Improvement in coal liquefaction solvent quality by dewaxing

• Main Authors: Winschel, R.A., Robbins, G.A., Burke, F.P.
• Language: unknown
• Published: 2020
• Subjects: 01 COAL; LIGNITE; AND PEAT; COAL LIQUEFACTION; SOLVENTS; DEWAXING; AUTOCLAVES; CHEMICAL COMPOSITION; GAS CHROMATOGRAPHY; KETONES; NMR SPECTRA; PARAFFIN; UREA; YIELDS; ALKANES; AMIDES; CARBONIC ACID DERIVATIVES; CHROMATOGRAPHY; HYDROCARBONS; LIQUEFACTION; ORGANIC COMPOUNDS; ORGANIC NITROGEN COMPOUNDS; OTHER ORGANIC COMPOUNDS; SEPARATION PROCESSES; SPECTRA; THERMOCHEMICAL PROCESSES; WAXES; Carbonic acid
• Online Access: http://www.osti.gov/servlets/purl/6274014; https://www.osti.gov/biblio/6274014; https://doi.org/10.1016/0016-2361%2887%2990275-4; https://doi.org/10.1016/0016-2361(87)90275-4

Recycle oils from the Integrated Two-Stage Liquefaction (ITSL), H-Coal and Solvent Refined Coal (SRC) processes were dewaxed by variants of commercial dewaxing processes yielding up to 47 wt % ''wax''. Dewaxing methods used include the ketone and the urea adduction techniques. The clean waxes are reasonably pure paraffins. The dewaxed oils were substantially better coal liquefaction solvents than the original (non-dewaxed) oils in batch liquefaction tests. For example, in one case, dewaxing improved the conversion of a standard coal to tetrahydrofuran solubles at standard reaction conditions from 71% with the original oil to 87% with dewaxed oil. These data provide a direct indication of the inimical effect of paraffin components on solvent quality. The impact of solvent quality is particularly relevant to two-stage liquefaction, in which thermal first-stage reactions proceed in a recycle solvent. In addition, these results indicate the technical feasibility of dewaxing coal liquefaction recycle oils by commercially available technology to improve solvent quality and to produce a useful by-product. Dewaxing could be applied to any liquefaction process that uses a deashed (preferably distillate) recycle stream. 14 refs., 2 figs., 3 tabs.