Effects of ionic liquid concentration on coal low‐temperature oxidation

Abstract

In order to find out the optimal concentration of ionic liquid to lower the cost of inhibiting coal spontaneous combustion, effects of aliphatic hydrocarbons, hydrogen bonds, and some structural parameters of coal samples treated with low‐concentration ionic liquids were analyzed through Fourier‐transform infrared spectroscopy (FTIR) and temperature‐programmed experiments. Meanwhile, the changes of index gases in the heating process were observed by the temperature‐programmed method. The results show that the contents of aliphatic hydrocarbons in the treated coal samples decrease remarkably, so does the length of aliphatic chain CH2/CH3; besides, the amount of CO produced also decreases to some extent. When the mass concentration ratio is 1:10, HB‐tc, BB‐tc, AC‐tc, and BN‐tc can reduce the spatial structure and enhance the structural stability of aromatic clusters in coal. The CO concentrations of 1:2 HB‐tc and 1:10 AC‐tc are obviously lower than that of raw coal, indicating their better inhibitory effects. The inhibitory effect of HB‐tc decreases with the decrease in concentration. With the rise of temperature, the effect of concentration on the inhibition of CO production gradually weakens at 180°C and 200°C. AC‐tc achieves the optimum inhibitory effect near 1:10 mass concentration ratio.

Effect of Swelling with Ionic Liquid on the Molecular Structure and Pyrolysis Behavior of Hefeng Sub-bituminous Coal

“…This might have resulted from the fact that swelling destroys the side chains on the benzene ring, shortens part of the side chain, or reduces the substituent on the benzene ring. 23,45 3.5. FTIR Semiquantitative Analysis.…”

“…Also, the relative content of these functional groups increased, indicating that swelling with ionic liquid can destroy the macromolecular network structure of coal and increase the content of stable small aromatic compounds. 45 As listed in Table 2, four substitutions of benzene ring are primarily groups in HFC AC , with the relative content of 44.87%. While two and four substitutions of benzene ring are the main groups in swollen coals, and their relative contents are more than 65%.…”

“…The absorption peaks at 814 and 745 cm –1 belong to the out-of-plane bending vibration of the benzene ring, and the peak intensity of swollen coals is enhanced. This might have resulted from the fact that swelling destroys the side chains on the benzene ring, shortens part of the side chain, or reduces the substituent on the benzene ring. , …”

“…In addition, there are aromatic CC, asymmetric −CH 3 , −CH 2 , aromatic ring −CH 3 , and symmetric deformation −CH 3 in the range of 1300–1800 cm –1 . Also, the relative content of these functional groups increased, indicating that swelling with ionic liquid can destroy the macromolecular network structure of coal and increase the content of stable small aromatic compounds …”

Study on Failure Modes and Energy Evolution of Coal-Rock Combination under Cyclic Loading

“…Deformation and instability of coal and rock are accompanied by energy dissipation and release. erefore, it is of great significance to study the law of rock and coal energy evolution to explain the mechanical characteristics and failure mechanism of rock and coal under stress [50][51][52][53][54][55]. Under laboratory conditions, the energy evolution of coal and rock samples can be divided into four processes: energy input, energy accumulation, energy dissipation, and energy release.…”