Improving the Yield and Quality of Tar during Co-pyrolysis of Coal and Cotton Stalk

Co-pyrolysis of Shenmu coal (SM) and cotton stalk (CS) at different blend ratios were carried out in a tubular furnace. The pyrolysis temperature was up to 600 °C at 5 °C/min and kept for 15 min. The results indicated that there was an interactive effect between SM and CS, which increased the tar yield. Moreover, the content of light components in co-pyrolysis tar from all CS/SM blend ratios was higher than that in the tar derived from SM pyrolysis. This interaction not only increased tar yields but also upgraded the quality of tar in the co-pyrolysis process. Compared with the copyrolysis of de-ashed CS and SM, the inherent minerals of CS had great effects on the co-pyrolysis tar yield. The analysis results of n-hexane soluble extracted from co-pyrolysis tar by gas chromatography/mass spectrometry indicated that the organic matters of CS had a significant effect on the alkene formation of tar during co-pyrolysis. The maximal tar yield was 13.73 wt% (daf) and the yield of n-hexane soluble reached 11.13 wt% (daf) under optimum conditions.