Study of the Microstructure of Coal at Different Temperatures and Quantitative Fractal Characterization.

In order to understand the influence of underground coal fires on coal fractures and pores, mercury intrusion porosimetry (MIP) and scanning electron microscopy (SEM) are combined to study the development of coal pore and fracture under high-temperature treatment and calculate the fractal dimension to analyze the relationship between the development of coal pore and fracture and the fractal dimension. The results show that the volume of pores and fractures of the coal sample (C200) treated at 200 °C (0.1715 mL/g) is greater than that of the coal sample (C400) treated at 400 °C (0.1209 mL/g), and both are greater than the original coal sample (RC) (0.1135 mL/g). The volume increase is mainly due to mesopores and macropores, and the proportions of mesopores and macropores in C200 were 70.15 and 59.97% in C400. The MIP fractal dimension shows a decreasing trend with the increase of temperature, and the connectivity of coal samples improved with the increase of temperature. The changes in volume and three-dimensional fractal dimension of C200 and C400 showed the opposite trend and are related to the different stress of coal matrix at different temperatures. The experimental SEM images confirm that the connectivity of coal fractures and pores improves with the increase of temperature. Based on the SEM experiment, the larger the fractal dimension, the more complex the surface is. The SEM surface fractal dimensions indicate that the surface fractal dimension of C200 is the smallest and that of C400 is the largest, which is consistent with the observations made by SEM. The combination of the two fractal dimensions is used to characterize the self-similarity of coal using the fractal dimension difference. When the temperature increased to 200 °C, the unordered expansion of the coal sample resulted in the largest fractal dimension difference and the lowest self-similarity. When heated to 400 °C, the fractal dimension difference of the coal sample is the smallest, and the microstructure of coal shows a regular groove-like development.

[Denitration mechanism of monoclinic-phase nano zirconium oxide-based catalysts].

The MnO(x)-CeO2/m-ZrO2 catalyst was prepared by impregnation with nano monoclinic-phase zirconium (m-ZrO2) as the supporter. The influence of active component and reaction temperature on the denitration performance of the catalyst was investigated, while the surface properties of the catalyst and the denitration mechanism were discussed. The denitration efficiency was improved as the active component increased and the reaction temperature rose. The denitration efficiency of 2.5% MnO(x)-CeO2/m-ZrO2 catalyst at 110 degrees C was 55.5% while that of 15% MnO(x)-CeO2/m-ZrO2 catalyst was 93.5%. The results of XRD, SEM, BET and H2-TPR showed that the surface structure of the loaded catalyst was beneficial for denitration and oxidation-reduction. NH3-TPD test demonstrated that NH3 was adsorbed at the Lewis acid sites and Brönsted acid sites on the surface of catalysts. Intermediate products NH2NO and NH4NO were generated from a series of reactions between NO and NH3 and finally transformed into N2 and H2O. Most of the denitration process happened at Lewis acid sites.

Copper-catalyzed one-pot trifluoromethylation/aryl migration/carbonyl formation with homopropargylic alcohols.

A novel copper-catalyzed one-pot functionalization of homopropargylic alcohols that involves trifluoromethylation, aryl migration, and formation of a carbonyl moiety has been developed. This reaction constitutes the first direct conversion of homopropargylic alcohols into CF3-containing 3-butenal or 3-buten-1-one derivatives in a regioselective manner. Mechanistic studies indicate that the 1,4-aryl migration proceeds through a radical pathway.