Solvent treatment of coals. 2. Effects on microporosity of extractions in the presence of ultrasonic energy

✍ Scribed by Myrna P. Klotzkin

• Publisher: Elsevier Science
• Year: 1988
• Tongue: English
• Weight: 651 KB
• Volume: 67
• Category: Article
• ISSN: 0016-2361
• DOI: 10.1016/0016-2361(88)90020-8

✦ Synopsis

Three bituminous coals were extracted with 12 different solvents and one solvent mixture in the presence of ultrasonic energy at ambient temperature. The effects of the extraction on the microporosity of the coals was determined by measuring the adsorption of CO, at 298 and 195 K and of N, at 77 K. It was found that with pyridine, ethylenediamine, THF, DMSO, methylpyrolidinone and DMF the ultrasonic energy enhanced the effectiveness of the solvents in increasing the total surface area of the coals as measured by CO2 at 298 K and also increased the rate of extraction. Only those solvents which satisfy the electron donor and acceptor number requirements of the donor-acceptor model of coal extraction were effective. The substantially greater increase in CO, surface areas of the coals when extracted in the presence of ultrasound indicate that more micropores are opened and widened and suggests that ultrasound weakens or breaks network-pore molecule bonds and facilitates extraction of pore molecules. Correlation between surface area increase and various solvent parameters was sought and excellent correlation was found with the ratio of donor number to acceptor number (DN/AN), a measure of the relative contribution of donor versus receptor sites on the coal surface, suggesting the use of DN/AN as a predictor of solvent effectiveness for bituminous coals.