scholarly journals Mesoporous carbon and microporous zeolite supported Ru catalysts for selective levulinic acid hydrogenation into γ-valerolactone

2019 ◽  
Vol 6 (1) ◽  
pp. 38-50 ◽  
Author(s):  
I.L. Simakova ◽  
Yu.S. Demidova ◽  
M.N. Simonov ◽  
P.S. Niphadkar ◽  
V.V. Bokade ◽  
...  
Keyword(s):  
Mesoporous Carbon ◽  
Levulinic Acid ◽  
Supported Catalysts ◽  
Sol Gel ◽  
Chemical Properties ◽  
National Chemical Laboratory ◽  
Chemical Laboratory ◽  
Catalyst Screening ◽  
Method Optimization ◽  
Microporous Zeolite

Abstract Ru supported on mesoporous carbon Sibunit and microporous zeolites (HZSM-5, SiO2/Al2O3 = 250; H-Beta, SiO2/Al2O3 = 30; H-Y, SiO2/Al2O3 = 5; H-USY, SiO2/Al2O3 = 30) synthesized by the sol-gel method (CSIR-National Chemical Laboratory, Pune India) were prepared by impregnation of the corresponding supports with RuCl3∙nH2O (0.1 M) followed by reduction in H2. Catalyst screening in levulinic acid (LA) (15 mL, 6.9 mmol) hydrogenation into g-valerolactone (GVL) with 1,4-dioxane (165°C, hydrogen pressure ca. 16 bar) as a solvent showed higher activity and selectivity to GVL of Ru/zeolites compared to carbon supported catalysts. Among Ru/zeolites LA conversion increased as follows Ru/HZSM-5 < Ru/H-Y < Ru/H-USY < Ru/H-Beta demonstrating a clear advantage of H-Beta preparation method. Optimization of the support microstructure and acidity opens a reliable way for selective catalytic LA hydrogenation to GVL. The catalysts were analyzed by TEM, XRD, H2-TPR and N2 physisorption to compare their physical chemical properties.

scholarly journals Carbon Supported Size-Controlled Ru Catalysts for Selective Levulinic Acid Hydrogenation into γ-Valerolactone

2020 ◽  
pp. 5-16 ◽  
Author(s):  
Irina L. Simakova ◽  
Yuliya S. Demidova ◽  
Mikhail N. Simonov ◽  
Prashant S. Niphadkar ◽  
Vijay V. Bokade ◽  
...  
Keyword(s):  
Particle Size ◽  
Liquid Phase ◽  
Mesoporous Carbon ◽  
Levulinic Acid ◽  
Chemical Properties ◽  
Monometallic Catalysts ◽  
Ru Nanoparticles ◽  
Physical Chemical ◽  
Mesoporous Carbon Material ◽  
Size Controlled

Liquid phase levulinic acid hydrogenation into γ-valerolactone in 1,4-dioxane as a solvent (165°C, 20 bar) was studied over a range of Ru monometallic catalysts using mesoporous carbon material Sibunit as a support. In addition to the catalyst prepared by impregnation with RuCl3∙nH2O (0.1 M) followed by reduction in H2, size-controlled Ru(NPs)/Sibunit catalysts were synthesized by immobilization of polyvinylpyrrolidone (PVP) stabilized Ru nanoparticles (NPs) (dRu=2.4 nm). Сarbon supported colloidal Ru NPs were not studied earlier in levulinic acid hydrogenation. Activity of colloidal Ru(NPs)/Sibunit catalysts was found to be lower than that of impregnated Ru/Sibunit which could be attributed to hampering effect of PVP. However, colloidal Ru(NPs)/Sibunit purified by thermal treatment in air (180°C) followed by reduction in H2 (400°C) exhibited the same activity as impregnated one yielding 93% γ-valerolactone at 100% levulinic acid conversion. Applicability of supported PVP-assisted colloidal Ru NPs in hydrogenation of levulinic acid illustrates a potential to prepare more efficient catalysts for this reaction with a desired particle size. The catalysts were characterized by TEM, XRF, and N2 physisorption to compare their physical chemical properties

scholarly journals Colloidal Characteristics of Molybdenum Blue Nanoparticles Dispersion for Catalytic Applications

2020 ◽  
Vol 4 (1) ◽  
pp. 24
Author(s):  
Natalia Gavrilova ◽  
Maria Myachina ◽  
Ksenia Poluboyarinova ◽  
Ekaterina Novaeva ◽  
Victor Nazarov
Keyword(s):  
Supported Catalysts ◽  
Sol Gel ◽  
Chemical Properties ◽  
Aggregate Stability ◽  
Surface Characteristics ◽  
Aggregative Stability ◽  
Dispersed Phase ◽  
High Concentration ◽  
Molybdenum Blue ◽  
Wide Range

The nanosized clusters of molybdenum blues and their monodispersity make them possible to consider as promising precursors for molybdenum carbide preparation. For the synthesis of supported catalysts using sols (dispersions of nanoparticles), it is necessary to know their main colloidal-chemical properties (electro-surface characteristics, rheological properties and the conditions of aggregative stability). This paper presents the results of a study of the colloidal-chemical properties of molybdenum blue, the dispersed phase of which is represented by toroidal particles of the Mo154-x family. It was found that aggregate stable sols exist in the range of 0.8 ˂ pH ˂ 2.0. In this range, molybdenum blue particles are negatively charged, and the electrokinetic potential does not exceed 30 mV. Molybdenum blues have high aggregate stability and can be concentrated to a high concentration of the dispersed phase (20–30 wt%); at a concentration more than 30 wt.%, a transition of the sol into a gel is observed. In a wide range of concentrations, molybdenum blues are Newtonian liquids, and the viscosity mainly depends on the concentration of the dispersed phase. The results obtained can be used as a basis for the development of a sol–gel method of supported catalysts based on molybdenum blue.

Cu Doped TiO2: Visible Light Assisted Photocatalytic Antimicrobial Activity and High Temperature Anatase Stability

2018 ◽  
Author(s):  
Snehamol Mathew ◽  
Priyanka Ganguly ◽  
Stephen Rhatigan ◽  
Vignesh Kumaravel ◽  
Ciara Byrne ◽  
...  
Keyword(s):  
Visible Light ◽  
Visible Light Irradiation ◽  
Density Functional ◽  
Anatase Phase ◽  
Sol Gel ◽  
Chemical Properties ◽  
Light Irradiation ◽  
Health Concern ◽  
Bacterial Inactivation ◽  
X Ray

Indoor surface contamination by microbes is a major public health concern. A damp environment is one potential sources for microbe proliferation. Smart photocatalytic coatings on building surfaces using semiconductors like titania (TiO<sub>2</sub>) can effectively curb this growing threat.<b> </b>Metal-doped titania in anatase phase has been proved as a promising candidate for energy and environmental applications. In this present work, the antimicrobial efficacy of copper (Cu) doped TiO<sub>2 </sub>(Cu-TiO<sub>2</sub>) was evaluated against <i>Escherichia coli</i> (Gram-negative) and <i>Staphylococcus aureus</i> (Gram-positive) under visible light irradiation. Doping of a minute fraction of Cu (0.5 mol %) in TiO<sub>2 </sub>was carried out <i>via</i> sol-gel technique. Cu-TiO<sub>2</sub> further calcined at various temperatures (in the range of 500 °C – 700 °C) to evaluate the thermal stability of TiO<sub>2</sub> anatase phase. The physico-chemical properties of the samples were characterised through X-ray diffraction (XRD), Raman spectroscopy, X-ray photo-electron spectroscopy (XPS) and UV-visible spectroscopy techniques. XRD results revealed that the anatase phase of TiO<sub>2</sub> was maintained well, up to 650 °C, by the Cu dopant. UV-DRS results suggested that the visible light absorption property of Cu-TiO<sub>2 </sub>was enhanced and the band gap is reduced to 2.8 eV. Density functional theory (DFT) studies emphasises the introduction of Cu<sup>+</sup> and Cu<sup>2+</sup> ions by replacing Ti<sup>4+</sup> ions in the TiO<sub>2</sub> lattice, creating oxygen vacancies. These further promoted the photocatalytic efficiency. A significantly high bacterial inactivation (99.9%) was attained in 30 mins of visible light irradiation by Cu-TiO<sub>2</sub>.

scholarly journals Green Synthesis of N/Zr Co-Doped TiO2 for Photocatalytic Degradation of p-Nitrophenol in Wastewater

Catalysts ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 235
Author(s):  
Hayette Benkhennouche-Bouchene ◽  
Julien G. Mahy ◽  
Cédric Wolfs ◽  
Bénédicte Vertruyen ◽  
Dirk Poelman ◽  
...  
Keyword(s):  
Visible Light ◽  
Tio2 Nanoparticles ◽  
Sol Gel ◽  
Visible Region ◽  
Chemical Properties ◽  
Pure Tio2 ◽  
Molar Ratio ◽  
Xps Spectra ◽  
Doped Tio2 ◽  
Co Doped

TiO2 prepared by a green aqueous sol–gel peptization process is co-doped with nitrogen and zirconium to improve and extend its photoactivity to the visible region. Two nitrogen precursors are used: urea and triethylamine; zirconium (IV) tert-butoxide is added as a source of zirconia. The N/Ti molar ratio is fixed regardless of the chosen nitrogen precursor while the quantity of zirconia is set to 0.7, 1.4, 2, or 2.8 mol%. The performance and physico-chemical properties of these materials are compared with the commercial Evonik P25 photocatalyst. For all doped and co-doped samples, TiO2 nanoparticles of 4 to 8 nm of size are formed of anatase-brookite phases, with a specific surface area between 125 and 280 m2 g−1 vs. 50 m2 g−1 for the commercial P25 photocatalyst. X-ray photoelectron (XPS) measurements show that nitrogen is incorporated into the TiO2 materials through Ti-O-N bonds allowing light absorption in the visible region. The XPS spectra of the Zr-(co)doped powders show the presence of TiO2-ZrO2 mixed oxide materials. Under visible light, the best co-doped sample gives a degradation of p-nitrophenol (PNP) equal to 70% instead of 25% with pure TiO2 and 10% with P25 under the same conditions. Similarly, the photocatalytic activity improved under UV/visible reaching 95% with the best sample compared to 50% with pure TiO2. This study suggests that N/Zr co-doped TiO2 nanoparticles can be produced in a safe and energy-efficient way while being markedly more active than state-of-the-art photocatalytic materials under visible light.

scholarly journals The Influence Of NO/O2 On The NOx Storage Properties Over A Pt-Ba-Ce/γ-Al2O3 Catalyst

2019 ◽  
Vol 17 (1) ◽  
pp. 1459-1465
Author(s):  
Xuedong Feng ◽  
Jing Yi ◽  
Peng Luo
Keyword(s):  
Sol Gel ◽  
Chemical Properties ◽  
No Oxidation ◽  
Test Results ◽  
X Ray Diffraction ◽  
Storage Performance ◽  
Transmission Electron ◽  
Temperature Programmed ◽  
Physical And Chemical ◽  
Al2o3 Catalyst

AbstractWith the purpose of studying the influence of NO/O2 on the NOx storage activity, a Pt-Ba-Ce/γ-Al2O3 catalyst was synthesized by an acid-aided sol-gel method. The physical and chemical properties of the catalyst were characterized by X-ray diffraction (XRD) and Transmission Electron Microscope (TEM) methods. The results showed that the composition of the catalyst was well-crystallized and the crystalline size of CeO2 (111) was about 5.7 nm. The mechanism of NO and NO2 storage and NOx temperature programmed desorption (NO-TPD) experiments were investigated to evaluate the NOx storage capacity of the catalyst. Pt-Ba-Ce/γ-Al2O3 catalyst presented the supreme NOx storage performance at 350℃, and the maximum value reached to 668.8 μmol / gcat. Compared with O2-free condition, NO oxidation to NO2 by O2 had a beneficial effect on the storage performance of NOx. NO-TPD test results showed that the NOx species stored on the catalyst surface still kept relatively stable even below 350℃.

Silver Nanoparticles Supported on Ordered Mesoporous Carbon for Formaldehyde Electrooxidation

2011 ◽  
Vol 110-116 ◽  
pp. 508-513
Author(s):  
Ling Bin Kong ◽  
Ru Tao Wang ◽  
Xiao Wei Wang ◽  
Zhen Sheng Yang ◽  
Yong Chun Luo ◽  
...  
Keyword(s):  
Fuel Cells ◽  
Mesoporous Carbon ◽  
Chemical Reduction ◽  
Chemical Properties ◽  
Ordered Mesoporous Carbon ◽  
Alkaline Solutions ◽  
Cyclic Voltammograms ◽  
Peak Current Density ◽  
Ordered Mesoporous ◽  
Physical And Chemical

Metal nanocatalysts, as the anodic materials, have become increasingly important in fuel cells due to their unique physical and chemical properties. Here we report the ordered mesoporous carbon (CMK-3) supported silver nanocatalysts have been prepared through the wet chemical reduction by using the reduction of formaldehyde. The electrochemical properties of the Ag/CMK-3 nanocatalysts for formaldehyde oxidation are studied by cyclic voltammograms (CV) and chronoamperometric curves (i-t) in alkaline aqueous solutions. The results show that the peak current density (from CV) of the Ag/CMK-3 electrode is 112 mA cm-2, above 2 times higher than that of Ag/XC-72 at the same Ag loading (14.15 μg cm-2). Furthermore, the i-t curves demonstrate that the Ag/CMK-3 nanocatalysts are efficient and stable electrocatalysts for anodic oxidation of formaldehyde in alkaline solutions. Our results indicate that the application potential of Ag/CMK-3 nanocatalysts with the improved electrocatalytic activity has far reaching effects on fuel cells and sensors.

Preparation and Photocatalytic Activity of Mixed Phase Anatase/rutile TiO2 Nanoparticles for Phenol Degradation

2014 ◽  
Vol 70 (2) ◽  
Author(s):  
Mohamad Azuwa Mohamed ◽  
Wan Norharyati Wan Salleh ◽  
Juhana Jaafar ◽  
Norhaniza Yusof
Keyword(s):  
Photocatalytic Activity ◽  
Tio2 Nanoparticles ◽  
High Performance ◽  
Sol Gel ◽  
Phenol Degradation ◽  
Chemical Properties ◽  
Mixed Phase ◽  
Rutile Tio2 ◽  
Physico Chemical ◽  
Degussa P25

The evolution of desirable physico-chemical properties in high performance photocatalyst materials involves steps that must be carefully designed, controlled, and optimized. This study investigated the role of key parameter in the preparation and photocatalytic activity analysis of the mixed phase of anatase/rutile TiO2 nanoparticles, prepared via sol-gel method containing titanium-n-butoxide Ti(OBu)4 as a precursor material, nitric acid as catalyst, and isopropanol as solvent. The prepared TiO2 nanoparticles were characterized by means of XRD, SEM, and BET analyses, and UV-Vis-NIR spectroscopy. The results indicated that the calcination temperature play an important role in the physico-chemical properties and photocatalytic activity of the resulting TiO2 nanoparticles. Different calcination temperatures would result in different composition of anatase and rutile. The photocatalytic activity of the prepared mixed phase of anatase/rutile TiO2 nanoparticles was measured by photodegradation of 50 ppm phenol in an aqueous solution. The commercial anatase from Sigma-Aldrich and Degussa P25 were used for comparison purpose. The mixed phase of anatase/rutile TiO2 nanoparticles (consists of 38.3% anatase and 61.7% rutile) that was prepared at 400°C exhibited the highest photocatalytic activity of 84.88% degradation of phenol. The result was comparable with photocatalytic activity demonstrated by Degussa P25 by 1.54% difference in phenol degradation. The results also suggested that the mixed phase of anatase/rutile TiO2 nanoparticles is a promising candidate for the phenol degradation process. The high performance of photocatalyst materials may be obtained by adopting a judicious combination of anatase/rutile and optimized calcination conditions.

Structuring-agent role in physical and chemical properties of Mo/SiO2 catalysts by sol-gel method

2018 ◽  
Vol 89 (2) ◽  
pp. 416-425
Author(s):  
William Giovanni Cortés-Ortiz ◽  
Alexander Baena-Novoa ◽  
Carlos Alberto Guerrero-Fajardo
Keyword(s):  
Sol Gel ◽  
Chemical Properties ◽  
Physical And Chemical Properties ◽  
Gel Method ◽  
Sol Gel Method ◽  
Physical And Chemical ◽  
And Chemical Properties
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