CO2气氛对胜利褐煤热解过程的影响

以5-8 mm胜利褐煤为研究对象，利用固定床反应器，在400-700℃、CO₂气氛下进行热解实验，研究了CO₂气氛对煤热解气、液、固三相产物分布的影响，探讨了CO₂对煤焦结构作用的机理。研究表明，与N₂气氛相比，CO₂气氛热解提高焦油和热解水产率，降低热解气和半焦产率；400和500℃时，CO₂气氛下形成的半焦孔隙结构和总孔体积没有明显的变化，600和700℃时，CO₂气氛下所得半焦的比表面积及孔容较N₂气氛下的大，是与煤焦内部挥发分大量释放以及CO₂进入孔道与活性位反应有关；煤热解过程中CO₂的引入能促进煤焦中3-5环芳香结构的消耗，导致煤焦结构芳香度的提高；600和700℃时，CO₂气氛下热解气中H₂和CH₄产率低，同时CO₂能与煤焦发生气化反应显著提高CO含量。

Effect of CO2 on pyrolysis behavior of Shengli lignite

The pyrolysis of Shengli lignite (5-8 mm) under CO₂ atmosphere was investigated at the temperature from 400 to 700℃ in a fixed bed reactor, the effect of CO₂ on the distribution of gas, solid and liquid phase in the product was analyzed, and the influence mechanism on the char structure under CO₂ atmosphere was explored. The results indicate that the yields of tar and water from pyrolysis under CO₂ atmosphere are higher than that under N₂ atmosphere, with a decrease in char and gas yield. At 400℃ and 500℃, the surface area and pore volume of the char prepared under CO₂ atmosphere are nearly the same as that under N₂ atmosphere, while at 600 and 700℃, the surface area and pore volume of the char prepared under CO₂ atmosphere are higher than that under N₂ atmosphere. It maybe attributes to that CO₂ can not only promote the release of volatile, but can also react with the active sites in the channels of char. The introduction of CO₂ into pyrolysis can increase the aromaticity of char due to the consumption of 3-5 rings aromatic structures. The yields of H₂ and CH₄ obtained from pyrolysis under CO₂ atmosphere are lower than that obtained under N₂ atmosphere at 600 and 700℃, and the yield of CO is much higher because of the occurrence of the char-CO₂ reaction.