Fe~(3+)辅助煤浆氧化制氢研究

利用Fe~(3+)/Fe~(2+)电对的相互转化原理,在水热反应釜中用Fe~(3+)氧化煤浆得到Fe~(2+),将Fe~(2+)在电解槽中电解氧化,在阴极产生氢气,从而通过两步反应形成一个新的煤浆电氧化制氢工艺。进行了九次水热-电解循环实验,在恒电压(1V)条件下,测试了电解反应的电流密度和累积电量的数据,并对循环实验前期、中期、后期的三个阶段煤样品进行了扫描电镜(SEM)、比表面积(BET)、热重(TG)、红外光谱(FT-IR)等表征分析。研究表明,相对于通常煤浆电氧化制氢工艺,这种"两步法"煤浆制氢新工艺具有更高的反应速率,初始电流密度约为60 m A/cm2,而传统的"一步法"煤浆制氢工艺初始电流密度均不超过10 m A/cm~2。表征分析结果很好地反映了煤颗粒在这种制氢工艺过程中的形态、结构、成分的变化,从而解释了在新的煤浆氧化制氢工艺中的Fe~(3+)/Fe~(2+)转化的反应机理。

Hydrogen production from oxidation of coal slurries assisted by ferric ions

A novel method of hydrogen production from oxidation of coal slurries using the mutual transformation of Fe³⁺ and Fe²⁺ was studied. At the first step, in a boiling kettle coal slurries are oxidized by Fe³⁺ into Fe²⁺ . Then Fe²⁺ is oxidized in an anode chamber and hydrogen is produced in cathode chamber. The two steps are combined to form a cycle to produce hydrogen. Nine cycles were performed at constant voltage (1 V) and the current densities and accumulated electric quantities at each cycle were investigated. The coal samples before, during and after reaction were analyzed with scanning electron microscope (SEM), BET specific surface area, thermal gravity (TG) and Fourier transform infrared spectrum (FT-IR). The results show that hydrogen production of "two-step" cycle processes has a higher reaction rate. The initial current density is about 60 mA/cm², while that of traditional "one-step" process is usually less than 10 mA/cm². The characterizations give a clear understanding on the changes of coal particles in morphology, structure and composition during the cycles, and also reveal the reaction mechanism of mutual transformation between Fe³⁺ and Fe²⁺.