利用外源氢气纯化升级沼气的研究进展

摘要

沼气发酵过程存在产气速率低和甲烷浓度低两个普遍问题。从甲烷生成的反应机理来看，如果提供充足的氢气，能够把沼气中的CO2成分转化为CH4，既提高了甲烷的产量，又提高了甲烷的浓度。介绍了最近国内外在这个方向上的探索性研究成果。实验表明，利用外源氢气确实可以纯化升级沼气，在一定条件下还可以达到生物甲烷的品质（即CH4浓度高于95%）。分析了这项技术实用化需要解决的两个关键问题：强化H2气液传质及获取廉价氢源。最后，对这个方向进行了展望，并提出了一个光电催化产氢与厌氧发酵产甲烷耦合的设想方案。%Biogas fermentation has two general problems, low production rate and low methane concentration. From the reaction mechanism for methane formation, if external H2 is supplied, CO2 in the biogas can be converted into CH4, leading to increased yield and concentration of methane. Recently published experimental studies reported that biogas could be purified and upgraded to a quality as biomethane with the addition of hydrogen gas. However, to make this technology practical, two key problems should be resolved. One is to intensify H2 transfer from gas phase to aqueous phase at low mixing speeds. The other is to obtain hydrogen gas with economical methods. A scheme is suggested for biogas upgrading through the integration of H2 generation by photoelectrocatalysis and CH4 production by anaerobic fermentation.