Abstract:

Secondary catalytic reactions of primary volatiles from oil shale pyrolysis were characterized by using a two-stage reactor to study the effects of different catalytic materials,reaction atmospheres and residence time on oil/gas yield and quality.The results showed that comparison with FCC catalyst as bed materials in the 2nd stage,the shale ash possessed relatively moderate activity for adjusting the secondary reaction of pyrolysis volatiles in the applied range of residence time.Using steam as the reaction atmosphere could further enhance the liquid yield by 5% and suppress the C₂-C₃ hydrocarbons in the cracked gas.The heavy oil fractions,such as vacuum gas oil (VGO,>350℃),could be converted into light oil fractions by the catalytic effects of shale ash,and correspondingly the boiling range of pyrolysis oil tended to be lighter with higher residence time.Oil components analyzed with GC-MS demonstrated that steam could effectively inhibit the over-cracking of aliphatic hydrocarbons at shorter residence time (<3 s),and thus increase the gasoline and diesel fractions by over 20% compared with the N₂ atmosphere.However,at higher residence time (3-5 s) the VGO fractions were prone to be condensed as coke,and as a result profoundly decreased the pyrolysis oil yield.

Key words: oil shale, pyrolysis, catalytic effect, secondary conversion, residence time

摘要：

采用两段反应器对油页岩热解初级挥发分进行二次催化反应特性研究，考察了第2段反应器内不同的催化载体、反应气氛与停留时间对油气收率及品质的影响。结果表明，在考察的停留时间范围内页岩灰具有相对适中的催化活性来调控热解挥发分产物的二次反应，水蒸气气氛能够进一步提高热解油收率约5%，并能够在一定程度上抑制裂解气体中C₂~C₃组分的生成。页岩灰作为催化载体能够转化热解油中VGO（馏程>350℃）等重质组分，随停留时间增加油品馏程向轻组分转移。油品组分GC-MS结果表明，较短停留时间内（<3 s），水蒸气添加能够有效抑制热解油中脂肪烃类的过度裂解，与氮气相比提高汽柴油馏分含量20%以上。过长的停留时间（3~5 s）会造成VGO等馏分缩聚生成焦炭，从而大幅降低热解油收率。

关键词: 油页岩, 热解, 催化作用, 二次转化, 停留时间