ADVANCED LIQUEFACTION BY CATALYTIC REDUCTION OF LOW TEMPERATURE CROSSLINKING

LIQUEFACTION OF LOW RANK COALS OFFERS THE POTENTIAL OF HIGH OIL YIELDS. HOWEVER, BECAUSE OF THEIR SMALL AROMATIC RING CLUSTER SIZE, LOW RANK COALS ARE MORE DIFFICULT TO LIQUEFY IN THE FIRST (SOLUBILIZATION) STAGE UNDER CONDITIONS OPTIMIZED FOR BITUMINOUS COALS. IT IS LIKELY THAT CROSSLINKING REACTIONS ASSOCIATED WITH OXYGEN FUNCTIONAL GROUPS OCCUR BEFORE THE HOMOLYTIC CLEAVAGE REACTIONS. IF NOT CONTROLLED, THESE REACTIONS CAN LIMIT THE MAXIMUM CONVERSION OF COAL TO LIQUID. THE OBJECTIVE OF THIS PROJECT IS THE DEVELOPMENT OF A PRACTICAL CATALYTIC PRELIQUEFACTION STEP TO CONTROL LOW TEMPERATURE CROSSLINKING EVENTS FOR LOW RANK COALS. THE PROJECT PLAN IS BASED ON THE CONCLUSION THAT THE PREVIOUSLY REPORTED IMPROVED LIQUEFACTION RESULTS WERE DUE TO THE CATALYTIC REDUCTION OF THIS CROSSLINKING EVENT. BEFORE A PRACTICAL PROCESS CAN BE DEVELOPED, THE FOLLOWING MUST BE ACHIEVED: (1) A THOROUGH UNDERSTANDING OF THE CROSSLINKING REACTIONS AND THEIR MODIFICATIONS BY THE PRESENCE OF A CATALYST AND SOLVENT; (2) THE OPTIMIZATION OF THE CATALYSTS AND SOLVENT FOR A PRACTICAL CATALYTIC PRELIQUEFACTION STEP; AND (3) THE DEVELOPMENT OF A PROCESS BASED ON THE OPTIMIZED CATALYTIC PRELIQUEFACTION STEP. SIGNIFICANT PROGRESS HAS ALREADY BEEN MADE TOWARD ACHIEVING THE FIRST OBJECTIVE. THUS, PHASE I OF THE PROJECT WILL FOCUS ON THE SECOND OBJECTIVE. THIS WORK USES AN ADVANCED TUBING BOMB APPARATUS WITH ON-LINE GAS ANALYSIS TO CONDUCT AN EXPERIMENTAL STUDY OF A LOW RANK COAL AND MODEL COMPOUNDS. THE STUDY USES SEVERAL CATALYST/SOLVENT COMBINATIONS TO IDENTIFY AN OPTIMAL CATALYST/SOLVENT COMBINATION FOR A SINGLE COAL. THESE EXPERIMENTS FORM THE BASIS FOR QUANTITATIVE MODELING OF THE CHEMICAL REACTIONS THAT ARE IMPORTANT FOR ACHIEVING THE THIRD OBJECTIVE, TO BE ACCOMPLISHED IN PHASE II. THE PHASE II PROJECT WILL USE A CONTINUOUS FLOW EXPERIMENT TO VERIFY THE PROCESS CONCEPTS. THE PHASE II PROJECT WILL ALSO EXTEND THE RESEARCH EFFORT TO OTHER LOW RANK COALS AND PROCESS-DERIVED SOLVENTS.