固定床反应器中添加CO_2对费托合成反应的影响

Influence of CO_2 Addition on Catalytic Performance of Fe-Mn Catalyst for Fischer-Tropsch Synthesis

用固定床反应器研究了Fe-Mn催化剂上原料气中添加CO2对费托合成反应的影响.结果表明,在533K与反应总压为1.50MPa时,大量CO2的添加使得生成CO2的选择性迅速降低,烃的生成速率降低,烃的收率也有所降低,产物向轻组分方向偏移,有机含氧化合物的生成速率降低;在593K与合成气(H2+CO)分压为1.50MPa时,随着CO2分压的增加,CO消耗速率变化不大,而烃的生成速率缓慢升高,烃的收率有所升高,CO2的生成速率缓慢降低,H2O的生成速率明显加快.由于CO2的添加,促使水煤气变换反应向逆反应方向进行,降低了催化剂表面氢物种浓度,抑制了加氢反应,低碳烃的烯/烷比有所增大,同时提高了重质烃的选择性,且随着CO2分压的增加,有机含氧化合物的生成速率呈上升的趋势.

The effect of CO2 addition during Fischer-Tropsch synthesis was investigated over the Fe-Mn catalyst in a fixed-bed reactor. The CO2 addition enhanced the reverse reaction rate of the water-gas shift and inhibited the CO2 formation rate. The CO2 selectivity decreased rapidly when a large amount of CO2 was added into the feed gas （ n （H2）/n （CO） = 2.03, GHSV （Hi ＋ CO） = 4 010 h^-1 , p （total） = 1.50 MPa, T = 533 K）, while the hydrocarbon formation rate decreased slightly and the overall oxygenate formation rate decreased. Under the reaction conditions of n（H2）/n（CO） = 1.00, GHSV （H2 ＋ CO） = 8 000 h^-1, p（H2 ＋ CO） = 1.50 MPa, and T- 593 K, the CO2 addition decreased the surface hydrogen concentration, leading to an increase in olefin/ paraffin ratio and higher C5＋ selectivity in reaction products. The hydrocarbon formation rate appreciably increased with increasing CO2 partial pressure, and the hydrocarbon yield also gradually increased. In addition, the oxygenate formation rate also increased with CO2 partial pressure.