Thermally Initiated Carbon-Carbon Bond Cleavage Reactions Occurring During Coal Gasification. Final Report April 1985-June 1988

摘要

Illinois No. 6 high volatile bituminous coals were modified by incorporating selected molecules via base-catalyzed alkylation reactions. The modified coals were pyrolyzed on a wire-screen reactor at 700 degrees - 900 degrees C in helium at 0.02 mPa and the reaction products separated into char, tar and gas. The product distributions showed that char formation is suppressed and tar formation is enhanced by the organic fragments. The results strongly suggest that hydrogen atom abstraction reactions are accompanied by beta-scission reactions to form ethene, propene, butene, and pentene and butadiene. In addition, a rearrangement reaction involving a six-membered ring transition state is invoked to explain the formation of propane and propene. In the pyrolysis of arylalkanes, the radicals formed in hydrogen atom donation reactions undergo an array of beta-scission reactions to form one, two and three carbon atom compounds. Surprisingly, ispso demethylation is a slow reaction in the environment of the coal molecule under these conditions. Finally, in the pyrolysis of the labeled ttetralin derivatives, generally, ring contraction coupled with demethylation gives methane. The distribution of labels in the gas suggests that retrocyclo addition reactions play a role in the product formation of ethylene from tetralin-like structures in the coal molecule.