La掺杂Ru/CeO2催化剂的制备及水相催化异辛醇氧化

Preparation of La-doped Ru/CeO2 Catalyst and Catalytic OxidationSofSIsooctanol in Aqueous Phase

摘要:

采用沉积-沉淀技术成功合成了Ru/La-CeO₂催化剂,并利用氧气作为绿色氧化剂,在水这一环境友好型溶剂中催化氧化异辛醇制备异辛酸。本研究系统地探索了压力、温度以及La掺杂比例等关键参数对催化剂效能及反应进程的影响,并通过一系列先进的表征技术,包括X射线衍射(XRD)、扫描电子显微镜(SEM)、氢气程序升温还原(H₂-TPR)、X射线光电子能谱(XPS)以及氧气程序升温脱附(O₂-TPD),全面评估了Ru/La-CeO₂催化剂的性能。研究结果显示,通过La元素的掺杂,Ru/CeO₂催化剂的性能实现了显著提升。在优化的反应条件下(温度为120℃,氧气压力为2 MPa,反应时间6 h,催化剂用量为异辛醇质量的5%)异辛醇的转化率高达95.9%,异辛酸的选择性也达到了98.2%。进一步分析发现,La掺杂进入CeO₂晶格后,La₃₊^{离子部分取代了原有的}Ce₄₊^离子,这一结构变化有效地促进了催化剂表面氧空位的增多。氧空位作为活性位点,在异辛醇水相氧化制备异辛酸的反应中扮演了至关重要的角色,其数量的增加使反应效率和选择性的显著提升。

Abstract:

The Ru/La-CeO2 catalyst was successfully synthesized using the deposition-precipitation technique and employed to catalyze the oxidation of isooctanol to isooctanoic acid in an environmentally friendly aqueous solvent, with oxygen serving as the green oxidant. This study systematically explored the influence of key parameters such as pressure, temperature, and La doping ratio on the catalyst"s efficiency and reaction progress. The performance of the Ru/La-CeO₂ catalyst was comprehensively evaluated through a series of advanced characterization techniques, including X-ray diffraction (XRD), scanning electron microscopy (SEM), hydrogen temperature-programmed reduction (H₂-TPR), X-ray photoelectron spectroscopy (XPS), and oxygen temperature-programmed desorption (O₂-TPD). The results revealed that the performance of the Ru/CeO₂ catalyst was significantly enhanced by La doping. Under optimized reaction conditions (a temperature of 120°C, an oxygen pressure of 2 MPa, a reaction time of 6 h, and a catalyst dosage of 5% by mass of isooctanol), the conversion rate of isooctanol reached 95.9%, with a selectivity for isooctanoic acid of 98.2%. Further analysis indicated that the incorporation of La into the CeO₂ lattice led to the partial substitution of Ce₄₊ ^{ions by La₃₊} ions. This structural change effectively promoted an increase in the number of oxygen vacancies on the catalyst"s surface. As active sites, these oxygen vacancies played a crucial role in the aqueous-phase oxidation of isooctanol to isooctanoic acid, and their increased number significantly improved the reaction efficiency and selectivity.