VARIATION OF TEMPERATURE EFFECT WITH HYDROGEN SUPPLY IN NON-CATALYTIC COAL LIQUEFACTION

Abstract

ABSTRACT A Spanish subbituminous coal was subjected to non-catalytic liquefaction with tetralin in a 250 ml stirred autoclave. The operating conditions used were: one hour reaction time, 17 MPa operating pressure and 400 r.p.m, stirring speed. The liquefaction products were fractionated into oils, asphaltenes, preasphaltenes and solid residue by a solvent extraction technique using pentane, toluene and THF as extractive solvents. It was found that the influence of temperature on coal liquefaction yields and product distributions varies with the amount of donatable hydrogen. Total coal conversion increases with temperature, when very high tetralin/coal ratios are used On the contrary, when 1/1 ratio is used, conversion does not seem to depend on temperature, and appears to be limited by the amount of liquid medium available as physical solvent. At intermediate tetralin/coal ratios,conversion generally increases with both factors: temperature and amount of solvent. However, retrogressive reactions are observed at 475°C which indicates that these reactions are produced at high temperatures when there is not enough hydrogen in the system As far as product distribution are concerned, it is observed that asphaltenes and preasphaltenes decrease, while oils + gases increase with temperature.