scholarly journals Role of CO2 During Oxidative Dehydrogenation of Propane Over Bulk and Activated-Carbon Supported Cerium and Vanadium Based Catalysts

2021 ◽  
Author(s):  
Petar Djinović ◽  
Janez Zavašnik ◽  
Janvit Teržan ◽  
Ivan Jerman
Keyword(s):  
Catalytic Activity ◽  
Activated Carbon ◽  
Oxidative Dehydrogenation ◽  
Active Phase ◽  
Lattice Oxygen ◽  
Chemisorbed Oxygen ◽  
Catalytically Active ◽  
Temperature Programmed ◽  
Propane Cracking

AbstractCeO2, V2O5 and CeVO4 were synthesised as bulk oxides, or deposited over activated carbon, characterized by XRD, HRTEM, CO2-TPO, C3H8-TPR, DRIFTS and Raman techniques and tested in propane oxidative dehydrogenation using CO2. Complete oxidation of propane to CO and CO2 is favoured by lattice oxygen of CeO2. The temperature programmed experiments show the ~ 4 nm AC supported CeO2 crystallites become more susceptible to reduction by propane, but less prone to re-oxidation with CO2 compared to bulk CeO2. Catalytic activity of CeVO4/AC catalysts requires a 1–2 nm amorphous CeVO4 layer. During reaction, the amorphous CeVO4 layer crystallises and several atomic layers of carbon cover the CeVO4 surface, resulting in deactivation. During reaction, V2O5 is irreversibly reduced to V2O3. The lattice oxygen in bulk V2O5 favours catalytic activity and propene selectivity. Bulk V2O3 promotes only propane cracking with no propene selectivity. In VOx/AC materials, vanadium carbide is the catalytically active phase. Propane dehydrogenation over VC proceeds via chemisorbed oxygen species originating from the dissociated CO2. Graphic Abstract

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 H2-TPR, XPS and TEM Study of the Reduction of Ru and Re promoted Co/γ-Al2O3, Co/TiO2 and Co/SiC Catalysts

2016 ◽  
Vol 5 (2) ◽  
pp. 39 ◽  
Author(s):  
H. Romar ◽  
A. H. Lillebo ◽  
P. Tynjala ◽  
T. Hu ◽  
A. Holmen ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Metallic Nanoparticles ◽  
Surface Composition ◽  
Active Phase ◽  
Support Materials ◽  
Metal Support Interaction ◽  
Active Metal ◽  
Metal Support ◽  
Oxide Phases

<p class="1Body">Effects of Ru and Re promoters on Co-CoO<sub>x </sub>catalysts supported on γ-Al<sub>2</sub>O<sub>3</sub>, TiO<sub>2</sub> and SiC were investigated to improve the understanding of the role of promoters of the active phase of Co-CoO<sub>x</sub>-Ru and Co-CoO<sub>x</sub>-Re. The influence of promoter addition on the composition and activity of the catalysts was characterized by several methods, such as H<sub>2</sub>-TPR, XPS, chemisorption and TEM. Furthermore, the role of support and metal-support interaction was especially studied and different support materials were compared.</p><p class="1Body">Based on the results, addition of promoter metals (Ru or Re) will most likely improve catalytic activity of Co/γ-Al<sub>2</sub>O<sub>3</sub>, Co/TiO<sub>2</sub> and Co/SiC catalysts by increasing the active metal surface available for chemical reaction and by decreasing the size of the metallic nanoparticles. These changes in the catalytic activity were also associated with the changes in the ratio of metal and metal oxide phases in the surface composition as observed by XPS. Promoter metals also decreased the reduction temperatures needed for the reduction of Co<sub>3</sub>O<sub>4</sub> to CoO and further to metallic cobalt. Significant decrease in reduction temperature was observed especially when ruthenium was used as the promoter.</p>

The role of active phase in Ce modified BiMo catalysts for oxidative dehydrogenation of 1-butene

2016 ◽  
Vol 264 ◽  
pp. 180-184 ◽  
Author(s):  
Chao Wan ◽  
Dang-guo Cheng ◽  
Fengqiu Chen ◽  
Xiaoli Zhan
Keyword(s):  
Oxidative Dehydrogenation ◽  
Active Phase

scholarly journals Dehydration of isopropyl alcohol with activated carbon functionalized with Br- and S-containing reagents

2021 ◽  
pp. 90-99
Author(s):  
L.M. Grishchenko ◽  
◽  
A.N. Zaderko ◽  
G.G. Tsapyuk ◽  
I.P. IMatushko ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Activated Carbon ◽  
Isopropyl Alcohol ◽  
Surface Concentration ◽  
Complete Conversion ◽  
Modified Activated Carbon ◽  
Liquid Bromine ◽  
Catalytically Active ◽  
Hydrolysis Conditions ◽  
Sulfur Containing

Bromination of activated carbon GSGD was performed and active bromine-containing precursors were obtained, in which bromine is capable of being replaced by sulfur-containing functional groups. Bromination with liquid bromine and a solution of bromine in potassium bromide at room temperature leads to the introduction of 0.44–0.45 mmol g–1 of bromine into the surface layer of activated carbon. The treatment of brominated samples with sulfur-containing reagents with subsequent oxidation allows obtaining carbon samples that are catalytically active in the dehydration reaction of isopropyl alcohol in a gas phase. The temperature of complete conversion of isopropyl alcohol to propylene is a measure of catalytic activity. The concentration of sulfogroups in the prepared samples is up to 0.3 mol g–1. Thermogravimetry and thermoprogrammed desorption with mass spectrometric registration of products were used to study the thermal stability of modified activated carbon samples. The influence of the nature of brominating reagents, hydrolysis conditions and oxidation conditions on the structure, surface concentration of grafted S-containing groups and catalytic properties of the obtained materials was studied. Pre-bromination leads to an increase in the catalytic activity of activated carbon modified with sulfur-containing groups and the temperature of complete conversion of isopropyl alcohol to propylene decreases up to 400C depending on the concentration of sulfogroups.

The Role of Particles and Clusters Size on the Catalytic Activity of Different Types of Gold Nanocatalysts for Benzyl Alcohol Oxidation

2021 ◽  
Vol 69 ◽  
pp. 67-76
Author(s):  
Sedigheh Ghadamgahi
Keyword(s):  
Gold Nanoparticles ◽  
Catalytic Activity ◽  
Activated Carbon ◽  
Benzyl Alcohol ◽  
Size Effects ◽  
Alcohol Oxidation ◽  
Benzyl Alcohol Oxidation ◽  
Different Types ◽  
Vulcan Carbon

: In this paper, activation procedures under size effects of some gold nanoparticles (Au101, Aunaked and Aucitrate) and nanoclusters (Au8 and Au9) immobilized on powder Norit® activated carbon (abbreviated to AC) and/or Vulcan carbon (abbreviated to VC) on the catalytic activity of gold nanocatalysts were studied. The gold nanostructures were activated through the washing procedure with a base in MilliQ water or hot toluene and then followed by heating in static air (abbreviated to W+S) or under vacuum (abbreviated to W+V) at 100 °C for 3 h. The highest activity of gold nanocatalysts for benzyl alcohol oxidation was obtained for activated (W+V) ‘naked’ gold nanoparticles immobilized on Norit® activated carbon when the gold nanoparticle diameters was ~4.4 nm.

The dual role of micelles as templates and reducing agents for the fabrication of catalytically active hollow silver nanospheres

2015 ◽  
Vol 51 (4) ◽  
pp. 733-736 ◽  
Author(s):  
Manickam Sasidharan ◽  
Chenrayan Senthil ◽  
Vandana Kumari ◽  
Asim Bhaumik
Keyword(s):  
Catalytic Activity ◽  
Oxidation Reaction ◽  
Triblock Copolymer ◽  
Reducing Agents ◽  
Dual Role ◽  
Reducing Agent ◽  
Silver Nanospheres ◽  
Catalytically Active ◽  
Villiger Oxidation

A simple and efficient protocol for fabrication of colloidal hollow Ag nanospheres of size less than 30 nm using a triblock copolymer in the absence of any reducing agent is reported, which showed excellent catalytic activity in the Baeyer–Villiger oxidation reaction.

Molecular insight into the role of the leucine residue on the L2 loop in the catalytic activity of caspases 3 and 7

2012 ◽  
Vol 32 (3) ◽  
pp. 305-313 ◽  
Author(s):  
Hyo Jin Kang ◽  
Young-mi Lee ◽  
Myeong Seon Jeong ◽  
Moonil Kim ◽  
Kwang-Hee Bae ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Caspase 3 ◽  
Tryptophan Fluorescence ◽  
Enzyme Activation ◽  
Wild Type ◽  
Leucine Residue ◽  
Catalytically Active ◽  
Caspase 7 ◽  
Insight Into

Various apoptotic signals can activate caspases 3 and 7 by triggering the L2 loop cleavage of their proenzymes. These two enzymes have highly similar structures and functions, and serve as apoptotic executioners. The structures of caspase 7 and procaspase 7 differ significantly in the conformation of the loops constituting the active site, indicating that the enzyme undergoes a large structural change during activation. To define the role of the leucine residue on the L2 loop, which shows the largest movement during enzyme activation but has not yet been studied, Leu168 of caspase 3 and Leu191 of caspase 7 were mutated. Kinetic analysis indicated that the mutation of the leucine residues sometimes improved the Km but also greatly decreased the kcat, resulting in an overall decrease in enzyme activity. The tryptophan fluorescence change at excitation/emission=280/350 nm upon L2–L2′ loop cleavage was found to be higher in catalytically active mutants, including the corresponding wild-type caspase, than in the inactive mutants. The crystal structures of the caspase 3 mutants were solved and compared with that of wild-type. Significant alterations in the conformations of the L1 and L4 loops were found. These results indicate that the leucine residue on the L2 loop has an important role in maintaining the catalytic activity of caspases 3 and 7.

scholarly journals Role of Chemisorbed Oxygen in Fixation of Palladium by an Activated Carbon, SCN-3M, from Aqueous Solution of its Complex Ion

2002 ◽  
Vol 70 (5) ◽  
pp. 316-321 ◽  
Author(s):  
Yuriy A. TARASENKO ◽  
Svitlana A. KOPYL ◽  
Vladimir F. LAPKO ◽  
Anatoliy A. LYSENKO ◽  
Isao TOMIZUKA
Keyword(s):  
Aqueous Solution ◽  
Activated Carbon ◽  
Chemisorbed Oxygen ◽  
Complex Ion

scholarly journals NO Reactions Over Ir-Based Catalysts in the Presence of O2

2011 ◽  
Vol 8 (s1) ◽  
pp. S349-S357 ◽  
Author(s):  
Mingxin Guo ◽  
Rongshu Zhu ◽  
Minhua Dong ◽  
Feng Ouyang
Keyword(s):  
Catalytic Activity ◽  
No Reduction ◽  
Active Phase ◽  
No Oxidation ◽  
Impregnation Method ◽  
Iridium Catalysts ◽  
Support Materials ◽  
Surface Active ◽  
Temperature Programmed ◽  
Temperature Programmed Reaction

The behaviour of a series of Ir-based catalysts supported on SiO2, ZSM-5 and γ-Al2O3 with various Ir loadings prepared by impregnation method was conducted by temperature programmed reaction (TPR) technique. The result implies that NO is oxidized to NO2while simultaneously being reduced to N2or N2O in the NO reactions over iridium catalysts. The surface active phase over iridium catalysts that promote the NO reactions is IrO2. The catalytic activity increases with the increase of the Ir loading and support materials have a little effect on the catalytic activity. When the loading is less than 0.1%, the catalytic activity was found to be dependent on the nature of support materials and in order: Ir/ZSM-5>Ir/γ-Al2O3>Ir/SiO2. When the loading is higher than 0.1%, the catalytic activity for NO oxidation is in order: Ir/ZSM-5>Ir/SiO2>Ir/γ -Al2O3, which is correlated with Ir dispersion on the surface of support materials and the catalytic activity for NO reduction is in sequence: Ir/γ -Al2O3>Ir/SiO2>Ir/ZSM-5, which is attributed to the adsorbed-dissociation of NO2. Compared to Pt/γ-Al2O3, Ir/γ-Al2O3catalyst is more benefit for the NO reduction.

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