氢气在无催化煤液化中的反应机理

REACTION MECHANISM OF HYDROGEN FOR DIRECT COAL LIQUEFACTION WITHOUT CATALYSTS

采用平衡液相取样法气体溶解度测定装置测定了氢气在萘中的溶解规律,并采用间歇式微型反应釜研究了氢气在无催化煤液化中的反应机理.结果表明:1)氢气在萘中的溶解随着温度和压力的升高而增加,溶解速率先快后慢,在5min时达到最大溶解量的76.21%左右,直到30min达到平衡;2)在萘溶剂的无催化煤液化反应中,氢气的溶解不是控制步骤,溶解氢参与液化反应的速度才是控制步骤;3)在较短时间的萘溶剂无催化煤液化时,氢气在萘溶剂中的预溶解提高了无催化煤液化的总转化率,其主要原因是部分预溶氢提前活化,使得煤液化反应初期活性氢增加;4)在较长时间的萘溶剂无催化煤液化时,预溶氢对总转化率的提高很小,但促进了液化产物的进一步裂解加氢轻质化.

In this paper,the solubility of hydrogen in naphthalene was measured by using vapor-liquid phase equilibrium sampling method.The reaction mechanism of hydrogen for direct coal liquefaction was investigated by liquefaction of Yanzhou coal using a 17 mL tubular resonance agitation microautoclave reactor.The results show：1） that hydrogen solubility in naphthalene increases with the increase of temperature and hydrogen partial pressure,and the solution rate overall appears first quick back slow trend.Hydrogen solubility within 5 min has reached 76.21% of the maximum under certain temperature and hydrogen partial pressure,then it continues to increase slowly and achieves the maximum for 30 min;2） that the control step of coal liquefaction without catalyst in naphthalene is not the solution rate of hydrogen but the reaction rate of dissolved hydrogen participating in liquefaction;3） that hydrogen pre-solution in naphthalene increases the total conversion of shorter coal liquefaction without catalyst,which is because partial dissolved hydrogen was activated in pre-solution process,resulting in the increase of active hydrogen in the initial stage of liquefaction reaction;4） that hydrogen pre-solution in naphthalene has a little contribution for the total conversion of longer coal liquefaction without catalyst,but it promotes the further hydrocracking and upgrading of liquefaction products.