Solubilisation of Victorian brown coal in 'distillable' DIMCARB
- Authors: Qi, Ying , Tikkoo, Tarun , Verheyen, Vincent , Ranganathan, Vijayaraghavan , MacFarlane, Douglas , Chaffee, Alan
- Date: 2013
- Type: Text , Conference paper
- Relation: 30th Annual International Pittsburgh Coal Conference 2013, PCC 2013
- Full Text: false
- Reviewed:
- Description: Victorian (Australia) brown coal is an abundant and cheap energy resource. There is intense interest in identifying new opportunities for its efficient and clean use, for example by solubilisation to produce high quality fuel or chemicals. Ionic liquids (ILs) have been applied increasingly in recent years to solubilize and recover cellulose, lignin and other components from complex biomass mixtures. Conventional ILs are not distillable and it can be difficult to separate the soluble product from the solvent. However, there is a group of ILs, produced by the association of a secondary amine and CO2 that are 'distillable' in that they will dissociate back to the respective amine and CO2 at moderate temperature to facilitate recovery. They can then be re-associated (recycled) by condensation at lower temperature. The simplest form of such ILs, DIMCARB, consists of dimethylamine associated with CO2 at a molar ratio of 2:1. DIMCARB has previously been found to be superior (in terms of solubility) to other ILs in this group for the extraction of a Victorian brown coal. In this study the extractability of a woody coal sample was compared with a run-of-mine (ROM) sample, both without pretreatment. The wet coal was mixed with DIMCARB at a dry mass ratio of 1 to 20 for 24 hours at room temperature. The soluble product was recovered by centrifuge and acid washed to remove residual DIMCARB. An extraction yield of 25% was achieved for the ROM sample, while for the woody coal the yield was only 10%. The recovered products were characterized by a range of chemical techniques including FTIR and Pyrolysis GC-MS. The lower solubility of the woody coal seems to be associated with a high degree of oxygen containing aromatic components. The nature of this difference and the selectivity of the extraction are discussed.
Ambient temperature solubilisation of brown coal in ammonium carbamate ionic liquids
- Authors: Qi, Ying , Verheyen, Vincent , Vijayaraghavan, Ranganathan , MacFarlane, Douglas , Chaffee, Alan
- Date: 2016
- Type: Text , Journal article
- Relation: Fuel Vol. 166, no. (2016), p. 106-115
- Full Text: false
- Reviewed:
- Description: Coal solubilisation is often a necessary step for the alternative utilisation of the cheap and abundant brown coal resources in the State of Victoria, Australia, such as producing high quality fuel or chemicals. A series of ionic liquids (ILs), ammonium carbamates, formed by the association of carbon dioxide (CO2) with low molecular weight secondary amines, were investigated as solvents for the solubilisation of Victorian brown coal. The ionic liquid was mixed with a Loy Yang coal at a mass ratio of 20 to 1 (dry basis) for 24 h at ambient temperature. The solubilisation yields of the coal using three such ILs from dimethyl-, diallyl- and dipropyl-amines, respectively, were between 18% and 23%. Repeated solubilisation of the coal with fresh solvent achieved higher yields, with the highest at 66% by the carbamate formed from dimethylamine (DIMCARB). The variations in chemical structure between the products were compared by elemental analysis and a variety of spectroscopic techniques (FTIR, Solid State 13C NMR and Py-GC-MS). The soluble products of the initial solubilisation were more aliphatic than their parent coal. The less polar ILs formed from diallyl- and dipropyl-amines (DACARB and DPCARB) appeared to be more selective for high molecular weight triterpenoids than DIMCARB. Subsequent treatment tended to dissolve more aromatic components. © 2015 Elsevier Ltd. All rights reserved.