Coprocessing of a Turkish lignite with a cellulosic waste material: 3. A statistical study on product yields and total conversion

The objectives of this study were to evaluate statistically the effects of coprocessing parameters on liquefaction yields, to determine the key process variables affecting the oil+gas, oil and asphaltene yields and total conversion. A statistical experimental design based on Second Order Central Composite Desing was planned fixing the liquefaction period at 1 h. Parameters such as temperature, initial cold pressure, tetralin/(lignite+sawdust) and sawdust/lignite ratios coded as x1, x2, x3 and x4, respectively, were used. The parameters were investigated at five levels (−2, −1, 0, 1 and 2). The effects of these factors on dependent variables, namely, oil+gas, oil and asphaltene yields and total conversion were investigated. To determine the significance of effects, the analysis of variance with 99.9% confidence limits was used. It was shown that within the experimental ranges examined, temperature and sawdust/lignite ratio were the variables of highest significance for oil+gas yields, oil yields and total conversion.