Kinetic Analysis of Temperature-Programmed Reduction: Behavior of a CrOx/Al2O3Catalyst

2001 ◽  
Vol 105 (40) ◽  
pp. 9778-9784 ◽  
Author(s):  
Jaana M. Kanervo ◽  
A. Outi I. Krause
Keyword(s):  
Kinetic Analysis ◽  
Temperature Programmed Reduction ◽  
Reduction Behavior ◽  
Temperature Programmed

Reduction of Molybdenum Trioxide by Using Hydrogen

2017 ◽  
Vol 888 ◽  
pp. 404-408 ◽  
Author(s):  
Mohd Nor Latif ◽  
Alinda Samsuri ◽  
Mohamed Wahab Mohamed Hisham ◽  
Mohd Ambar Yarmo
Keyword(s):  
Molybdenum Trioxide ◽  
Reduction Step ◽  
Temperature Programmed Reduction ◽  
X Ray Diffraction ◽  
Thermodynamic Consideration ◽  
Rapid Reduction ◽  
Reduction Behavior ◽  
X Ray ◽  
Intermediate Phases ◽  
Temperature Programmed

Metallic molybdenum was synthesized through reduction of molybdenum trioxide (MoO3) by using hydrogen as a reducing agent. The reduction behavior of MoO3 were investigated by using temperature programmed reduction (TPR). The reduced phases were characterized by X-ray diffraction spectroscopy (XRD). The XRD results indicate that the reduction of MoO3 proceed in two steps reduction (MoO3 → MoO2 → Mo) with formation of intermediate phases of Mo4O11 during first step of reduction. However, the TPR results showed only one broad peak that correspond to all reduction step that was merge into one peak. It seem that, increasing the temperature cause the rapid reduction that correlated with thermodynamic consideration data that show the formation of metallic molybdenum is become feasible by increasing the temperature.

Reduction Behaviour of WO3 to W under Carbon Monoxide Atmosphere

2016 ◽  
Vol 840 ◽  
pp. 305-308
Author(s):  
Fairous Salleh ◽  
Tengku Shafazila Tengku Saharuddin ◽  
Alinda Samsuri ◽  
Rizafizah Othaman ◽  
Mohamed Wahab Mohamed Hisham ◽  
...  
Keyword(s):  
Carbon Monoxide ◽  
Temperature Programmed Reduction ◽  
X Ray Diffraction ◽  
Reduction Behavior ◽  
X Ray ◽  
Isothermal Reduction ◽  
Reduction Behaviour ◽  
Temperature Programmed ◽  
Metal Phases

The reduction behaviour of tungsten oxide has been studied by using temperature programmed reduction (TPR) and X-ray diffraction (XRD). The reduction behavior were examine by nonisothermal reduction up to 900 oC then continued with isothermal reduction at 900 oC for 45 min time under (40% v/v) carbon monoxide in nitrogen (CO in N2) atmosphere. The TPR signal clearly shows one peak attributed to formation of suboxide W18O49 (more) and WO2 (less) observed at 80 min. The reduction product was investigated by varying the holding reaction time. Based on the characterization of the reduction products by using XRD, it was found that, nonisothermal reduction of WO3 at temperature 900 oC partially converted to some W18O49 and WO2 phases. However, after increased the reaction holding time for 45 min, WO3 phases disappeared and converted to WO2 and W metal phases. It is obviously shows that by hold the reduction time could improve the reducibility of the sample oxide. Furthermore, it is suggested that reduction by using CO as reducing agent follows the consecutives steps WO3 → WO2.92 → W18O49 → WO2 → W.

Rate Constant Approximation with Cubic Splines for Kinetic Analysis of Temperature-Programmed Reduction Data

2019 ◽  
Vol 806 ◽  
pp. 87-92
Author(s):  
Arseniy Portnyagin ◽  
Alexey Golikov ◽  
Evgenii K. Papynov ◽  
Valentin Avramenko
Keyword(s):  
Kinetic Analysis ◽  
Rate Constant ◽  
Functional Materials ◽  
Preexponential Factor ◽  
Cubic Splines ◽  
Temperature Programmed Reduction ◽  
Heating Rates ◽  
Novel Approach ◽  
Analysis Technique ◽  
Temperature Programmed

Temperature-programmed reduction (TPR) is a widely used method for characterization of oxide-based catalysts, sorbents, and functional materials, but its results lack quantitative assessment. Here, we present a novel approach to kinetic analysis of the TPR that can be applied to a large variety of systems involving multiple limiting stages. Implementation of cubic splines to approximate rate constant vs. conversion dependencies obtained from several TPR curves recorded at different heating rates yields in a set of kinetic parameters (activation energy and preexponential factors) for all reduction stages. Relationship between preexponential factor of the first reduction stage and the specific surface area of the sample has been shown. Reduction of hematite has been studied to prove the performance of the developed kinetic analysis technique.

scholarly journals INFLUENCE OF CHROMIUM ON THE REDUCTION BEHAVIOR OF FERRIC OXIDE BY USING CARBON MONOXIDE: TEMPERATURE PROGRAMMED REDUCTION AND KINETIC STUDIES

2016 ◽  
Vol 20 (3) ◽  
pp. 531-538
Author(s):  
Tengku Shafazila Tengku Saharuddin ◽  
Alinda Samsuri ◽  
Fairous Salleh ◽  
Mohammad Bin Kassim ◽  
Rizafizah Othaman ◽  
...  
Keyword(s):  
Carbon Monoxide ◽  
Ferric Oxide ◽  
Kinetic Studies ◽  
Temperature Programmed Reduction ◽  
Reduction Behavior ◽  
Temperature Programmed

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%.

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