Coking coal was extracted with tetrahydrofuran solvent using ultrasonic and microwave-assisted method at 50°C and atmospheric pressure. Wettability of raw coal and its residue (residual coal) was tested with capillary penetration method. The raw and residual coals were studied by Fourier transform infrared spectroscopy (FTIR) with curve-fitting analysis. The variation of main surface functional groups of coking coal before and after extraction and its effect on wettability were analyzed. The results were obtained as the following: after extraction with tetrahydrofuran, hydroxyl, ether oxygen, and carbonyl in the coal structure were dissolved, the content of hydrophilic functional groups reduced, and then the hydrophobicity of coal enhanced. At the same time, part of aliphatic hydrocarbon dissolved, the length of aliphatic chains (I2) decreased from 3.961 of raw coal to 3.636 of residual coal, the length of aliphatic chains became shorter, aliphatic CH2 side-chains decreased and aliphatic CH3 side-chains increased, and hydrophobic functional groups content increased. In the aromatic structure, four hydrogens per ring increased and two, three, and five hydrogens per ring decreased. Reduction of substitution functional groups and aliphatic hydrocarbon decreased with the side-chains breakage produce more active sites, which increases the degree of condensation of the aromatic ring (I3). The combined action of the decrease of the hydrophilic functional groups and the increase of the hydrophobic functional groups made the wettability of the coking coal become weak.
Metallic platinum nanocatalysts play a key role in the liquid‐phase selective hydrogenation of substrates with more than one unsaturated bond. However, the commonly applied explanation for the effects of different electronic and geometric properties of catalysts on reactions remains of a heuristic nature due to the difficulties involved in preparing catalysts with precise structure. In this work, we have directly loaded pre‐synthesized metallic platinum nanoparticles onto well‐structured ZnO nanorods and then subjected them to thermal treatment in a reductive atmosphere for different temperatures. The effects of the different electronic and geometric properties of the catalysts on the selective reduction of 3‐nitrostyrene to 3‐vinylaniline as a model reaction have been rigorously explored through an analysis of the catalyst structures and the activity and selectivity profiles. Both the electron transfer from zinc to platinum and the decreased platinum surface density as a result of the formation of PtZn intermetallic compounds are key factors for improving the selectivity for the desired 3‐vinylaniline. Azobenzene was detected in the reaction with all the Pt/ZnO catalysts after 10–90 min, which indicates that the reaction follows a condensation mechanism.
Introducing atmosphere in transmission electron microscope enables to directly observe the structural features of catalyst under working conditions. It offers the possibility to study the microstructural evolution and correlate real structures with catalytic properties at nano‐ or atomic‐scale during catalysis. However, the damages to catalyst derived from the high energy electron‐beam irradiation cannot be ignored and may lead to ambiguous conclusions, as the interaction between reactive gas molecules and active structures is only desired. Herein, the α‐Ga2O3 supported Pd catalyst was selected as a model to evaluate the potential effect of electron‐beam on the surface and interface structures, which directly affect the catalytic performance, at varied atmospheres, elevated temperatures and increased electron dose rate in ambient pressure. The results indicate that the supported Pd nanoparticles could be encapsulated by GaOx layer when the imaging electron dose rate is higher than 100 e/Å2s under reduction and oxidizing atmosphere. Either increasing the electron dose rate or elevating the temperature exacerbates the irradiation damage to α‐Ga2O3 support. This work was expected to evaluate the effect of electron dose rate to supported catalysts under chemical environments, and provide guidance for the investigation of in‐situ transmission electron microscopy under ambient pressure.
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