Department of Chemical and Environmental Technology, Universidad Rey Juan Carlos, C/Tulipán s/n, 28933 Móstoles, Madrid, Spain.
Materials and Sustainability Group, Department of Engineering, Universidad Loyola Andalucía, Avda. De las Universidades s/n, 41704 Dos Hermanas, Seville, Spain.
Molecules. 2021 Jan 22;26(3):583. doi: 10.3390/molecules26030583.
To improve the thermochemical energy storage (TCS) behavior of MnO, several Mn-Mo oxides with varying amounts of MoO (0-30 wt%) were prepared by a precipitation method. The physico-chemical properties of the solids were studied by N adsorption-desorption, X-ray diffraction (XRD), scanning electron microscopy (SEM), and H-temperature-programmed reduction (TPR), while their TCS behavior was determined by thermogravimetric analysis coupled with differential scanning calorimetry (TGA-DSC). Apart from MnO and MoO phases, XRD revealed a mixed MnMoO phase for MoO loadings equal or higher than 1.5 wt%. All samples showed a well-formed coral-like surface morphology, particularly those solids with low MoO contents. This coral morphology was progressively decorated with compact and Mo-enriched MnMoO particles as the MoO content increased. TPR revealed that the redox behavior of MnO was significantly altered upon addition of Mo. The TCS behavior of MnO (mostly oxidation kinetics and redox cyclability) was enhanced by addition of low amounts of Mo (0.6 and 1.5% MoO) without significantly increasing the reduction temperature of the solids. The coral morphology (which facilitated oxygen diffusion) and a smoother transition from the reduced to oxidized phase were suggested to be responsible for this improved TCS behavior. The samples containing 0.6 and 1.5 wt% of MoO showed outstanding cyclability after 45 consecutive reduction-oxidation cycles at high temperatures (600-1000 °C). These materials could potentially reach absorption efficiencies higher than 90% at concentration capacity values typical of concentrated solar power plants.
为了改善 MnO 的热化学储能 (TCS) 性能，通过沉淀法制备了几种具有不同 MoO 含量（0-30wt%）的 Mn-Mo 氧化物。通过 N 吸附-解吸、X 射线衍射 (XRD)、扫描电子显微镜 (SEM) 和 H-程序升温还原 (TPR) 研究了固体的物理化学性质，而其 TCS 行为则通过热重分析与差示扫描量热法 (TGA-DSC) 来确定。除了 MnO 和 MoO 相之外，XRD 还表明对于 MoO 负载量等于或高于 1.5wt%的样品，存在混合的 MnMoO 相。所有样品都表现出形成良好的珊瑚状表面形貌，特别是那些 MoO 含量较低的固体。随着 MoO 含量的增加，这种珊瑚形貌逐渐被致密且富含 Mo 的 MnMoO 颗粒所装饰。TPR 表明，MnO 的氧化还原行为在添加 Mo 后发生了显著改变。MnO 的 TCS 行为（主要是氧化动力学和氧化还原循环能力）通过添加少量 Mo（0.6 和 1.5%MoO）得到了增强，而固体的还原温度没有显著增加。这种改进的 TCS 行为归因于珊瑚形态（有利于氧气扩散）和从还原相到氧化相的更平滑转变。在高温（600-1000°C）下进行 45 次连续还原-氧化循环后，含有 0.6 和 1.5wt%MoO 的样品表现出出色的循环稳定性。这些材料在浓度能力值典型的集中太阳能发电厂中，有可能达到吸收率高于 90%的水平。
