Inhibitory Effect of Phosphonium-Based Ionic Liquids on Coal Oxidation

Weiqing Zhan*, Shuguang Jiang, Christopher Hardacre, Peter Goodrich, Kai Wang, Zhengyan Wu, Hao Shao

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

25 Citations (Scopus)

Abstract

To develop a chemical inhibitor that can efficiently suppress coal oxidation, nine tetraalkylphosphonium-based ionic liquids (ILs) and one imidazolium-based IL [1-allyl-3-methylimidazolium chloride ([AMIm]Cl)] were examined as additives. These ILs were used to treat and investigate the inhibitory effect on the oxidation activity and the structure of lignite coal. Characterization using thermogravimetric analysis showed that phosphonium-based ILs are able to inhibit coal oxidation up to 400 degrees C with the tributylethylphosphonium diethylphosphate ([P-4,P-4,P-4,P-2][DEP]) found to be the most effective. In contrast to the tetraalkylphosphonium-based ILs, inhibition using [AMIm]Cl was only found to be effective at temperatures below 250 degrees C, indicating that the tetraallcylphosphonium-based ILs may be more suitable for the future application of suppressing coal spontaneous combustion over a wide range of temperatures. Fourier transform infrared spectroscopic data showed that the various functional groups change in the coal following IL treatment, which are a decrease in the minerals and hydrogen bonds in all treated coals, while decreased aliphatic hydrocarbon and increased carbonyl bonds only appeared in some samples. During the oxidation of coal, the decomposition of aliphatic hydrocarbon groups is inhibited and the formation of carbonyl groups is delayed, so that the evolved gas concentration decreased, as shown by the temperature-programmed oxidation-mass spectrometry results. The deployment of the [P-4,P-4,P-4,P-2][ DEP] and tributylmethylphosphonium methylsulfate Its as additives also show good inhibitory effect on coal oxidation over the temperature range studied, and a relatively stronger interaction between [P-4,P-4,P-4,P-2] [DEP] and coal is demonstrated by the additive model.

Original languageEnglish
Pages (from-to)4333-4341
Number of pages9
JournalEnergy & Fuels
Volume28
Issue number7
DOIs
Publication statusPublished - 19 Jun 2014

Keywords

  • LOW-TEMPERATURE OXIDATION
  • LIQUEFACTION RESIDUE
  • 1-ALLYL-3-METHYLIMIDAZOLIUM CHLORIDE
  • FUNCTIONAL-GROUPS
  • ROOM-TEMPERATURE
  • BITUMINOUS COAL
  • FT-IR
  • EXTRACTION
  • ASPHALTENES
  • DISPERSION

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