Treatment of coal to increase yields and improve physical

Abstract

Treatment of weakly acidic protons in coal by oxygen-alkylation or oxygen-acylation employing a phase transfer reaction under mild conditions increases the yield, lowers the viscosity and boiling ranges of coal liquefaction distillates and renders these coal liquids more compatible with petroleum liquids. The process also improves the compatibility with petroleum liquids of the coal liquefaction bottoms and their solubility in common organic solvents. The phase transfer reaction chemically alters phenolic and carboxylic functional substituents. These two very polar functional groups are converted to relatively non-polar ethers and esters, respectively. The O-alkylation or O-acylation is carried out in a binary liquid phase solution (organic and water phases with a solid phase suspended in the medium). A quaternary ammonium or phosphonium salt is reacted with alkali or alkaline earth base (caustic) to produce the corresponding quaternary ammonium or phosphonium base (an example of a phase transfer reagent). This quaternary base is non-nucleophilic and readily removes the phenolic and carboxylic protons, but does little else to the coal structures. After the removal of the weakly acidic protons by the quaternary base, the phenoxides and carboxylates which are produced then under O-alkylation or O-acylation. The alkylating or acylating agent comprises a carbon-bearing functional group and a displaceable leaving group.