The effects of cornstalk addition on the product distribution and yields and reaction kinetics of lignite liquefaction

The cornstalk-assisted direct lignite liquefaction was conducted by using a resonance agitation micro-autoclave heated by a salt bath. The effects of reaction temperature (360 °C, 390 °C, and 420 °C) and time (5 min, 15 min, 30 min, and 60 min) on the distribution and yields of liquefaction products (asphaltene, preasphaltene, oil, and gas) were investigated. The results show that the reaction temperature has significant effect on the distribution and yields of products in the cornstalk-assisted direct coal liquefaction. At 360 °C, the reaction from preasphaltene to asphaltene is the rate-limiting step of the overall co-liquefaction process, while at 420 °C the reaction from asphaltene to oil becomes the rate-limiting step. A kinetic model is proposed and the kinetics analysis shows that the activation energy for the reaction from raw material to preasphaltene and asphaltene is 41.9 kJ/mol, while that for the reaction from preasphaltene and asphaltene to oil and gas is 61.4 kJ/mol. The addition of cornstalk can considerably improve the reaction kinetics of the co-liquefaction of Shengli coal and cornstalk.