镍基焦油裂解催化剂再生特性及粉尘作用机理研究

在常压固定床反应器中,考察1.0%NiO/0.1%MgO-Al2O3催化剂的稳定性和原位再生性能,并在进料中引入粉尘以模拟真实的煤与生物质热解气化的含尘环境。结果表明,随着反应温度的升高,催化剂的活性提高,寿命缩短。该催化剂在循环再生实验中表现出良好的耐久性,再生温度为800℃时水热失活现象显著,优选的再生温度为600~700℃,再生时间20 min。随着再生剂中水蒸气比例的增加,催化剂的比表面积和孔结构逐渐发生变化。EPMA和XRD表征结果表明,引入粉尘后并未改变催化剂的组成,引入MgO后会形成(Mg0.4Al0.6)Al1.8O4晶相。SiO2具有促进积炭产生的作用,MgO则对积炭的产生具有一定的阻滞作用。适当降低空速可减弱SiO2等惰性粉尘对催化剂活性的负面作用。

Study on regeneration characteristics and dust deposition mechanism of nickel based tar-cracking catalyst

The catalysis and in-situ regeneration of 1.0%NiO/0.1%MgO-Al₂O₃ catalyst were investigated in an atmospheric fixed bed reactor, in which the dust was also introduced in the feed to simulate the real dust environment of coal and biomass pyrolysis. The results show that the catalyst has a higher activity but a shorter life as the reaction temperature increases. Cycle regeneration of the catalyst exhibits a good durability, while a significant hydrothermal deactivation phenomenon happens at the regeneration temperature of 800 ℃. As a result, the preferable regeneration temperature range of 600~700 ℃ and regeneration time of 20 min are determined. The increased ratio of air/steam will gradually change the specific surface area and pore structure of the catalyst. EPMA and XRD results show that the introduction of dust does not change the composition of catalyst except the introduction of MgO that will be converted to a new phase of (Mg_0.4Al_0.6)Al_1.8O₄. MgO plays a positive anti-carbon deposition role, while SiO₂ is reverse. The negative effect of SiO₂ on the activity of catalyst can be reduced by a lower operating gas velocity.