Canales Rafael, Barrio Victoria Laura
School of Engineering of Bilbao, University of the Basque Country (UPV/EHU), 48013 Bilbao, Spain.
Materials (Basel). 2023 Aug 29;16(17):5907. doi: 10.3390/ma16175907.
Catalysts derived from Ni/Al/Mg/Ce hydrotalcite were prepared via a co-precipitation method, varying the Ce/Al atomic ratio. All of the catalytic systems thus prepared were tested for CO methanation under dark and photocatalytic conditions (visible and ultraviolet) under continuous flow with the light intensity set to 2.4 W cm. The substitution of Al by Ce formed a solid solution, generating oxygen vacancies and Ce/Ce ions that helped shift the dissociation of CO towards the production of CH, thus enhancing the activity of methanation, especially at lower temperatures (<523 K) and with visible light at temperatures where other catalysts were inactive. Additionally, for comparison purposes, Ni/AlO-based catalysts prepared via wetness impregnation were synthesized with different Ni loadings. Analytical techniques were used for the characterization of the systems. The best results in terms of activity were as follows: Hydrotalcite with Ce promoter > Hydrotalcite without Ce promoter > 25Ni/AlO > 13Ni/AlO. Hydrotalcite, with a Ce/Al atomic ratio of 0.22 and a Ni content of 23 wt%, produced 7.74 mmol CH min·g at 473 K under visible light. Moreover, this catalyst exhibited stable photocatalytic activity during a 24 h reaction time with a CO conversion rate of 65% and CH selectivity of >98% at 523 K. This photocatalytic Sabatier enhancement achieved activity at lower temperatures than those reported in previous publications.
通过共沉淀法制备了不同Ce/Al原子比的Ni/Al/Mg/Ce水滑石衍生催化剂。对所有这些制备的催化体系在黑暗以及光催化条件下（可见光和紫外光）进行连续流动测试，以评估其CO甲烷化性能，光强度设定为2.4 W/cm²。用Ce取代Al形成了固溶体，产生了氧空位和Ce³⁺/Ce⁴⁺离子，有助于将CO的解离向CH₄的生成方向转移，从而提高甲烷化活性，特别是在较低温度（<523 K）下以及在其他催化剂无活性的温度下使用可见光时。此外，为了进行比较，通过湿浸渍法制备了不同Ni负载量的Ni/Al₂O₃基催化剂。采用分析技术对这些体系进行表征。在活性方面，最佳结果如下：含Ce促进剂的水滑石>不含Ce促进剂的水滑石>25Ni/Al₂O₃>13Ni/Al₂O₃。Ce/Al原子比为0.22且Ni含量为23 wt%的水滑石在473 K可见光下产生7.74 mmol CH₄ min⁻¹·g⁻¹。此外，该催化剂在24小时反应时间内表现出稳定的光催化活性，在523 K时CO转化率为65%，CH₄选择性>98%。这种光催化萨巴蒂尔增强效应在比以前出版物报道的更低温度下实现了活性。
