Examination of Coal Solubility and Fragmentation with Various Ionic Liquids
Open Access
- Author:
- Pulati, Nuerxida
- Graduate Program:
- Materials Science and Engineering
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- September 07, 2011
- Committee Members:
- Professor Paul C Painter, Thesis Advisor/Co-Advisor
Paul C Painter, Thesis Advisor/Co-Advisor - Keywords:
- coal dissolution
coal
ionic liquid
coal fragmentation - Abstract:
- The organic component of coal is heterogeneous and often has a complicated network structure. When exposed to certain solvents, swelling and partial dissolution often occurs. However, due to the structural complexity of coal, an understanding of the interaction between solvents and coal remains challenging. In this thesis the effect of a new class of solvents, ionic liquids are investigated. It was reported that ionic liquids dissolve cellulose, previously considered insoluble in all solvents. In the work described in this thesis, ionic liquids were used as a “solvent” to contact coal under different condition to observe if enhanced solubility also occurs. Several ionic liquids were contacted with coals and ionic liquid mixtures were heated up to 100°C overnight and cooled back to room temperature. Ionic liquid containing 1-butyl-3- methylimidazaolium cation with different types of anions were studied; Ionic liquids containing [Cl]- anions formed a black dispersion/gel upon heating up the mixture to 100°C and a black slurry remained after cooled to room temperature. Long alkyl chain and benzyl chain substituted imidazolium ionic liquids produced, a viscous black slurry/ gel formed when coal/ionic liquid mixtures were heated up to 100°C and the mixture remained a viscous gel upon cooling. Optical micrographs showed the coal had fractured to smaller size particles. Other ionic liquids, such as [bmim][CF3SO3], [bmim][BF4], were also found to disperse or fragment coal particles when heat up to 250°C or 300°C when combined with tetralin and hydrogen under pressure. Higher yields of pyridine soluble materials were obtained after coal was treated with [bmim][CF3SO3]. FTIR-DRIFT characterized the pyridine insoluble residue. With the spectra mainly contain mineral matter components, a good indication that extensive of hydrogenation of coal can take place under these lower temperatures by adding ionic liquid, [bmim][CF3SO3]. The coal/ionic liquid dispersion also showed enhanced solubility when simply stirred in NMP at room temperature compared to samples without ionic liquid additions. The extent of swelling and dispersing of coal with certain ionic liquids is related to intermolecular interactions. Ionic liquids can engage in a wide range of intermolecular interactions, hydrogen bonding, ion-dipole and dipole-dipole interactions, π-cation interactions, etc. Under quantification of these contributions would aid elucidation of mechanics for this coal/ionic liquid dissolution/dispersion system.