Pt/CeL重整催化剂的制备及其石脑油芳构化性能

为克服常规氧化铝重整催化剂氯离子流失及其对设备的腐蚀等问题,通过离子交换法制备了Ce~(3+)改性的L分子筛,采用浸渍法制备了Pt/CeL重整催化剂;用XRD、N_2吸附-脱附、NH_3-TPD和Py-FTIR等手段对载体和催化剂进行了表征,并以硫含量为0.50μg/mL的工业精制石脑油为原料,在固定床微型反应装置上评价了Pt/CeL催化剂的重整芳构化性能。结果表明,Ce~(3+)离子交换可提高载体的酸量和酸强度,而不会破坏L分子筛的骨架结构;Ce~(3+)改性后的Pt/CeL催化剂其重整芳构化性能明显提高,活性与选择性达到氧化铝型商业重整催化剂的水平,说明适当的酸性对重整催化剂芳构化反应有显著的促进作用。     

稀土掺杂对氯化氢氧化制氯气CuO-CeO2-SiO2催化剂结构和性能的影响

CuO-CeO₂-SiO₂ and rare-earth-doped CuO-Ce_0.9M_0.1O₂-SiO₂ (M=La, Pr, Nd) catalysts for recycling Cl₂ from HCl oxidation were prepared by a template method, using activated carbon as a hard template. The catalyst structures were determined using X-ray diffraction (XRD), N₂ adsorption-desorption, transmission electron microscopy (TEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and H₂ temperatureprogrammed reduction (H₂-TPR). The catalytic performances were also investigated. The results showed that La, Pr, and Nd cations were incorporated into the CeO₂ lattice and formed nanosized solid solutions; this greatly reduced the catalyst grain sizes, leading to higher surface areas. In addition, the oxygen vacancy concentrations were significantly improved. The changes in the structures and surface properties of the solid solutions significantly affected the HCl catalytic oxidation performances. The order of the activities of various catalysts was CuO-Ce_0.9La_0.1O₂-SiO₂>CuO-Ce_0.9Nd_0.1O₂-SiO₂>CuO-Ce_0.9Pr_0.1O₂-SiO₂>CuO-CeO₂-SiO₂. The oxygen vacancy concentrations of the solid solutions were strongly related to their catalytic activities. However, the structures and performances of the Ce_0.9M_0.1O₂-SiO₂ catalysts showed that an increase in the number of oxygen vacancies resulted in decreased catalytic activities of the solid solutions. Kinetic studies showed that oxygen adsorption could be the rate-determining step for rare-earth-doped catalysts; a higher oxygen vacancy concentration in the solid solution led to a slower reaction rate when the volumetric flow ratio of O₂ to HCl was 1. For the CuOCe_0.9M_0.1O₂-SiO₂ catalysts, spillover of oxygen species in the solid solution into the highly dispersed CuO interfaces was enhanced, which increased the overall reaction rate and gave high activity.     

Pd/CZ三效催化剂中钯的团聚现象研究

通过浸渍法制备了一系列负载0.5%（重量百分比）Pd的氧化铈-氧化锆（NDK-84，由日本新日本电工株式会社提供）催化剂材料，并通过全面的表征手段，包括扫描电子显微镜（SEM）、透射电子显微镜（TEM）、高分辨透射电子显微镜（HR-TEM）、元素分布、X-射线衍射（XRD），氮气吸脱附测试与比表面积和孔径分布分析（BET）、X射线光电子能谱（XPS）等，研究了不同Pd前驱体和不同热老化处理条件、H₂还原条件对Pd在铈锆固溶体上的分散、生长与烧结行为的影响，并评估了它们的三效催化活性.结果表明，热老化处理过程与还原过程显著影响了Pd在氧化物载体表面上的分散，因此导致不同的催化活性.     

(Sm0.5Gd0.2Nd0.3)2(Hf0.3Ce0.7)2O7复合氧化物的热物理性能

为寻求新型热障涂层用陶瓷材料,本文采用高温固相烧结法制备了(Sm_0.5Gd_0.2Nd_0.3)₂(Hf_0.3Ce_0.7)₂O₇复合氧化物。利用XRD分析了其晶体结构,SEM分析其显微组织,膨胀仪测试其热膨胀性能,激光热导仪测试其热扩散系数。结果表明,成功制备了具有单一萤石晶体结构的(Sm_0.5Gd_0.2Nd_0.3)₂(Hf_0.3Ce_0.7)₂O₇复合氧化物。其显微组织结构致密,晶界清晰无其他相存在。由于复杂的元素组成和较大的原子量,其热导率明显低于7YSZ和Sm₂Ce₂O₇。其较低的热膨胀系数则归因于B位离子较小的离子半径,但其热膨胀系数依然满足热障涂层的要求。     

铈基介孔金属有机骨架固定化酶的构建及催化性能

金属有机骨架(MOF)材料由于其孔隙率高、比表面积大以及具有发达的内联通孔道结构等优点,可以作为优良的生物分子固定化载体。通过表面活性自组装策略制备了铈基介孔MOF(Ce-MOF-F),表征结果表明,该材料有大的比表面积和呈辐射状的介孔孔道结构。以其为载体、南极假丝酵母脂肪酶B(CALB)为模型酶,通过物理吸附法制备了生物催化剂CALB@Ce-MOF-F,对该固定化酶的酶载量和催化性能进行了研究。在优化条件下,CALB的负载量为162.0mg/g载体,水解活性为899.1U/g蛋白。与游离CALB相比,CALB@Ce-MOF-F表现出对高温、酸碱和有机溶剂等有更强的耐受性;将Ce-MOF-F用于多种酶的固定化,研究其作为载体的普适性,结果表明,介孔Ce-MOF-F对洋葱伯克氏菌脂肪酶(BCL)和漆酶有良好的固定效果,可以作为良好载体,并能对酶起到较好的保护作用。     

团簇Au/CeO2的制备及其催化CO氧化反应构效关系的研究

负载型Au催化剂因其在诸多反应过程中的高催化活性而备受研究者关注.然而针对负载型催化剂中Au物种结构的有效调控,以及催化过程中真实构-效关系的探索一直充满了挑战.用CeO₂为Au物种担载基底,通过简单煅烧处理引起的CeO₂结构变化,进而实现Au/CeO₂之间界面作用力的调控.此研究发现Au纳米颗粒中Au⁰物种具备更为高效的催化室温CO氧化活性,结合多种原位表征分析,其室温条件下催化转化效率更依赖于CO吸附能力.而相比于单原子Au₁和纳米Au颗粒,所制备的团簇Au/CeO₂催化剂在较高温度(>50℃)展现出优异的催化CO氧化反应性能.随着温度升高,催化剂表界面O参与的MvK反应路径更易发生,因此具有更多表界面活性O物种和Au^δ+位点的团簇Au/CeO₂催化剂展现出最为优异的催化CO氧化性能.这些发现为高效负载型Au催化剂的制备提供了新思路并深化了对Au/CeO₂催化作用机制的理解.     

Determination of lanthanum and cerium in cmsx-4 nickel-based superalloys by inductively coupled plasma mass spectrometryEI北大核心CSCD

CMSX-4 is the second-generation nickel-based single crystal superalloy used widely in the world. The oxidation resistance and corrosion resistance of CMSX-4 alloy can be improved by adding trace lanthanum (La), cerium (Ce) and other rare earth elements. A method for the simultaneous determination of La and Ce in CMSX-4 nickel-based superalloy by wet dissolution-inductively coupled plasma mass spectrometry was established. The sample was heated and dissolved under normal pressure by aqua regia and hydrofluoric acid, and the interference of fluorine ion was eliminated by using perchloric acid. The amount of dissolved acid and the digestion conditions were optimized. The limits of detection were 0.23 μg/g for La and 0.85 μg/g for Ce under optimized conditions. The spiked recoveries were 95.0%–98.9% with the relative standard deviations of 1.3%–3.9%, which can meet the requirements of accurate and rapid determination of La and Ce in CMSX-4 nickel-based superalloy. © 2023, Youke Publishing Co.,Ltd. All rights reserved.     

铈(Ⅲ)-巴比妥钠配合物催化双(对硝基苯基)磷酸酯水解性能

研究了Ce(Ⅲ)离子与巴比妥钠形成的配合物对双(对硝基苯基)磷酸酯(BNPP)的催化水解作用。 结果表明, Ce(Ⅲ)与巴比妥钠形成的配合物对BNPP的水解具有很高的催化活性,可使BNPP水解速率提高至自发水解时的1.52×10⁸倍。 体系的pH值和温度对催化水解反应的影响,发现在温度为25 ℃和pH值为8.50的条件下,催化效果最佳。     

七水三氯化铈-碘化钠/二氧化硅-壳聚糖催化剂的制备及其在脱保护反应中的应用

分别以Y沸石、活性碳和二氧化硅-壳聚糖(SiO₂-CS)为载体、利用浸渍法制备了一系列负载型七水三氯化铈-碘化钠(CeCl₃·7H₂O-NaI)催化剂,考察了它们在叔丁基苯基醚的脱保护反应中的催化性能。 结果表明,SiO₂-CS为载体的催化剂呈现出良好的催化性能和较高的稳定性。 另外,在中性条件下,SiO₂-CS负载CeCl₃·7H₂O-NaI催化剂在叔丁基醚及1,3-二硫缩醛脱保护反应中呈现出较高的催化活性,从而避免使用强酸和强碱。     

多金核二氧化铈空心球用于硝基苯酚催化加氢

催化剂的微观结构在催化还原反应、有机物氧化反应及有机物转化反应中起着关键作用。本文利用无模板方法合成了多金核中空二氧化铈微球催化剂。将制备好的二氧化铈中空微球浸渍到一定浓度的氯金酸溶液中,然后多次洗涤除去表面吸附的氯金酸离子,最后通过硼氢化钠还原制成中空氧化铈微球包覆的多金核的核壳结构催化剂。将该核壳结构材料用于硝基苯酚加氢反应与金纳米粒子及氧化铈微球相比,多金核中空二氧化铈核壳结构表现出优越的活性和稳定性。通过这种浸渍洗涤再还原的简单方法合成的多金核二氧化铈催化剂有望应用于生物医药和能源环境等领域。