Effect of solvent characteristics on reaction behavior of hydroliquefaction intermediate products from Naomaohu coal

To explore effect of solvent characteristics on reaction behavior of coal hydroliquefaction intermediate products, coal from Naomaohu in Xinjiang as raw material, tetralin, recycle solvent and decalin as hydrogen-donor solvents, hydroliquefaction experiments were performed in a high-pressure stirred reactor, and change of free radical concentration of asphaltene was analyzed by EPR. The results indicate that asphaltene in tetralin is formed in large quantities and transformed at the same time with increasing reaction temperature, the yield is from 12.92% at 290 ℃ to a maximum of 34.13% at 350 ℃ and then to 15.98% at 430 ℃. The asphaltene yield in recycle solvent continues to rise first, with 31.89% at 290 ℃ and a maximum of 47.96% at 400 ℃, and then decreases to 33.90% due to coking reaction. The change of asphaltene yield in decalin is consistent with that in tetralin. The change of free radical concentration of asphaltene is the same in three solvents, reaching the maximum at 350 ℃, which is 1.778×10¹⁸, 2.323×10¹⁸ and 1.930×10¹⁸/g respectively. On the whole, the values of free radical concentration of asphaltene in recycle solvent are higher than those in tetralin, and that in decalin is between the two solvents. But the g value in tetralin and recycle solvent is between 2.00323 and 2.00403, and the change is consistent with that of CO_x content in gas products.