros ◽  
Isabelle Favier ◽  
Montserrat Gómez ◽  
Jean-François Lahitte ◽  
Jean-Christophe Remigy
Keyword(s):  
Catalytic Activity ◽  
Palladium Nanoparticles ◽  
Polymeric Membranes ◽  
Hydrogenation Reactions

Immobilization of a Quinonoid Rhodium Catalyst on Silica Gel by the Surface Sol−Gel Process and Catalytic Activity for Phenylacetylene Polymerization

2009 ◽  
Vol 28 (10) ◽  
pp. 3000-3003 ◽  
Author(s):  
Sang Bok Kim ◽  
Chen Cai ◽  
William C. Trenkle ◽  
Dwight A. Sweigart
Keyword(s):  
Catalytic Activity ◽  
Silica Gel ◽  
Sol Gel ◽  
Rhodium Catalyst ◽  
Sol Gel Process

Study on Preparation and Hydrophobicity of MTES Derived Silica Sol and Gel

2012 ◽  
Vol 535-537 ◽  
pp. 2563-2566 ◽  
Author(s):  
Yu Ma ◽  
Hye Ryeon Lee ◽  
Toshinori Tsuru
Keyword(s):  
Reaction Rate ◽  
Sol Gel ◽  
Phase Segregation ◽  
Silica Sol ◽  
Molar Ratio ◽  
Modified Silica ◽  
Sol Gel Process ◽  
One Step ◽  
Inorganic Precursors

The synthesis of hydrophobic sol by one-step sol-gel process ammonia catalyzed was investigated. The water molar ratio and catalyst molar ratio were discussed to prevent phase segregation during the hydrolysis and co-condensation of the organic and inorganic precursors. The reactant system with water molar ratio 70 could make the reaction rate of MTES slightly less than that of TEOS, so that the hydrolysis - condensation – gelling reaction with MTES and TEOS as co-precursors could be synchronously. With the increase of the MTES/TEOS molar ratio, the reaction rate of the silica sol preparation decreased, the hydrophobicity of the sol and gel increased as the molar ratio MTES/TEOS change from 0.5~4. But the hydrophobicity of the methyl-modified silica sol and gel prepared with pure MTES in the sol-gel process were slightly lower than that of the methyl-modified silica sol and gel prepared with MTES and TEOS as co-precursors.

Preparation of Nano-TiO2 Using a Sol-Gel Process Mediated in Reverse Microemulsion Combined with a Solvent Thermal Technique

2011 ◽  
Vol 287-290 ◽  
pp. 1731-1734 ◽  
Author(s):  
Han Sheng Li ◽  
Hang Xu ◽  
Shi Ying Wang ◽  
Ya Lin Pan ◽  
Qin Wu ◽  
...  
Keyword(s):  
Sol Gel ◽  
Average Particle Size ◽  
High Photocatalytic Activity ◽  
Reverse Microemulsion ◽  
Molar Ratio ◽  
Average Particle ◽  
Anatase Structure ◽  
Sol Gel Process ◽  
Triton X ◽  
Thermal Technique

Anatase nano-titania (nano-TiO2) was prepared by using a sol-gel process mediated in reverse microemulsion combined with a solvent thermal technique. The results show that the anatase structure appears in the calcination temperature range of 400-510°C, while the transformation of anatase into rutile takes place above 510°C. The average particle size (dP) of the nano-TiO2 increases with the rise of water/Triton X-100 molar ratio (ω) but decreases with the rise of acetyl acetone/n-TBT molar ratio (p) and n-hexanol/Triton X-100 molar ratio (m). The obtained TiO2 particles with a small size have high photocatalytic activity.

Sign in / Sign up

Export Citation Format

Share Document