Mild coal pretreatment to improve liquefaction reactivity. Final technical report, September 1990--February 1994

One of 5 reports in the title: Mild Coal Pretreatment to Improve Liquefaction Reactivity Progress Report available on this site.

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Recent research efforts in direct coal liquefaction are focused on lowering the level of reaction severity, identification and determination of the causes of retrogressive reactions, and improving the economics of the process. Ambient pretreatment of coals using methanol and a trace amount of hydrochloric acid was extensively studied in connection with low severity coal liquefaction. Ambient pretreatment of eight Argonne coals using methanol/HCl improved THF-soluble conversions 24.5 wt % (maf basis) for Wyodak subbituminous coal and 28.4 wt % for Beulah-Zap lignite with an average increase of 14.9 wt % for the eight Argonne coals at 623 K (350{degrees}C) reaction … continued below

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321 p.

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Miller, R. L. & Shams, K. G. July 1994.

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Recent research efforts in direct coal liquefaction are focused on lowering the level of reaction severity, identification and determination of the causes of retrogressive reactions, and improving the economics of the process. Ambient pretreatment of coals using methanol and a trace amount of hydrochloric acid was extensively studied in connection with low severity coal liquefaction. Ambient pretreatment of eight Argonne coals using methanol/HCl improved THF-soluble conversions 24.5 wt % (maf basis) for Wyodak subbituminous coal and 28.4 wt % for Beulah-Zap lignite with an average increase of 14.9 wt % for the eight Argonne coals at 623 K (350{degrees}C) reaction temperature and 30 minutes reaction time. Optimal pretreatment conditions were determined using Wyodak and Illinois No. 6 coals. Acid concentration was the most important pretreatment variable studied; liquefaction reactivity increased with increasing acid concentration up to 2 vol %. The FTIR spectra of treated and untreated Wyodak coal samples demonstrated formation of carboxylic functional groups during pretreatment, a result of divalent (Ca, Mg) cationic bridge destruction. The extent of liquefaction reactivity directly correlated with the amount of calcium removed during pretreatment, and results from calcium ``addback`` experiments supported the observation that calcium adversely affected coal reactivity at low severity reaction conditions. Model compound studies using benzyl phenyl ether demonstrated that calcium cations catalyzed retrogressive reactions, inhibited hydrogenation reactions at low severity reaction conditions, and were more active at higher reaction temperatures. Based on kinetic data, mechanisms for hydrogenation-based inhibition and base-catalyzed retrogressive reactions are proposed. The base-catalyzed retrogressive reactions are shown to occur via a hydrogen abstraction mechanism where hydrogenation inhibition reactions are shown to take place via a surface quenching mechanism.

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321 p.

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OSTI as DE94014510; Paper copy available at OSTI: phone, 865-576-8401, or email, reports@adonis.osti.gov

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  • July 1994

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  • Nov. 28, 2018, 2:33 p.m.

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  • Dec. 4, 2024, 5:01 a.m.

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Miller, R. L. & Shams, K. G. Mild coal pretreatment to improve liquefaction reactivity. Final technical report, September 1990--February 1994, report, July 1994; Golden, Colorado. (https://digital.library.unt.edu/ark:/67531/metadc1341380/: accessed April 13, 2026), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.

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