Effect of Experimental Conditions on Parameters Derived from Micro Calorimeter Measurements of Coal Low-Temperature Oxidation

2013 ◽  
Vol 316-317 ◽  
pp. 850-853
Author(s):  
Xiao Xing Zhong ◽  
Yun Chen ◽  
Guo Lan Dou ◽  
De Ming Wang
Keyword(s):  
Low Temperature ◽  
Heat Release ◽  
Coal Sample ◽  
Gas Flow ◽  
Low Temperature Oxidation ◽  
Experimental Conditions ◽  
Sample Mass ◽  
Temperature Oxidation ◽  
Initial Heat ◽  
Micro Calorimeter

C80 micro calorimeter was applied to investigate the initial heat release temperature and heat output at low-temperature oxidation process of Kabuliang anthracite coal under the experimental conditions of different coal sample mass, different temperature rising rates and different gas flow, and analyzed the effect of experimental conditions on test results. The results indicate that the coal sample mass and temperature rising rate affect measurement results, while there is no effect of gas flow. Under the same experimental condition, a higher temperature rising rate leads to a higher initial heat release temperature and less output of heat; The initial heat release temperature shows the trend of increase after decrease with the increase of coal sample mass. So, when micro calorimeter is used to investigate the coal low-temperature oxidation process, the experiments under the conditions of appropriate coal sample mass and the lower temperature rising rate can obtain more accurate test parameters.

Evaluation of heat release caused by low-temperature oxidation of heavy oil and its SARA fractions under isothermal conditions

2020 ◽  
Vol 690 ◽  
pp. 178690
Author(s):  
Shuai Zhao ◽  
Wanfen Pu ◽  
Mikhail A. Varfolomeev ◽  
Hao Ren ◽  
Ai Kenjiang ◽  
...  
Keyword(s):  
Low Temperature ◽  
Heat Release ◽  
Heavy Oil ◽  
Low Temperature Oxidation ◽  
Temperature Oxidation ◽  
Isothermal Conditions ◽  
Sara Fractions

The Mechanism of the Low-Temperature Oxidation of Coal by O2: Observation and Separation of Simultaneous Reactions Using In Situ FT-IR Difference Spectroscopy

1987 ◽  
Vol 41 (1) ◽  
pp. 50-63 ◽  
Author(s):  
Jon S. Gethner
Keyword(s):  
Low Temperature ◽  
Reactive Species ◽  
Spontaneous Ignition ◽  
Difference Spectroscopy ◽  
Low Temperature Oxidation ◽  
Experimental Conditions ◽  
Temperature Oxidation ◽  
Thin Sections ◽  
Ft Ir

Coal is complex, predominantly organic-containing porous solid which is important both as an energy and a chemical source material. The physical and chemical properties of most coals are extremely sensitive to air oxidation. There is no generally accepted mechanism for the oxidation process, in spite of past interest. Using in situ FT-IR difference spectroscopy of 0.4 μm thin sections of coal, we have examined the mechanism of the low-temperature oxidation of Illinois No. 6 bituminous coal by O2. The overall oxidation with O2 is found to be comprised of three separate chemical reactions. Two of the reactions involve O2 addition to reactive species in the coal. One is predominant at temperatures close to or slightly above room temperature and apparently involves the reversible binding of O2 to a free radical site, followed by reaction. The other oxidation is predominant by 100°C and proceeds by the formation and subsequent decomposition of hydroperoxides. The third reaction is a thermolysis which is important at temperatures between 25°C and 100°C and is competitive with the lower-temperature oxidation. It results in a partial decarbonylation and decarboxylation of the coal. Since three separate reactions contribute to the overall oxidation, the chemical and physical changes resulting from oxidation are dependent upon the oxidation conditions. Control of experimental conditions is critical in order for one to obtain reproducible results. Some of the possible implications of these results on the technologically important process of spontaneous ignition of coal are discussed. Results of previous oxidation studies are discussed in view of the present results. The large variations reported in oxidation studies are likely to be the consequence of ill-defined or poorly controlled experiments. We interpret the correlation between the present study and number of other studies to indicate that oxidation chemistry is the same in most coals, with the principal differences between coals being due to the different relative proportions of the reactive species in the starting coal.

scholarly journals Influence of Co-Precipitation Agent on the Structure, Texture and Catalytic Activity of Au-CeO2 Catalysts in Low-Temperature Oxidation of Benzyl Alcohol

Catalysts ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 641
Author(s):  
Lukasz Wolski ◽  
Grzegorz Nowaczyk ◽  
Stefan Jurga ◽  
Maria Ziolek
Keyword(s):  
Gold Nanoparticles ◽  
Catalytic Activity ◽  
Low Temperature ◽  
Benzyl Alcohol ◽  
Low Temperature Oxidation ◽  
Temperature Oxidation ◽  
Oxidation Of Benzyl Alcohol ◽  
Key Factor ◽  
Au Particle Size ◽  
Co Precipitation

The aim of the study was to establish the influence of a co-precipitation agent (i.e., NaOH–immediate precipitation; hexamethylenetetramine/urea–gradual precipitation and growth of nanostructures) on the properties and catalytic activity of as-synthesized Au-CeO2 nanocomposites. All catalysts were fully characterized with the use of XRD, nitrogen physisorption, ICP-OES, SEM, HR-TEM, UV-vis, XPS, and tested in low-temperature oxidation of benzyl alcohol as a model oxidation reaction. The results obtained in this study indicated that the type of co-precipitation agent has a significant impact on the growth of gold species. Immediate co-precipitation of Au-CeO2 nanostructures with the use of NaOH allowed obtainment of considerably smaller and more homogeneous in size gold nanoparticles than those formed by gradual co-precipitation and growth of Au-CeO2 nanostructures in the presence of hexamethylenetetramine or urea. In the catalytic tests, it was established that the key factor promoting high activity in low-temperature oxidation of benzyl alcohol was size of gold nanoparticles. The highest conversion of the alcohol was observed for the catalyst containing the smallest Au particle size (i.e., Au-CeO2 nanocomposite prepared with the use of NaOH as a co-precipitation agent).

Sign in / Sign up

Export Citation Format

Share Document