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Coal and oil shale are often mined and utilized together, and mixed dust is easily formed in these processes. In order to ensure safe production in these processes, the explosion characteristics of mixed dust were studied. Using a Godbert-Greenwold (G-G) Furnace experimental device, Hartmann tube experimental device, and 20 L explosion vessel, the oil shale and coal mixed dust ignition sensitivity experiment, flame propagation experiment, and explosion characteristics experiment were carried out. The minimum ignition temperature (MIT), minimum ignition energy (MIE), maximum explosion pressure (Pmax), maximum rate of pressure rise ((dp/dt)max), and explosibility index (KSt) parameters and the flame propagation behavior of the mixed dust were analyzed in detail. A scanning electron microscope (SEM) analysis of the coal and oil shale dust before and after the explosion was carried out to study the changes in the microscopic morphology of the dust particles. The results show that due to the oil shale having a high volatile content and low moisture content, in the mixture, the greater the percentage of oil shale, the more likely the dust cloud is to be ignited and the faster the explosion flame is propagated; the greater the percentage of oil shale, the greater the (dP/dt)max and KSt will be and, under a high dust concentration, a greater Pmax will be produced. During explosion, coal dust will experience particle pyrolysis and the gas phase combustion of the volatile matter, followed by solid phase combustion of coal char, whereas oil shale dust will only experience particle pyrolysis and the gas phase combustion of the volatile matter.

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Two novel metal-free phthalocyanines have been designed and synthesized, namely tetra{[1H-benzo(d)imidazol-2-yl]thiol}phthalocyanine (TBIT-Pc) and tetra{[benzo(d)thiazol-2-yl]thiol}phthalocyanine (TBTT-Pc). These two compounds showed similar structures, while imidazolyl-NH in the substitutes of TBIT-Pc could form more hydrogen bonds. TBIT-Pc and TBTT-Pc were fully characterized by elemental analysis, 1 H NMR, MALDI-TOF MS, FT-IR and the UV-Vis absorption spectrum. The self-assembly properties of TBIT-Pc and TBTT-Pc were comparatively studied. TBIT-Pc and TBTT-Pc were present as monomers in DMF in the concentration range of 9.04-20.3 mM. Depending mainly on the intermolecular hydrogen bonding (N-HÁ Á ÁN) between benzimidazole substitutes, ''head-to-tail'' J-aggregates of TBIT-Pc were formed in DMSO, while there was no aggregation of TBTT-Pc in the same solvent. ''Face-to-face'' H-aggregates of TBIT-Pc and TBTT-Pc were formed with the addition of water to the solutions of DMSO, and the degree of aggregation increased with the introduction of H-bonds (N-HÁ Á ÁN) in the benzimidazole substitutes of TBIT-Pc. The atomic force microscope (AFM) image and dynamic light scattering (DLS) displayed the formation of well-defined nanoparticles with a diameter of ca. 30 AE 15 nm with J-type aggregation of TBIT-Pc. And the dendritic nanostructures with H-aggregates of TBIT-Pc and TBTT-Pc with different size were observed from transmission electron microscopy (TEM) images. The possible mechanism of the effect of H-bonds on the formation of J-aggregates of TBIT-Pc and the H-aggregation of TBIT-Pc and TBTT-Pc was also discussed. In the formation process of aggregates, H-bonds and p-p interaction may be the dominant factors. In addition, the nanostructures fabricated from TBIT-Pc and TBTT-Pc showed good semiconducting properties revealed by current-voltage measurements.Scheme 1 Synthetic route of novel tetra{[1H-benzo(d)imidazol-2-yl]thiol}phthalocyanine (TBIT-Pc, 6) and tetra{[benzo(d)thiazol-2-yl]thiol}phthalocyanine (TBTT-Pc, 7).

A Ca(H2PO4)2/RM composite powder suppressant with core–shell structure was prepared with modified red mud (RM) as the carrier and Ca(H2PO4)2 as the loaded particles, using a solvent–antisolvent process, in an attempt to suppress aluminum dust explosion more effectively. The suppression effects of the Ca(H2PO4)2/RM composite powder suppressant for aluminum dust flame propagation and for explosion overpressure were tested in a vertical glass tube test apparatus and a 20 L explosion vessel. The results show that the Ca(H2PO4)2/RM composite powder suppressant was more effective in suppressing aluminum dust flame propagation and explosion overpressure than either Ca(H2PO4)2 or RM powder alone. Finally, the suppression mechanism of the Ca(H2PO4)2/RM composite powder suppressant was analyzed. On the one hand, a large amount of burning heat was absorbed through the decomposition of Ca(H2PO4)2 and the melting phase transformation of the decomposition product; on the other hand, the strong isolation provided by the RM helped limit flame propagation. The strong adsorptivity of RM allowed this material to adsorb the radicals from the explosion reaction perfectly.

A series of dicationic ionic liquids were successfully prepared, and they were first used to convert the n-pentane into iso-alkanes as an environmentally safe way to improve the octane number of gasoline. As a novel and green catalyst, the dicationic ionic liquid [tetramethylethylenediamine­(EtBr)2]-AlCl3 ([TMEDA­(EtBr)2]-AlCl3) exhibits higher catalytic performance in n-pentane isomerization than the traditional monocationic ionic liquid [1-butyl-3-methylimidazolium]­Cl-AlCl3 ([BMIM]­Cl-AlCl3). And for the n-pentane isomerization reaction catalyzed by [TMEDA­(EtBr)2]-AlCl3, the optimal reaction temperature, reaction time, and mass ratio of catalyst to oil were proven to be 100 °C, 3 h, and 1:1, respectively. For dicationic ionic liquid [TMEDA­(EtBr)2]-AlCl3, the acid strength of it increases steadily with the increase of AlCl3 mole fractions. And the initiator is conducive to increasing n-pentane conversion, improving the yield of i-C5 and i-C6, and inhibiting the C4 component. Additionally, as the length of substitute alkyl groups of cationic structures in dicationic ionic liquids increases, the catalytic conversion of n-pentane and the yield of iso-alkanes decrease constantly. For novel dicationic ILs, the moderate rising of temperature facilitates improving the catalytic performance of n-pentane isomerization, in particular, for the ionic liquids with higher melting points. Moreover, the mechanism of n-pentane isomerization catalyzed by dicationic ionic liquid was studied, which revealed the reason that [TMEDA­(EtBr)2]-AlCl3 IL has better catalytic performance than monocationic ionic liquid and other dicationic ILs.