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The relative abilities of mixtures of nonspecifically and specifically interacting solvents to swell a Utah Blind Canyon bituminous coal have been explored. The results are consistent with published reports of the efficacy of such mixed solvent systems but show sensitivity to the choice of specifically interacting solvent. The dynamics of swelling in such systems also serve to confirm the general nature of the process.

DME (Dimethyl Ether) has emerged as a clean alternative fuel for diesel. There are largely two methods for DME synthesis. A direct method of DME synthesis has been recently developed that has a more compact process than the indirect method. However, the direct method of DME synthesis has not yet been optimized at the face of its performance: yield and production rate of DME. In this study it is developed a simulation model through a kinetics model of the ASPEN plus simulator, performed to detect operating characteristics of DME direct synthesis. An overall DME synthesis process is referenced by experimental data of 3 ton/day (TPD) coal gasification pilot plant located at IAE in Korea. Supplying condition of DME synthesis model is equivalently set to 80 N/m 3 of syngas which is derived from a coal gasification plant. In the simulation it is assumed that the overall DME synthesis process proceeds with steadystate, vapor-solid reaction with DME catalyst. The physical properties of reactants are governed by Soave-RedlichKwong (SRK) EOS in this model. A reaction model of DME synthesis is considered that is applied with the LHHW (Langmuir-Hinshelwood Hougen Watson) equation as an adsorption-desorption model on the surface of the DME catalyst. After adjusting the kinetics of the DME synthesis reaction among reactants with experimental data, the kinetics of the governing reactions inner DME reactor are modified and coupled with the entire DME synthesis reaction. For validating simulation results of the DME synthesis model, the obtained simulation results are compared with experimental results: conversion ratio, DME yield and DME production rate. Then, a sensitivity analysis is performed by effects of operating variables such as pressure, temperature of the reactor, void fraction of catalyst and H 2 /CO ratio of supplied syngas with modified model. According to simulation results, optimum operating conditions of DME reactor are obtained in the range of 265-275 o C and 60 kg/cm 2 . And DME production rate has a maximum value in the range of 1-1.5 of H 2 /CO ratio in the syngas composition.

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Three different vacuum pyrolysis mass spectrometry techniques, viz., pyrolysis-field ionization mass spectrometry, thermogravimetry/low voltage electron ionization mass spectrometry, and Curie-point pyrolysis-low voltage electron ionization mass spectrometry, were used to analyze samples of Pittsburgh No. 8 coal obtained from the Argonne National Laboratory Premium Coal Sample Program. The primary objective was to assess the effects of differences in experimental techniques and conditions, e.g., with regard to heating rates, pyrolysis methods, and soft ionization procedures (FI vs low voltage EI) on the mass spectral patterns. A second objective was to further characterize and study the pyrolysis behavior of Pittsburgh No. 8 coal. The results indicate that the distribution and the type of the primary pyrolysis products are largely independent of marked differences in heating rate (10-2-104 K/s range) and sample size (2.5 X g range) as well as overall vacuum pyrolysis MS configurations and conditions used. All three vacuum pyrolysis MS techniques produce remarkably similar mass spectral patterns when analyzing Pittsburgh No. 8 coal. The results show that Pittsburgh No. 8 coal contains a significant amount of low temperature (<380 " C ) evolving "bitumen" consisting primarily of alkyl-substituted aromatic components. The bitumen evolution step is followed by partially overlapping "bulk pyrolysis" step characterized by the evolution of abundant hydroxy-and dihydroxy-substituted aromatic compounds, thought to be primarily derived from vitrinitic components. During the bitumen evolution step the average MW of the compounds increases with temperature while maintaining a relatively narrow distribution. By contrast, during the bulk pyrolysis step, the average MW tends to decrease while exhibiting a much broader distribution.to 5.0 X

A differential scanning calorimetry (DSC) study on the extraction residues of coals giving different extraction yields (which were prepared by changing the solvent composition of a carbon disulfide-N-methyl-2-pyrrolidinone mixed solvent extraction) was carried out. For the residues from Upper Freeport coal (APCS-1) with extraction yields lower than 30 wt % (daf), an endothermic peak similar to that given by the raw coal was observed around 350°C. This endothermic peak disappeared on the second and third scans, indicating that the peak is due to irreversible structural changes in coals. For the residues from the high extraction yield experiments, the peak was not observed up to 400°C, even during the first scan. The reason for these endothermic peaks was discussed from the relationship among the extraction, swelling, and structural changes of coals.