González-Vargas P E, Salinas-Gutiérrez J M, Meléndez-Zaragoza M J, Pantoja-Espinoza J C, López-Ortiz A, Collins-Martínez V
Departamento de Ingeniería y Química de Materiales, Centro de Investigación en Materiales Avanzados, S.C. Miguel de Cervantes 120 Chihuahua Chih. 31109 México
RSC Adv. 2021 Sep 2;11(47):29453-29465. doi: 10.1039/d1ra05077j. eCollection 2021 Sep 1.
NiWO with a volumetric storage density (VSD) of 496 g L was studied to evaluate its H storage potential as an oxygen carrier under a chemical looping (CL) process scheme. The material was synthesized by precipitation and calcined at 950 °C for 5 hours in air. Characterization consisted in XRD, BET surface area, SEM and EDS analysis. NiWO hydrogen storage reduction-oxidation evaluation was performed by TGA using 5% v H/Ar and 2.2% v HO/Ar at 800 °C. Global kinetics for the reduction step was studied from 730 to 870 °C using 2 to 5% v of H/Ar. While oxidation kinetics was examined from 730 to 870 °C using 0.8 to 2.2% v HO/Ar. A hydrogen storage multicycle stability test was performed by exposing NiWO to 17 consecutive redox cycles. XRD results of the synthesized material indicate NiWO as the only crystalline phase. Fully reduced material found only W and Ni species, while reoxidation led back to NiWO. BET surface area of synthesized material was 4.25 m g. SEM results showed fresh NiWO composed of non-porous large particles (1-5 μm). After reduction, the material shown a porous coral-like morphology with particles between 50 to 100 nm. EDS analysis results confirmed the compositions of the reduced (Ni + W) and fully oxidized NiWO species, respectively. Oxygen carrier reaction conversions for both reduction and regeneration steps were 100%. Global kinetic studies indicate a first order reaction for the two reduction steps and during oxidation, with activation energies of 22.1, 48.4 and 53.4 kJ mol for the two reduction and oxidation steps, respectively. NiWO multicycle stability test shown no loss of VSD and fast reduction and oxidation kinetics under the studied conditions after seventeen consecutive redox cycles, which confirms the potential of this material with respect to current oxygen carriers reported in the literature for hydrogen storage applications.
研究了体积储存密度（VSD）为496 g/L的NiWO，以评估其在化学链（CL）工艺方案下作为氧载体的储氢潜力。该材料通过沉淀法合成，并在空气中950℃煅烧5小时。表征包括XRD、BET表面积、SEM和EDS分析。通过TGA在800℃下使用5% v H₂/Ar和2.2% v H₂O/Ar对NiWO储氢还原-氧化进行评估。在730至870℃下使用2%至5% v的H₂/Ar研究还原步骤的整体动力学。而在730至870℃下使用0.8%至2.2% v的H₂O/Ar检查氧化动力学。通过使NiWO经历17个连续的氧化还原循环进行储氢多循环稳定性测试。合成材料的XRD结果表明NiWO是唯一的晶相。完全还原的材料仅发现W和Ni物种，而再氧化则变回NiWO。合成材料的BET表面积为4.25 m²/g。SEM结果显示新鲜的NiWO由无孔大颗粒（1-5μm）组成。还原后，材料呈现出多孔珊瑚状形态，颗粒在50至100nm之间。EDS分析结果分别证实了还原态（Ni + W）和完全氧化态NiWO物种的组成。还原和再生步骤的氧载体反应转化率均为100%。整体动力学研究表明，两个还原步骤和氧化过程均为一级反应，两个还原和氧化步骤的活化能分别为22.1、48.4和53.4 kJ/mol。NiWO多循环稳定性测试表明，在连续17个氧化还原循环后的研究条件下，VSD没有损失，还原和氧化动力学较快，这证实了该材料相对于文献中报道的当前用于储氢应用的氧载体的潜力。
