Efficient CO oxidation over palladium supported on various MOFs: Synthesis, amorphization, and space velocity of hydrogen stream

Ceria in nanoscale with different morphologies, rod, tube and cube, were prepared through a hydrothermal process. The structure, morphology and textural properties were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM) and isothermal N2 adsorption-desorption. Ceria with different morphologies were evaluated as catalysts for CO oxidation. CeO2 nanorods showed superior activity to the others. When space velocity was 12,000 mL·gcat−1·h−1, the reaction temperature for 90% CO conversion (T90) was 228 °C. The main reason for the high activity was the existence of large amounts of easily reducible oxygen species, with a reduction temperature of 217 °C on the surface of CeO2 nanorods. Another cause was their relatively large surface area.

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A kinetic study of Co oxidation over the perovskite-like oxide LaSrNio4

Journal of the Serbian Chemical Society ◽

10.2298/jsc1002249w ◽

2010 ◽

Vol 75 (2) ◽

pp. 249-258 ◽

Cited By ~ 6

Author(s):

Kejun Wang ◽

Ping Zhong

Keyword(s):

Activation Energy ◽

Co Oxidation ◽

Reaction Order ◽

Space Velocity ◽

Potential Candidate ◽

Weight Hourly Space Velocity ◽

Rate Determining Step ◽

Co Oxidation Reaction ◽

Oxygen Dissociation ◽

Reaction Orders

The effect of reactant/product concentrations, reaction temperature and contact time on CO oxidation was investigated, using the perovskite-like oxide LaSrNiO4 as the catalyst. It was found that the reaction order of CO (reactant), as well as that of CO2 (product), is negative, the reaction orders for CO and CO2 being -0.32 and -0.51, respectively. However, the reaction order for O2 is positive, having a value of 0.62. The negative reaction order of CO and CO2 might be due to their competitive adsorption with O2, preventing the proceeding of oxygen dissociation (the rate-determining step of the reaction). The activation energy (Ea) of the reaction was calculated to be 49.3 kJ mol-1; this small activation energy suggests that LaSrNiO4 is a potential candidate for the CO oxidation reaction. The optimum weight hourly space velocity (WHSV) of the reaction was found to be 0.6 g s cm-3. The reaction conditions in the present case were (0.5-1 % CO + 0.5-2 % O2 + 0-2 % CO2), with He as the balance gas.

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Forced Unsteady State Operation of a Catalytic Converter during Cold Start-up for Oxidizing CO Over Pt/γ-Al2O3 Catalyst

MATEC Web of Conferences ◽

10.1051/matecconf/202133305003 ◽

2021 ◽

Vol 333 ◽

pp. 05003

Author(s):

Yogi Wibisono Budhi ◽

Ade Kusuma Putri ◽

Alimatun Nashira

Keyword(s):

Steady State ◽

Co Oxidation ◽

Switching Time ◽

Catalytic Converter ◽

Cold Start ◽

Space Velocity ◽

State System ◽

Unsteady State ◽

Start Up ◽

Co Conversion

CO oxidation in the catalytic converter hasn’t showed best performance particularly during cold start-up, since the catalyst is not active during this period. The purpose of this experiment was to develop the forced unsteady state operation procedure of CO oxidation using 0.05%-w Pt/γ-Al2O3 and space velocity of 0.406 mmol/s/gram. The catalytic converter was gradually ramped-up, while introducing the feed gas containing CO in the air. The feed gas was modulated following a square wave model with switching time variation at 3, 6, 15, and 30 s and various operation modes. To gain the intrinsic reaction rate, the external mass transfer criterion was determined. Ramping-up the temperature from 50 until 150°C increased the CO conversion with different profiles between steady state and dynamic flow rate. The dynamic system with modulated CO feed flow gave lower light-off temperature and higher average CO conversion than the steady state system which gave light off temperature 115°C and average CO conversion of 48.86%. The switching time of 3 s gave highest average CO conversion during ramping-up, which was 79.35%. Meanwhile the dynamic operation system with modulated feed flow gave higher lightoff temperature and lower average CO conversion than steady state system.

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Pt–Ni/γ-Al2O3 catalyst for the preferential CO oxidation in the hydrogen stream

Catalysis Letters ◽

10.1007/s10562-006-0121-z ◽

2006 ◽

Vol 110 (3-4) ◽

pp. 275-279 ◽

Cited By ~ 57

Author(s):

Eun-Yong Ko ◽

Eun Duck Park ◽

Kyung Won Seo ◽

Hyun Chul Lee ◽

Doohwan Lee ◽

...

Keyword(s):

Co Oxidation ◽

Preferential Co Oxidation ◽

Al2o3 Catalyst ◽

Hydrogen Stream

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Low-temperature CO oxidation over Cu/Pt co-doped ZrO2 nanoparticles synthesized by solution combustion

Beilstein Journal of Nanotechnology ◽

10.3762/bjnano.8.156 ◽

2017 ◽

Vol 8 ◽

pp. 1546-1552 ◽

Cited By ~ 13

Author(s):

Amit Singhania ◽

Shipra Mital Gupta

Keyword(s):

Co Oxidation ◽

Oxygen Vacancies ◽

Space Velocity ◽

High Specific Surface Area ◽

Zro2 Nanoparticles ◽

Solution Combustion ◽

Charge Imbalance ◽

Highly Active ◽

Low Temperature Co Oxidation ◽

Co Doped

Zirconia (ZrO2) nanoparticles co-doped with Cu and Pt were applied as catalysts for carbon monoxide (CO) oxidation. These materials were prepared through solution combustion in order to obtain highly active and stable catalytic nanomaterials. This method allows Pt2+ and Cu2+ ions to dissolve into the ZrO2 lattice and thus creates oxygen vacancies due to lattice distortion and charge imbalance. High-resolution transmission electron microscopy (HRTEM) results showed Cu/Pt co-doped ZrO2 nanoparticles with a size of ca. 10 nm. X-ray diffraction (XRD) and Raman spectra confirmed cubic structure and larger oxygen vacancies. The nanoparticles showed excellent activity for CO oxidation. The temperature T 50 (the temperature at which 50% of CO are converted) was lowered by 175 °C in comparison to bare ZrO2. Further, they exhibited very high stability for CO reaction (time-on-stream ≈ 70 h). This is due to combined effect of smaller particle size, large oxygen vacancies, high specific surface area and better thermal stability of the Cu/Pt co-doped ZrO2 nanoparticles. The apparent activation energy for CO oxidation is found to be 45.6 kJ·mol−1. The CO conversion decreases with increase in gas hourly space velocity (GHSV) and initial CO concentration.

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Nanocrystalline ZrO2 and Pt-doped ZrO2 catalysts for low-temperature CO oxidation

Beilstein Journal of Nanotechnology ◽

10.3762/bjnano.8.29 ◽

2017 ◽

Vol 8 ◽

pp. 264-271 ◽

Cited By ~ 23

Author(s):

Amit Singhania ◽

Shipra Mital Gupta

Keyword(s):

Co Oxidation ◽

Oxygen Vacancies ◽

Space Velocity ◽

Gravimetric Analysis ◽

X Ray Diffraction ◽

Solution Combustion ◽

Charge Imbalance ◽

Transmission Electron ◽

Co Conversion ◽

Low Temperature Co Oxidation

Zirconia (ZrO2) nanoparticles were synthesized by solution combustion using urea as an organic fuel. Brunauer–Emmett–Teller (BET), X-ray diffraction (XRD), thermal gravimetric analysis (TGA), transmission electron microscopy (TEM), UV–vis and Fourier transform infrared (FTIR) measurements were performed in order to characterize the catalyst. The calculated crystallite size of ZrO2, calculated with the help of the Scherrer equation, was around 30.3 nm. The synthesized ZrO2 was scrutinized regarding its role as catalyst in the oxidation of carbon monoxide (CO). It showed 100% CO conversion at 240 °C, which is the highest conversion rate reported for ZrO2 in literature to date. It is found that through solution combustion, Pt2+ ions replace Zr4+ ions in the ZrO2 lattice and because of this, oxygen vacancies are formed due to charge imbalance and lattice distortion in ZrO2. 1% Pt was doped into ZrO2 and yielded excellent CO oxidation. The working temperature was lowered by 150 °C in comparison to pure ZrO2. Further, it is highly stable for the CO reaction (time-on-stream ≈ 40 h). This is because of a synergic effect between Pt and Zr components, which results in an increase of the oxygen mobility and oxygen vacancies and improves the activity and stability of the catalyst. The effects of gas hourly space velocity (GHSV) and initial CO concentration on the CO oxidation over Pt(1%)-ZrO2 were studied.

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