Co/ZrO_2/SiO_2催化剂F-T合成反应研究

采用等温积分固定床反应器,在小粒径催化剂、高空速、消除传质作用影响的条件下,对Co/ZrO2/SiO2催化剂上的F-T合成本征反应性能进行了详细考察,结果表明CH4和C2烃的生成活化能较高,导致其偏离Anderson-Schulz-Flory分布规律;在转化率不高的情况下,F-T合成中的CO消耗速率表现出对H2分压的线性依赖关系,而反应总压对CO转化率和产物分布的影响不明显。较高的反应温度和H2分压会促进烯烃的二次加氢反应,从而降低烃生成的链增长因子。H2O的分压过高会造成活性相Co0的氧化,同时抑制F-T反应活性且不利于二次反应的进行。对于以重质烃为目标产物的Co/ZrO2/SiO2催化剂而言,适宜的操作条件为:反应温度483K、V(H2)/V(CO)=2.0和反应压力2.0~3.0MPa。

Studies of the Fischer-Tropsch Synthesis over Co/ZrO2/SiO2 Catalyst

The intrinsic performance of the Fischer-Tropsch synthesis over Co/ZrO2/SiO2 catalyst is investigated. Using fine catalyst particles and high space velocity, the effects of external and internal mass transform limitation can-be neglected. The experimental results show that the apparent activation energies of CH4 and C2 hydrocarbons are higher than which of C3 and C4 hydrocarbons, which is responsible for their deviation from Anderson-Schulz-Flory distribution. When the CO conversion is not high, the rate of CO consumption exhibited a first-order dependency on hydrogen partial pressure. The influence of total reaction pressure is not marked for the CO conversion and product distribution. The secondary reaction of olefins can improve the formation of higher carbon-number hydrocarbons. The high temperature and H2/CO ratio in feed gas are favored to the secondary hydrogenation reaction, which will restrain the carbon chain growth. The byproduct, H2O, will oxidize the Co metal. High H2O partial pressure will restrain the CO consumption and secondary reactions of primary olefins. The appropriate reaction conditions are the temperature of 483 K, the pressure of 2.0-3.0 MPa and the H2/CO feed volume ratio of 2.0.