Abahussain Abdulaziz A M, Al-Fatesh Ahmed S, Rajput Yuvrajsinh B, Osman Ahmed I, Alreshaidan Salwa B, Ahmed Hamid, Fakeeha Anis H, Al-Awadi Abdulrhman S, El-Salamony Radwa A, Kumar Rawesh
Chemical Engineering Department, College of Engineering, King Saud University, P.O. Box 800, Riyadh 11421, Saudi Arabia.
Department of Chemistry, Indus University, Ahmedabad, Gujarat 382115, India.
ACS Omega. 2024 Feb 14;9(8):9309-9320. doi: 10.1021/acsomega.3c08536. eCollection 2024 Feb 27.
Zirconia-alumina-supported Ni (5Ni/10ZrO+AlO) and Sr-promoted 5Ni/10ZrO+AlO are prepared, tested for carbon dioxide (CO) methanation at 400 °C, and characterized by X-ray diffraction, X-ray photoelectron spectroscopy, surface area and porosity, infrared spectroscopy, and temperature-programmed reduction/desorption techniques. The CO methanation is found to depend on the dispersion of Nickel (Ni) sites as well as the extent of stabilization of CO-interacted species. The Ni active sites are mainly derived from the reduction of 'moderately interacted NiO species'. The dispersion of Ni over 1 wt % Sr-promoted 5Ni/10ZrO+AlO is 1.38 times that of the unpromoted catalyst, and it attains 72.5% CO conversion (against 65% over the unpromoted catalyst). However, increasing strontium (Sr) loading to 2 wt % does not affect the Ni dispersion much, but the concentration of strong basic sites is increased, which achieves 80.6% CO conversion. The 5Ni4Sr/10ZrO+AlO catalyst has the highest density of strong basic sites and the highest concentration of active sites with maximum Ni dispersion. This catalyst displays exceptional performance and achieves approximately 80% CO conversion and 70% methane (CH) yield for up to 25 h on steam. The unique acidic-basic profiles composed of strong basic and moderate acid sites facilitate the sequential hydrogenation of formate species in the CO-free CH route.
制备了氧化锆 - 氧化铝负载的镍（5Ni/10ZrO₂ + Al₂O₃）和锶促进的5Ni/10ZrO₂ + Al₂O₃，在400℃下对其进行二氧化碳（CO₂）甲烷化测试，并通过X射线衍射、X射线光电子能谱、表面积和孔隙率、红外光谱以及程序升温还原/脱附技术对其进行表征。发现CO₂甲烷化取决于镍（Ni）位点的分散度以及与CO相互作用物种的稳定程度。Ni活性位点主要来源于“适度相互作用的NiO物种”的还原。在1 wt% Sr促进的5Ni/10ZrO₂ + Al₂O₃上Ni的分散度是未促进催化剂的1.38倍，其CO₂转化率达到72.5%（未促进催化剂为65%）。然而，将锶（Sr）负载量增加到2 wt%对Ni分散度影响不大，但强碱位点浓度增加，CO₂转化率达到80.6%。5Ni4Sr/10ZrO₂ + Al₂O₃催化剂具有最高的强碱位点密度和最高的活性位点浓度以及最大的Ni分散度。该催化剂表现出卓越的性能，在蒸汽存在下长达25小时内实现了约80%的CO₂转化率和70%的甲烷（CH₄）产率。由强碱和中强酸位点组成的独特酸碱分布有利于在无CO的CH₄生成途径中甲酸物种的连续氢化。
