生物油模型化合物水相重整制氢热力学分析

Thermodynamic Analysis of Hydrogen Production by Aqueous Phase Reforming of Three Model Compounds in Bio-oils

利用Gibbs自由能最小化原理对生物油模型化合物水相重整制氢过程进行了热力学平衡计算,考察了反应温度为340-660 K、压力比psys/pH2O为0.1-2.0时两个变量对H2选择性、CH4选择性、积碳以及原料转化率的影响。计算结果表明,当体系存在甲烷化与积碳反应时,原料转化率大于99.99%且无固态碳生成,但甲烷化较制氢反应热力学更有利。限制甲烷化反应后可提高H2选择性,其产氢机理主要为原料的直接裂解反应,且1 mol甲醇、乙酸与乙二醇可分别生成约0.999、1.940、1.999 mol的固态碳。同时限制甲烷化反应和积碳反应,在反应温度500 K、压力比psys/pH2O为1.1时,水相重整甲醇、乙酸、乙二醇可得到H2选择性为74.98%、66.64%、71.38%,且3种原料转化率均大于99%。

Thermodynamic analysis employing Gibbs free energy minimization for aqueous phase reforming of three model compounds in bio-oils for hydrogen production was presented.Effect of temperature（340～660K） and pressure ratio psys/pH2O（0.1～2.0） on H2 and CH4 selectivity,carbon formation and conversion of model compounds were calculated.The results showed that when considering both methanation and carbon formation reactions,the conversion of the model compounds were over 99.99% and no carbon formation was found,but mathanation was far more thermodynamically favorable than hydrogen production reaction.H2 selectivity were greatly improved without mathanation.Further analysis showed that the H2 production mechanism was mainly related to directly cracking of model compounds other than to aqueous reforming reaction,however,it was found that about 0.999,1.940,1.999 mole solid carbon formed when feeding per mole of methanol,acetic acid and ethylene glycol in the inlet streams.After restricting both mathanation and carbon formation reaction in the system,aqueous phase reforming of methanol,acetic acid and ethylene glycol at temperature of 500K and psys/pH2O of 1.1 could achieve H2 selectivity of 74.98%,66.64%,71.38%,and the conversion of the feedstocks were over 99%.