Oxygen Radicals Occlusion/Release Behavior of Nanoporous Aluminosilicate, Ca12Al14-XSiXO33+0.5X (0≦X≦4)

2006 ◽  
Vol 45 ◽  
pp. 2105-2109
Author(s):  
Makoto Nagashima ◽  
Daisuke Hirabayashi ◽  
Kenzi Suzuki
Keyword(s):  
Catalytic Activity ◽  
Oxygen Content ◽  
Oxygen Radicals ◽  
Catalytic Performance ◽  
Oxygen Release ◽  
Release Behavior ◽  
Temperature Programmed Reduction ◽  
Temperature Programmed Oxidation ◽  
Temperature Range ◽  
Temperature Programmed

Oxygen radicals occlusion / release behavior of nanoporous aluminosilicate, Ca12Al14-XSiXO33+0.5X (0≦X≦4), synthesized under different condition was examined by the temperature programmed reduction (TPR) in an atmosphere of hydrogen in the temperature range of 200-1000°C and temperature programmed oxidation (TPO) measurement at 800°C. From the TPR results of Ca12Al14O33 (X=0) and Ca12Al10Si4O35 (X=4), it was found that there were three oxygen release peaks, denoted as α, β and γ, on each sample and the peaks appeared in the temperature range 300-420°C, 420-600°C, and 600-750°C, respectively. The oxygen contents of α and γ of samples were almost the same. However, the oxygen content of β in the sample with x = 4 was much larger, almost double, compared to that in x = 0. From the TPR, TPO results and catalytic performance, it was concluded that the oxygen content of β peak strongly influenced the catalytic activity of the nanoporous aluminosilicate in the propylene combustion.

scholarly journals Novel Nickel- and Magnesium-Modified Cenospheres as Catalysts for Dry Reforming of Methane at Moderate Temperatures

Catalysts ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 1066 ◽  
Author(s):  
Bogdan Samojeden ◽  
Marta Kamienowska ◽  
Armando Izquierdo Colorado ◽  
Maria Elena Galvez ◽  
Ilona Kolebuk ◽  
...  
Keyword(s):  
Supported Catalysts ◽  
Temperature Programmed Desorption ◽  
Catalytic Performance ◽  
Dry Reforming ◽  
Dry Reforming Of Methane ◽  
Temperature Programmed Reduction ◽  
Fly Ashes ◽  
Coal Fly Ashes ◽  
Temperature Programmed ◽  
Mg Content

Cenospheres from coal fly ashes were used as support in the preparation of Ni–Mg catalysts for dry reforming of methane. These materials were characterized by means of XRD, H2-temperature-programmed reduction (H2-TPR), CO2-temperature-programmed desorption (CO2-TPD), and low-temperature nitrogen sorption techniques. The cenosphere-supported catalysts showed relatively high activity and good stability in the dry reforming of methane (DRM) at 700 °C. The catalytic performance of modified cenospheres was found to depend on both Ni and Mg content. The highest activity at 750 °C and 1 atm was observed for the catalyst containing 30 wt % Mg and 10, 20, and 30 wt % Ni, yielding to CO2 and CH4 conversions of around 95%.

scholarly journals Precipitated K-Promoted Co–Mn–Al Mixed Oxides for Direct NO Decomposition: Preparation and Properties

Catalysts ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 592 ◽  
Author(s):  
Květa Jirátová ◽  
Kateřina Pacultová ◽  
Jana Balabánová ◽  
Kateřina Karásková ◽  
Anna Klegová ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Mixed Oxides ◽  
No Decomposition ◽  
Temperature Programmed Reduction ◽  
X Ray ◽  
Co2 Desorption ◽  
Metal Nitrates ◽  
Temperature Programmed ◽  
Desorption Method ◽  
Al Oxide

Direct decomposition of nitric oxide (NO) proceeds over Co–Mn–Al mixed oxides promoted by potassium. In this study, answers to the following questions have been searched: Do the properties of the K-promoted Co–Mn–Al catalysts prepared by different methods differ from each other? The K-precipitated Co–Mn–Al oxide catalysts were prepared by the precipitation of metal nitrates with a solution of K2CO3/KOH, followed by the washing of the precipitate to different degrees of residual K amounts, and by cthe alcination of the precursors at 500 °C. The properties of the prepared catalysts were compared with those of the best catalyst prepared by the K-impregnation of a wet cake of Co–Mn–Al oxide precursors. The solids were characterized by chemical analysis, DTG, XRD, N2 physisorption, FTIR, temperature programmed reduction (H2-TPR), temperature programmed CO2 desorption (CO2-TPD), X-ray photoelectron spectrometry (XPS), and the species-resolved thermal alkali desorption method (SR-TAD). The washing of the K-precipitated cake resulted in decreasing the K amount in the solid, which affected the basicity, reducibility, and non-linearly catalytic activity in NO decomposition. The highest activity was found at ca 8 wt.% of K, while that of the best K-impregnated wet cake catalyst was at about 2 wt.% of K. The optimization of the cake washing conditions led to a higher catalytic activity.

scholarly journals Comparison of Two Preparation Methods on Catalytic Activity and Selectivity of Ru-Mo/HZSM5 for Methane Dehydroaromatization

2014 ◽  
Vol 2014 ◽  
pp. 1-7
Author(s):  
Lucia M. Petkovic ◽  
Daniel M. Ginosar
Keyword(s):  
Molybdenum Carbide ◽  
Molybdenum Trioxide ◽  
Catalyst Activity ◽  
Catalytic Performance ◽  
Preparation Methods ◽  
Ammonium Heptamolybdate ◽  
Temperature Programmed Oxidation ◽  
Methane Dehydroaromatization ◽  
Acidic Sites ◽  
Temperature Programmed

Catalytic performance of Mo/HZSM5 and Ru-Mo/HZSM5 catalysts prepared by vaporization-deposition of molybdenum trioxide and impregnation with ammonium heptamolybdate was analyzed in terms of catalyst activity and selectivity, nitrogen physisorption analyses, temperature-programmed oxidation of carbonaceous residues, and temperature-programmed reduction. Vaporization-deposition rendered the catalyst more selective to ethylene and coke than the catalyst prepared by impregnation. This result was assigned to lower interaction of molybdenum carbide with the zeolite acidic sites.

Preparation and Characterization of Ni-Modified Fe-Mo and Catalytic Selective Oxidation of p-Xylene

2012 ◽  
Vol 557-559 ◽  
pp. 1501-1504 ◽  
Author(s):  
Zu Zeng Qin ◽  
Zi Li Liu ◽  
Yan Bin Liu ◽  
Rui Wen Liu
Keyword(s):  
Photoelectron Spectrum ◽  
Sol Gel ◽  
Catalytic Performance ◽  
Ni Catalyst ◽  
Temperature Programmed Reduction ◽  
X Ray ◽  
Mo Catalyst ◽  
Ft Ir ◽  
Temperature Programmed

The preparation of the Fe-Mo-Ni catalyst using the sol-gel method was investigated. In addition, the catalytic selective oxidations of p-xylene (PX) to terephthalaldehyde (TPAL) on the Fe-Mo-Ni catalyst were also investigated. The catalysts were characterized using thermal analysis, H2-temperature programmed reduction (H2-TPR), Fourier transform infrared spectra (FT-IR), and X-ray photoelectron spectrum (XPS). The additional of Ni improves the catalytic activity of the Fe-Mo catalyst on selective oxidations of PX to TPAL. The optimal additive amount of Ni is 5%. XPS analysis shows that the introduction of Ni changes the internal structure of the Fe-Mo catalyst improves catalytic performance.

Effect of Ni Reducibility on Anisole Hydrodeoxygenation Activity in the La-Ni/γ-Al2O3 Catalytic System

2019 ◽  
Vol 18 (2) ◽  
Author(s):  
Brett Pomeroy ◽  
Teri Doxtator ◽  
Jose E. Herrera ◽  
Dominic Pjontek
Keyword(s):  
Catalytic Activity ◽  
Catalytic System ◽  
Catalyst Surface ◽  
Reaction Pathway ◽  
Catalyst Characterization ◽  
Temperature Programmed Reduction ◽  
Visible Spectroscopy ◽  
Uv Visible ◽  
Temperature Programmed

Abstract The effect of lanthanum addition on the activity of a series of Ni/γ-Al2O3 catalysts for anisole hydrodeoxygenation (HDO) was evaluated. Catalyst characterization using hydrogen temperature-programmed reduction (H2-TPR) and UV-visible spectroscopy suggests that lanthanum incorporation results in the formation of larger metallic Ni domains in the catalyst surface, which in turn favour the direct anisole hydrogenation pathway to methoxycyclohexane. Despite the improvements to reducibility that resulted from the incorporation of La, the catalysts displayed lower selectivity towards cyclohexane, independent of total nickel loading. The catalytic activity results were rationalized in terms of a proposed reaction pathway where anisole is initially hydrogenated followed by sequential deoxygenation steps.

scholarly journals Effect of Copper Precursors on the Activity and Hydrothermal Stability of CuII−SSZ−13 NH3−SCR Catalysts

Catalysts ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 781
Author(s):  
Meixin Wang ◽  
Zhaoliang Peng ◽  
Changming Zhang ◽  
Mengmeng Liu ◽  
Lina Han ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Adsorption Capacity ◽  
Photoelectron Spectroscopy ◽  
Hydrothermal Stability ◽  
Vehicle Exhaust ◽  
No Conversion ◽  
X Ray ◽  
Temperature Range ◽  
Scr Catalysts ◽  
Temperature Programmed

A series of CuII−SSZ−13 catalysts are prepared by in-situ hydrothermal method using different copper precursors (CuII(NO3)2, CuIISO4, CuIICl2) for selective catalytic reduction of NO by NH3 in a simulated diesel vehicle exhaust. The catalysts were characterized by X−ray diffraction (XRD), scanning electron microscope (SEM), X−ray photoelectron spectroscopy (XPS), N2 adsorption-desorption, hydrogen-temperature-programmed reduction (H2−TPR), ammonia temperature-programmed desorption (NH3−TPD), and 27Al and 29Si solid state Nuclear Magnetic Resonance (NMR). The CuII−SSZ−13 catalyst prepared by CuII(NO3)2 shows excellent catalytic activity and hydrothermal stability. The NO conversion of CuII−SSZ−13 catalyst prepared by CuII(NO3)2 reaches 90% at 180 °C and can remain above 90% at a wide temperature range of 180–700 °C. After aging treatment at 800 °C for 20 h, the CuII−SSZ−13 catalyst prepared by CuII(NO3)2 still exhibits above 90% NO conversion under a temperature range of 240–600 °C. The distribution of Cu species and the Si/Al ratios in the framework of the synthesized CuII−SSZ−13 catalysts, which determine the catalytic activity and the hydrothermal stability of the catalysts, are dependent on the adsorption capacity of anions to the cation during the crystallization process due to the so called Hofmeister anion effects, the NO3− ion has the strongest adsorption capacity among the three kinds of anions (NO3−, Cl−, and SO42−), followed by Cl– and SO42– ions. Therefore, the CuII−SSZ−13 catalyst prepared by CuII(NO3)2 possess the best catalytic ability and hydrothermal stability.

The Different Morphology of Co3O4 Catalysts and Application in the Abatement of Carbon Monoxide

2021 ◽  
Vol 21 (12) ◽  
pp. 6082-6087
Author(s):  
Chih-Wei Tang ◽  
Hsiang-Yu Shih ◽  
Ruei-Ci Wu ◽  
Chih-Chia Wang ◽  
Chen-Bin Wang
Keyword(s):  
Carbon Monoxide ◽  
Catalytic Activity ◽  
Co Oxidation ◽  
Nitrogen Adsorption ◽  
Catalytic Performance ◽  
Precipitation Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
Temperature Programmed ◽  
Adsorption Desorption

The increase of harmful carbon monoxide (CO) caused by incomplete combustion can affect human health even lead to suffocation. Therefore reducing the CO discharged by vehicles or factories is urgent to improve the air quality. The spinel cobalt (II, III) oxide (Co3O4) is an active catalyst for CO abatement. In this study, we tried to fabricate dispersing Co3O4 via the dispersion-precipitation method with acetic acid, formic acid, and oxalic acid as the chelating dispersants. Then, the asprepared samples were calcined at 300 ºC for 4 h to obtain active catalysts, and assigned as Co(A), Co(F) and Co(O) respectively, the amount of the dispersants used are labeled as I (0.12 mole), II (0.03 mole) and III (0.01 mole). For comparison, another CoAP sample was prepared via alkaliinduced precipitation and calcined at 300 ºC. All samples were characterized by X-ray diffraction (XRD), temperature-programmed reduction (TPR), scanning electron microscope (SEM), and nitrogen adsorption/desorption system, and the catalytic activity focused on the CO oxidation. The influence of chelating dispersant on the performance of abatement of CO was pursued in this study. Apparently, the results showed that the chelating dispersant can influence the catalytic activity of CO abatement. An optimized ratio of dispersant can improve the performance, while excess dispersant lessens the surface area and catalytic performance. The series of Co(O) samples can easily donate the active oxygen since the labile Co–O bonding and indicated the preferential performance than both Co(A) and Co(F) samples. The nanorod Co(O)-II showed preferential for CO oxidation, T50 and T90 approached 96 and 127 ºC, respectively. Also, the favorable durability of Co(O)-II sample maintains 95% conversion still for 50 h at 130 ºC and does not emerge deactivation.

One-Step FSP Synthesis of Nanocrystalline Fe/Al2O3 and Fe-Ce/Al2O3 Catalyst for CO2 Hydrogenation Reaction

2018 ◽  
Vol 916 ◽  
pp. 134-138 ◽  
Author(s):  
Kanyarat Piriyasurawong ◽  
Sunthon Piticharoenphun ◽  
Okorn Mekasuwandumrong
Keyword(s):  
Catalytic Activity ◽  
Iron Oxide ◽  
Catalytic Performance ◽  
Hydrogenation Reaction ◽  
Flame Spray ◽  
One Step ◽  
Temperature Programmed ◽  
The One ◽  
Long Chain ◽  
Chain Hydrocarbon

Nanocrystalline Fe/Al2O3and Fe-Ce/Al2O3catalysts doped with various amounts of cerium were prepared using the one-step flame spray pyrolysis (FSP) technique. The characterization of the catalysts was measured by several methods such as X-ray diffraction, nitrogen physisorption and hydrogen temperature programmed reduction (H2-TPR) techniques. The results revealed that the FSP-made catalyst exhibited the characteristic pattern of FeAl2O4phase without any phases of aluminum or iron oxide. In addition, cerium (Ce) dopant did not alter crystal structure at low content. However, 7 wt% content of cerium dopant resulted in the formation of ceria (CeO) and iron oxide (Fe2O3) phase. The catalytic performance of the FSP-made catalyst was tested in carbon dioxide hydrogenation for selective production of long chain hydrocarbon, and was compared to conventional impregnation-made catalysts. In the comparison, the FSP-made catalyst exhibited lower catalytic activity but possessed a higher long chain hydrocarbon selectivity. After doping with Ce, the catalytic activity was improved while the hydrocarbon selectivity was decreased and shifted to the short chain hydrocarbon product. In the case of conventional-made catalysts, the activity remained unchanged but the hydrocarbon selectivity was decreased. Among all catalysts, the FSP-made Fe-Ce/Al2O3catalyst with 3% Ce-promoted catalyst exhibited the best performance in terms of selectivity to long chain hydrocarbon.

Catalytic Performance of Supported Bimetallic Catalysts for Complete Oxidation of Toluene

2021 ◽  
Vol 21 (7) ◽  
pp. 4060-4066
Author(s):  
Sang-Chul Jung ◽  
Young-Kwon Park ◽  
Ho-Young Jung ◽  
Sang Chai Kim
Keyword(s):  
Catalytic Activity ◽  
Transition Metal ◽  
Bimetallic Catalysts ◽  
Xrd Analysis ◽  
Catalytic Performance ◽  
Bet Surface Area ◽  
Complete Oxidation ◽  
Transmission Electron ◽  
The Difference ◽  
Temperature Programmed

The complete oxidation of toluene (as a model volatile organic compound) was studied to determine the influence of adding a transition metal (Mn, Cr, Fe, Co, and Ni) to the 5 Cu/Al catalyst. The physcochemical properties of the catalysts were characterized by Brunauer–Emmett–Teller (BET) surface area analysis, X-ray diffraction (XRD) analysis, field emission transmission electron microscopy (FE/TEM), and hydrogen temperature programmed reduction (H2-TPR). The catalytic activity of the supported bimetallic catalysts followed the order: 5Cu-5Mn/Al > 5Cu-5Cr/Al > 5Cu-5Fe/Al > 5Cu-5Co/Al > 5Cu > 5Cu-5Ni/Al, based on the temperature for T90 of toluene conversion (T90). Two different reaction mechanisms (mixing and the synergistic effect) were operative in the supported bimetallic catalysts except for the 5Cu–5Mn/Al and 5Cu–5Ni/Al catalysts, on the basis of the reaction temperature. The difference between the electronegativity of copper and the added transition metal was associated with the catalytic activity.

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