Negi Sanjay Singh, Kim Hak-Min, Cheon Beom-Su, Jeong Chang-Hoon, Roh Hyun-Seog, Jeong Dae-Woon
Industrial Technology Research Center, Changwon National University, 20 Changwondaehak-ro, Changwon, Gyeongnam 51140, Republic of Korea.
Department of Environmental Engineering, Changwon National University, 20 Changwondaehak-ro, Changwon, Gyeongnam 51140, Republic of Korea.
ACS Appl Mater Interfaces. 2023 Nov 8;15(44):51013-51024. doi: 10.1021/acsami.3c09312. Epub 2023 Oct 30.
H production via water-gas shift reaction (WGS) is an important process and applied widely. Cobalt-modified CeO are promising catalysts for WGS reaction. Herein, a series of Co/Nb-CeO catalysts were prepared by varying the rate of precipitant addition during the coprecipitation method and examined for hydrogen generation through WGS reaction. The rates of precipitant addition were 1, 5, 15, and 25 mL/min. We obtained ceria supported cobalt catalysts with different sizes and morphology such as 3, 8 nm nanoclusters, 30 nm cubic nanoparticles, and 50 nm hexagonal nanoparticles. The well dispersed small cobalt particles in Co/Nb-CeO that was prepared at 5 mL/min titration rate exhibit strong interaction between cobalt oxide and CeO that retards the reduction of CoO producing Co-CoO pairs. In contrast, 1-Co/Nb-CeO and 25-Co/Nb-CeO result in bigger and aggregated Co particles, resulting in fewer interfaces with CeO. The Co, Co, Ce, and O species are responsible for improved reducibility in Co/Nb-CeO catalysts and were quantitively measured using XPS, XAS, and Raman spectroscopy. The Co-CoO interface assists dissociation of the HO molecule; CO oxidation requires low activation energy and realizes a high turnover frequency of 9.8 s. The 5-Co/Nb-CeO catalyst achieved thermodynamic equilibrium equivalent CO conversion with efficient H production during WGS reaction at a gas hourly space velocity of 315,282 h. Successively, the 5-Co/Nb-CeO catalyst exhibited stable performance for straight 168 h attributed to stable CO-Co intermediate formation, achieving efficient inhibition of typical CO chemistry over the Co metal, suitable for hydrogen generation from waste derived synthesis gas.
通过水煤气变换反应（WGS）制氢是一个重要的过程且应用广泛。钴改性的CeO是有前景的WGS反应催化剂。在此，通过在共沉淀法中改变沉淀剂添加速率制备了一系列Co/Nb-CeO催化剂，并对其通过WGS反应制氢进行了研究。沉淀剂添加速率分别为1、5、15和25 mL/min。我们获得了具有不同尺寸和形态的二氧化铈负载钴催化剂，如3、8 nm纳米团簇、30 nm立方纳米颗粒和50 nm六方纳米颗粒。以5 mL/min滴定速率制备的Co/Nb-CeO中分散良好的小钴颗粒表现出氧化钴与CeO之间的强相互作用，这阻碍了CoO的还原，产生Co-CoO对。相比之下，1-Co/Nb-CeO和25-Co/Nb-CeO导致更大且聚集的Co颗粒，导致与CeO的界面更少。Co、Co、Ce和O物种负责提高Co/Nb-CeO催化剂的还原性，并使用XPS、XAS和拉曼光谱进行了定量测量。Co-CoO界面有助于H₂O分子的解离；CO氧化需要低活化能，并实现了9.8 s⁻¹的高周转频率。5-Co/Nb-CeO催化剂在315,282 h⁻¹的气时空速下进行WGS反应时，实现了与高效制氢相当的热力学平衡CO转化率。随后，5-Co/Nb-CeO催化剂由于稳定的CO-Co中间体形成而在168 h内表现出稳定的性能，实现了对Co金属上典型CO化学的有效抑制，适用于从废合成气中制氢。
