Fe-Mn工业催化剂F-T合成详细机理动力学研究 I.反应性能及初步反应机理

STUDY OF F-T SYNTHESIS DETAILED MECHANISM KINETICS OVER Fe-Mn INDUSTRIAL CATALYST Ⅰ. Catalyst Performance and Preliminary Mechanism

为探讨Fe-Mn工业催化剂F-T合成反应初步机理最终获得详细机理动力学模型,在严格恒温的固定床反应器上考察反应性能并与铁基无锰催化剂比较。根据Fe-Mn催化剂的反应特性,提出与铁基无锰催化剂不同的初步反应机理及网络:(1)烯烷烃遵循不同的链增长方式,烯烃由烯基表面物种生成,烷烃由烷基表面物种生成;(2)烯烃遵循两种链终止方式。

To obtain F-T synthesis detailed mechanism kinetics over an Fe-Mn industrial catalyst, its F-T performance was investigated in a strictly thermostable fixed-bed reactor. The changes of CO conversion and CO 2 selectivity with temperature and pressure over an Fe-Mn catalyst are the same as that of maganese-free iron catalysts. A large of space velocity, from 2000h -1 to 6000h -1 , was used. And a different CO 2 selectivity occurred at higher space velocity compared with lower space velocity. The phenomenon is elucidated with C + 1 STY and CO 2 STY. The formed methane is inhibited and there exists no 'C 2-trap' phenomenon over an Fe-Mn catalyst. Ethane linearly changes with temperature and pressure. C 3 and C 4 gas phase hydrocarbons have a jump at 573K. And then they are basically unchanged. It is noted that the space velocity has no apparent influence on the product distribution. It is found that alkene has a different chain growth trend from alkane. Combined with the result of literatures, a preliminary reaction mechanism is supposed, in which alkene is produced from the unsaturated chain while alkane from saturated one.