Olukayode Niyi, Yang Weijing, Xiang Kang, Ye Shenrong, Sun Zhigang, Han Zhenfei, Sui Sheng
Institute of Fuel Cell, Shanghai Jiao Tong University, Shanghai 200240, China.
State Key Laboratory of Space Power-Sources Technology, Shanghai Institute of Space Power-Sources, Shanghai 200245, China.
ACS Omega. 2022 Feb 23;7(9):7865-7873. doi: 10.1021/acsomega.1c06759. eCollection 2022 Mar 8.
Hydrogen production from the electrolysis of coal slurry is a promising approach under the condition of low voltage (0.8-1.2 V) and medium temperature. However, the rate of hydrogen production is slugged by poor anode kinetics, under an electrochemical condition that results from the collision of the coal particles with the anode surface. This paper reports a novel process that consists of two steps: the oxidation of the coal slurry by ferric ions(III) in a hydrothermal reactor at a temperature of 120-160 °C and the electro-oxidation of ferric ions(II) in the electrochemical cell to produce hydrogen. This technique circumvents the technical issues experienced in the conventional coal slurry electrolysis process by adopting a two-step process consisting of solid-liquid reactions instead of solid-solid reactions. This indirect oxidation process produced a current density of 120 mA/cm at room temperature and a voltage of 1 V, which is higher than the values reported in the conventional processes. An investigation of the oxidation mechanism was carried out via scanning electron microscopy, Fourier-transform infrared spectroscopy and elemental analysis. The results obtained showed that the oxidation of coal by ferric ions occurs from the surface to the inner parts of the coal particles in a stepwise manner. It was also revealed that the ferric ions in the media increased the active interfaces both of the coal particles and of the anode electrode. This explains the high hydrogen production rate obtained from this process. This novel discovery can pave the way for the commercialization of coal slurry electrolysis.
在低电压（0.8 - 1.2V）和中温条件下，通过煤浆电解制氢是一种很有前景的方法。然而，在煤颗粒与阳极表面碰撞产生的电化学条件下，由于阳极动力学较差，制氢速率受到阻碍。本文报道了一种由两步组成的新工艺：在120 - 160°C的水热反应器中用三价铁离子氧化煤浆，以及在电化学电池中将二价铁离子进行电氧化以产生氢气。该技术通过采用由固液反应而非固固反应组成的两步法，规避了传统煤浆电解过程中遇到的技术问题。这种间接氧化过程在室温下产生了120 mA/cm²的电流密度和1V的电压，高于传统工艺报道的值。通过扫描电子显微镜、傅里叶变换红外光谱和元素分析对氧化机理进行了研究。所得结果表明，三价铁离子对煤的氧化是从煤颗粒表面逐步向内部进行的。还发现介质中的三价铁离子增加了煤颗粒和阳极电极的活性界面。这解释了该过程获得的高制氢速率。这一新颖的发现可为煤浆电解的商业化铺平道路。
