流化床内生物质合成气制取甲烷的实验与宏观动力学

Experiment and Macro-Kinetics on Biomass Syngas Methanation in a Fluidized Bed Reactor

为了研究低温低压下流化床反应器中生物合成气催化制取甲烷过程,制备了Ni基甲烷化催化剂,对其进行表面形态分析,并考察了该催化剂催化合成气制备甲烷反应中操作条件对甲烷化过程的影响。实验结果表明,在低温低压的条件下,合成气甲烷化过程受到操作参数(反应温度、压力、空速和氢碳比等)的影响较大。较高的反应压力和氢碳比有利于甲烷的生成,反应温度存在最佳值,空速则有一折中值。根据实验结果,考虑到温度对甲烷生成的影响,引入了基于甲烷化反应温度的修正系数,建立了低温低压下合成气制备甲烷的宏观动力学模型。实验数据与模拟数据比较符合,验证了所建宏观动力学模型的正确性,从而为准确描述低温低压下合成气催化制取甲烷的过程奠定基础。

To study about methane synthesis process from biomass syngas at low temperature and pressure over nickel-based catalysts in a fluidized bed reactor, the nickel-based methanation catalysts were prepared with impregnation method and characterized. The effect of operating conditions on methanation process over the synthesized nickel-based catalyst was also investigated. The performance evaluation of methanation catalyst was conducted in a fluidized bed reactor by two performance indexes-CH4 selectivity and CO conversion. The experimental results showed that the catalyst performance was greatly influenced by the methanation temperature, pressure, space velocity and volume ratio of H2 to CO (H2/CO). Higher reaction pressure and H2/CO were in favor of the methanation, while there exists an optimal methanation temperature and a compromising space velocity corresponding to the highest CH4 selectivity and CO conversion. According to the experimental results, a macro-kinetic model of syngas methanation at low temperature and pressure over the nickel-based catalysts was built up after introducing a corrected parameter based on the reaction temperature. The experimental data are in good agreement with the simulation data, which verifies the correctness of the established macro-dynamics.