Heteropoly Acids Supported on Sol-Gel Matrices and Their Catalytic Activity and Selectivity

1998 ◽  
Vol 549 ◽  
Author(s):  
D.E. Grandstaff ◽  
M. D. Paciolla ◽  
L.T. Sein ◽  
R. Jacob ◽  
K. Narielwala ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Carbon Materials ◽  
Sol Gel ◽  
Catalytic Performance ◽  
Silica Sol ◽  
Heterogeneous Reactions ◽  
Heteropoly Acids ◽  
Oxide Substrates ◽  
Silica Matrices

AbstractHeteropoly acids (HPA) are well known solid acids as well as oxidation catalysts. They find application in both homogeneous and heterogeneous reactions. As catalysts, problems associated with surface area and instability are diminished by supporting the HPA. It has been reported that supporting these materials on oxide substrates or porous carbon materials has resulted in some degree of instability. It has also been shown that encapsulating HPA in sol-gel silica matrices has produced an increase in catalytic performance without compromising the catalytic activity of the HPA. In this work, we analyzed the activity of a silica sol-gel supported HPA catalyst. The reaction which was chosen to illustrate such issues was the oxidation/dehydration of 1-butanol. In addition, the specific role of the support in the catalytic process is described. In this work, we characterized the silica-sol gel supported HPA catalyst to try to understand the effect of preparation in the overall catalytic selectivity and activity.

How does the Support Influence the Catalytic Activity of the Keggin Ion?

1996 ◽  
Vol 454 ◽  
Author(s):  
Zakiyyah Smith ◽  
Michael Palmieri ◽  
Nancy Buecheler ◽  
Susan A. Jansen
Keyword(s):  
Catalytic Activity ◽  
Carbon Materials ◽  
Solid Acid ◽  
Sol Gel ◽  
Catalytic Performance ◽  
Heteropoly Acids ◽  
Keggin Ion ◽  
Oxide Substrates ◽  
Silica Matrices

AbstractHeteropoly acids, HPA are well known solid acid and oxidation catalysts that find application in hetergeneous and homogeneous reactions. In the former, surface area and stability problems are diminshed by supporting the HPA. Typical supports include oxide substrates and porous carbon materials. The HPA's show some instability on these supports however. In this work, we demonstrate that HPA encapsulated in sol-gel silica matrices show enhanced catalytic performance without compromising the catalytic activity of the HPA. In addition, the specific role of the support in the catalytic process is described as well.

Insights into the role of strontium in toluene catalytic combustion over La1-xSrxCoO3 perovskites catalysts

2022 ◽  
Author(s):  
Mo Liu ◽  
Xiaoli Yang ◽  
ZiMeng Tian ◽  
Huimin Wang ◽  
Liangtao Yin ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Catalytic Combustion ◽  
Sol Gel ◽  
Gel Method ◽  
Sol Gel Method ◽  
A Site

A series of LaCoO3 pervoskite catalysts substituted by Sr in A site (La1-xSrxCoO3) were prepared via a facile sol-gel method. The catalytic activity of these pervoskite catalysts for the deep...

Investigation of ZnO/CuO/Nanographene Platelets Composites Catalyst for the Degradation of Methylene Blue from Aqueous Solution

2016 ◽  
Vol 864 ◽  
pp. 117-122 ◽  
Author(s):  
Hesni Shabrany ◽  
Hendry Tju ◽  
Ardiansyah Taufik ◽  
Rosari Saleh
Keyword(s):  
Aqueous Solution ◽  
Methylene Blue ◽  
Catalytic Activity ◽  
Visible Light ◽  
Sol Gel ◽  
Nitrogen Adsorption ◽  
Ultrasound Irradiation ◽  
X Ray Diffraction ◽  
X Ray

This paper discusses the catalytic activity of ZnO/CuO/nanographene platelets composites under visible light and ultrasound irradiation separately. The ZnO/CuO/nanographene platelets composites were synthesized using a sol-gel method. X-ray diffraction and nitrogen adsorption spectroscopy were employed to investigate the structural and surface area of the catalyst. The catalytic activity results showed that the presence of nanographene platelets in ZnO/CuO nanocomposites improved its efficiency in degrading methylene blue. A scavenger method was also used to understand the role of charged carriers and the active radical involved in the catalytic activity.

Rhenium and manganese modified activated carbon as catalyst for methanol decomposition

2007 ◽  
Vol 85 (2) ◽  
pp. 118-123 ◽  
Author(s):  
T Tsoncheva ◽  
S Vankova ◽  
O Bozhkov ◽  
D Mehandjiev
Keyword(s):  
Catalytic Activity ◽  
Activated Carbon ◽  
Carbon Materials ◽  
Catalytic Properties ◽  
Methanol Decomposition ◽  
Complex Character ◽  
Active Centre ◽  
Modified Activated Carbon

Bicomponent manganese and rhenium modified activated carbon materials, prepared by different methods, are studied and compared with the corresponding monocomponent materials as catalysts in methanol decomposition to CO and hydrogen. The best catalytic activity and stability is observed for the sample obtained by simultaneous deposition of Mn and Re precursors. The complex character of the catalytic active centre, including manganese and rhenium irons in various oxidative states, is discussed. The determining role of the Mn(II) ions in the improvement of the catalytic properties is assumed.Key words: rhenium, manganese, activated carbon, methanol decomposition.

scholarly journals Lanthanum-Based Perovskite-Type Oxides La1−xCexBO3(B = Mn and Co) as Catalysts: Synthesis and Characterization

2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Nyamdavaa Erdenee ◽  
Uyanga Enkhnaran ◽  
Sevjidsuren Galsan ◽  
Altantsog Pagvajav
Keyword(s):  
Catalytic Activity ◽  
Sol Gel ◽  
Catalytic Performance ◽  
Reduction Behavior ◽  
Process Characterization ◽  
Lattice Geometry ◽  
Sol Gel Process ◽  
Ce Substitution ◽  
Crystallite Sizes ◽  
Perovskite Type

La1−xCexCoO3(x= 0, 0.2, 0.4) and La1−xCexMnO3(x= 0, 0.2) perovskite-type oxides were prepared by sol-gel process. Characterization techniques EDS, FTIR, XRD, BET, and XPS experiments were performed to survey the composition, bulk structure, and the surface properties of perovskites. The reduction behavior, thermal stability, and catalytic activity were studied by H2-TPR and catalytic performance. All synthesized samples showed well crystalline perovskite structure, 8–22 nm crystallite sizes, and SSA with 2–27 m2 g−1. The XRD results showed that the Ce substitution promoted the structural transformation for LaCoO3from rhombohedral into cubic and for LaMnO3no change in lattice geometry. Substitution with cerium (x= 0.2) showed smaller crystallite size, higher SSA, and the highest reducibility and catalytic activity for LaCoO3.

The Effect of Sodium Hydroxide Concentration on the Structure of Iron Oxides@Bacterial Cellulose and their Catalytic Activity for Methylene Blue Degradation in Solution

2021 ◽  
Vol 891 ◽  
pp. 62-67
Author(s):  
Maradhana Agung Marsudi ◽  
Fakhri Arsyi Hawari ◽  
Ade Wahyu Y.P. Parmita ◽  
Untung Triadhi ◽  
Husaini Ardy ◽  
...  
Keyword(s):  
Methylene Blue ◽  
Catalytic Activity ◽  
Sodium Hydroxide ◽  
Bacterial Cellulose ◽  
Large Scale ◽  
Sol Gel ◽  
Catalyst Support ◽  
Catalytic Performance ◽  
Main Crystalline Phase ◽  
Blue Solution

Heterogeneous fenton , although offering promises for large scale wastewater treatment, is still hindered in its practicality due to its modest catalytic activity. The usage of catalyst supportas been demonstrated previously toecrease the overall particle size to improve its catalytic performance. In this demonstration, fenton catalysts were prepared using the sol-gel method and bacterial cellulose (BC) as catalyst support, with varying sodium hydroxide (NaOH) concentrations (0.01; 0.1 and 1 M). NaCl impurities' presence was successfully eliminated by reducing NaOH concentration relative to the previous 4 M concentration. Lower NaOH concentration leads to a more favorable condition for the formation of smaller non-agglomerated particles and magnetite (Fe3O4) as its main crystalline phase. It was found that the best performing catalyst was produced using 1 M NaOH and was able to degrade Methylene blue solution up to 53.8% remaining dye concentration within two hours.

scholarly journals Catalytic Properties of Phosphate-Coated CuFe2O4 Nanoparticles for Phenol Degradation

2019 ◽  
Vol 2019 ◽  
pp. 1-8 ◽  
Author(s):  
Israa Othman ◽  
Mohammad Abu Haija ◽  
Fawzi Banat
Keyword(s):  
Catalytic Activity ◽  
Sol Gel ◽  
Phenol Degradation ◽  
Chemical Properties ◽  
Complete Removal ◽  
Catalytic Performance ◽  
Copper Ferrite ◽  
Experimental Conditions ◽  
Prepared Nanoparticles ◽  
And Chemical Properties

Copper ferrite (CuFe2O4) nanoparticles were prepared using the sol-gel autocombustion method and then coated with phosphate using different treatments with H3PO4. The structural and chemical properties of the phosphate-coated CuFe2O4 nanoparticles were controlled by changing the concentration of H3PO4 during the coating process. The prepared nanoparticles were characterized using XRD, FTIR, SEM, and EDS which provided information about the catalysts’ structure, chemical composition, purity, and morphology. The catalytic and photocatalytic activities of the phosphate-coated CuFe2O4 samples were tested and evaluated for the degradation of phenol using HPLC. The prepared nanoparticles successfully emerged as excellent heterogeneous Fenton-type catalysts for phenol degradation. The phosphate-coated CuFe2O4 catalysts exhibited a higher catalytic activity compared with the uncoated CuFe2O4 ones. Such a higher catalytic performance can be attributed to enhanced morphological, electronic, and chemical properties of the phosphate-coated CuFe2O4 nanoparticles. Additionally, the phosphate-coated CuFe2O4 nanoparticles also revealed a higher catalytic activity compared with TiO2 nanoparticles. Different experimental conditions were investigated, and complete removal of phenol was achieved under specific conditions.

scholarly journals Silica Sol-Gel Entrapment of the Enzyme Chloroperoxidase

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Tuan Le ◽  
Selina Chan ◽  
Bassem Ebaid ◽  
Monika Sommerhalter
Keyword(s):  
Pore Diameter ◽  
Sol Gel ◽  
Porous Silica ◽  
Catalytic Performance ◽  
Relative Activity ◽  
Silica Sol ◽  
Average Pore ◽  
Visible Absorption ◽  
Gel Beads ◽  
Methanol Exposure

The enzyme chloroperoxidase (CPO) was immobilized in silica sol-gel beads prepared from tetramethoxysilane. The average pore diameter of the silica host structure (~3 nm) was smaller than the globular CPO diameter (~6 nm) and the enzyme remained entrapped after sol-gel maturation. The catalytic performance of the entrapped enzyme was assessed via the pyrogallol peroxidation reaction. Sol-gel beads loaded with 4 μg CPO per mL sol solution reached 9–12% relative activity compared to free CPO in solution. Enzyme kinetic analysis revealed a decrease inkcatbut no changes inKMorKI. Product release or enzyme damage might thus limit catalytic performance. Yet circular dichroism and visible absorption spectra of transparent CPO sol-gel sheets did not indicate enzyme damage. Activity decline due to methanol exposure was shown to be reversible in solution. To improve catalytic performance the sol-gel protocol was modified. The incorporation of 5, 20, or 40% methyltrimethoxysilane resulted in more brittle sol-gel beads but the catalytic performance increased to 14% relative to free CPO in solution. The use of more acidic casting buffers (pH 4.5 or 5.5 instead of 6.5) resulted in a more porous silica host reaching up to 18% relative activity.

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