神府煤热解-活化耦合反应产物特性及机制研究

利用两段式固定床反应装置,研究了神府煤热解-活化耦合产物的特性,探讨了热解温度及活化剂(H_2O(g)、CO_2和H_2O(g)/CO_2)对产物性能的影响,揭示了热解-活化耦合反应机制。结果表明,热解温度对半焦的CO_2化学反应性影响较小;采用热解-活化两段耦合工艺,可使神府煤热解的焦油产率明显提高,产率最高为17.8%;不同活化剂对两段耦合过程产生的混合煤气(mixture coal gases,MCG)和焦油产率影响为H_2O(g)H_2O(g)/CO_2CO_2,其焦油组分均以饱和分和芳香分为主;采用H_2O(g)/CO_2(1∶1)活化剂,可有效提高活性炭的比表面积,其BET比表面积为845.37 m~2/g。热解-活化耦合机制主要为活化段产生的合成气(synthesis gases,SG)为热解段煤的加氢热解提供了氢源,丰富的氢自由基促进了煤的加氢热解反应,改变了耦合过程的产物分布和特性。

Mechanism and product characteristics of pyrolysis-activation coupling reaction of Shenfu coal

The characteristics of products from Shenfu coal pyrolysis-activation coupling reaction were investigated in a two-stage fixed bed reactor.The effect of pyrolysis temperature and activating agents(H₂O(g),CO₂ and H₂O(g)/CO₂) on the characteristics of products was analyzed.The mechanism of pyrolysis-activation coupling reaction was revealed.The results show that the pyrolysis temperature has little effect on the CO₂ chemical reactivity of the chars.The tar yield of Shenfu coal pyrolysis is significantly increased by using pyrolysis-activation coupling process,and the tar yield is up to 17.8%.The effect of different activating agents on the yield of mixed coal gases(MCG)and tar is in the order of H₂O(g)>H₂O(g)/CO₂>CO₂ and the main components of tar are saturates and aromatics.The specific surface area of activated carbon can be effectively improved by using H₂O(g)/CO₂ as the activating agents,and the BET specific surface area reaches to 845.37 m²/g.The mechanism of pyrolysis-activation coupling process is that the synthesis gases(SG) from the activation section can provide hydrogen source for coal hydropyrolysis in pyrolysis section,and the rich hydrogen radicals can promote the reaction and change the product distribution and properties.