甘油水蒸气重整制氢热力学分析

THERMODYNAMIC ANALYSIS OF HYDROGEN GENERATION VIA STEAM REFORMING OF GLYCEROL

采用吉布斯自由能最小化原理计算甘油水蒸气重整制氢过程的平衡组成,该模型经实验结果验证,吻合良好。考察温度、压力、水/甘油物质的量之比对H2、CO、CO2、CH4组成及选择性,积碳,原料平衡转化率及系统耗能的影响。计算结果表明:在高温低压及高水/甘油物质的量之比条件下有利于提高H2产率,水/甘油物质的量之比大于4时可有效避免积碳,在873 K下,水/甘油物质的量之比大于20时即可完全消除CH4;结合各反应条件对上述关键反应过程参数的影响,推荐反应温度为823~1023 K,反应压力为常压,水/甘油物质的量之比6∶1~46∶1。甘油水蒸气重整反应过程在反应温度1023 K及水/甘油物质的量之比为9的典型工况下系统耗能占系统产生总能量的30%以上。

Thermodynamic equilibrium for glycerol steam reforming to hydrogen was investigated using Gibbs free energy minimization method.The model matches the experimental results very well.The effects of the temperature,pressure and the ratio of steam-to-glycerol(S/G)on the reaction were investigated,such as compositions and selectivities of the products,the equilibrium yield,as well as system energy consumption.It is shown that higher temperature and lower pressure favor the production of hydrogen from glycerol;besides,to avoid carbon formation,S/G should be higher than 4;CH4 can be eliminate completely under the condition of 873 K and S/G of higher than 20.So the optimal conditions are reaction temperature of 823-1023 K,ambient pressure,S/G of 6∶1-46∶1.As a highly endothermic reaction,the system energy consumption of glycerol steam reforming occupied more than 30%of the total energy generated from the system in the typical condition of H2O/C3H8O3(mole/mole)=9,T=1023 K.