Coal liquefaction process streams characterization and evaluation: FT-IR methods for characterization of coal liquefaction products

Abstract

This study was designed to demonstrate the use of two FTIR techniques for the analysis of direct coal liquefaction process-derived materials. The two methods were quantitative FTIR analysis and themogravimetric (TG) analysis with FTIR analysis of evolved products (TG-FTIR). The quantitative FTIR analyses of both whole resids and THF-soluble resids provided quantitation of total hydrogen, aliphatic and aromatic hydrogen, total carbon, total oxygen, hydroxyl and etheric oxygen, and ash contents. The FTIR results were usually in agreement with values derived by other, more conventional methods. However, the accuracies of specific measurements, in comparisons with results from conventional methods, ranged from good to poor. The TG-FTIR method provided approximate analyses of coals and resids. The data provided included the time dependent evolution profiles of the volatile species and the elemental composition of the char. Reproducible data of gaseous species and pyrolysis tar yields for whole resid samples larger than 10 mg were obtainable. The yields and evolution profiles of certain volatiles (tar, CO, and methane) provided structural information on the samples. There were some experimental and interpretational difficulties associated with both techniques. Optimization of the curve-resolving routine for coal-liquefaction samples would improve the quantitative FTIR accuracy. Aerosol formation limited the fullmore » application of the TG-FTIR technique with the THF-soluble resid samples. At this time, further development of these analytical methods as process development tools will be required before their use for that purpose can be recommended. The use of FTIR as an on-line analytical technique for coal liquefaction process streams requires demonstration before it can be recommended; however, such a demonstration may be warranted.« less