CO and C3H8 total oxidation over Pd/La-Al2O3 catalysts： Effect of calcination temperature and hydrothermal treatment

A series of Pd/La-Al2O3（PLA） catalysts with La-Al2O3（LA） support calcined at different temperatures（500, 700, 900 and 1050 oC） were prepared using an incipient wetness impregnation method. The activity of the fresh and hydrothermally aged PLA catalysts were tested for total oxidation of CO and C3H8. The activity of the fresh PLA catalysts for CO and C3H8 oxidation increased with increasing calcination temperature of the support, while the activities of the aged catalysts declined and became essentially the same. CO chemisorption results revealed that the suppressed activities of the aged catalysts were mainly due to the decline of palladium dispersion. The turnover frequency（TOF） of CO oxidation increased with increasing reduction ability of the catalysts, with a fresh catalyst calcined at 1050 oC having the highest value（0.048 s–1）. However, the TOF of C3H8 total oxidation was affected by not only the redox properties of catalysts but also the size of Pd particle, and large Pd particles possessed higher TOF value of C3H8 oxidation, with the highest value（0.125 s–1） being obtained on an aged catalyst calcined at 500 oC.     

挥发性有机物燃烧催化剂的研究进展

挥发性有机物（VOCs）是主要大气污染物质，也是形成PM_2.5和臭氧的重要前体。强化挥发性有机物控制，是改善大气环境的重要途径。催化燃烧（氧化）被认为是去除VOCs最有效的方式之一，本文综述了VOCs催化燃烧常用的贵金属催化剂、非贵金属催化剂。其中，贵金属催化剂主要包括基于Pd、Pt、Ru等的催化剂，非贵金属催化剂主要包括Mn、Co、Ce、Zr等的氧化物，通常贵金属催化剂具有比非贵金属更高的氧化活性和稳定性，但对于含氮VOCs非贵金属催化剂（Mn、Cu）具有更好的氮气选择性，Cr基催化剂对于含氯VOCs燃烧具有更好的效果。此外，还重点讨论了载体、分散度、催化剂制备方法对贵金属催化剂性能的影响，并对发展VOCs氧化催化剂的研究提出了展望。     

一种基于线特征约束的无人机双目视觉SLAM算法

为了解决点特征SLAM算法在低纹理环境中精度下降的问题,提出了一种基于线特征约束的无人机双目视觉SLAM算法。首先,将双目相机观测线特征分为单目相机在两帧下观测、双目相机在两帧下观测、双目相机在一帧下观测3种情况;然后,计算了3种情况下的残差块和雅可比矩阵;最后,利用所提线特征约束改进了VINS-Fusion算法。在EuRoC数据集上进行实验验证,结果表明提出的算法在数据集半数以上的场景中都有良好的表现,相较于改进前的VINS-Fusion算法定位精度平均提升13.2%。     

负载型CeO2/OMS -2催化剂对VOCs的催化氧化性能

采用回流法合成了OMS -2,同时以OMS -2为载体,采用浸渍法负载CeO2制备了Ce/OMS-2催化剂,运用X射线衍射、拉曼光谱、BET、H2 - TPR和NH3 - TPD等方法对催化剂进行表征,并考察CeO2/OMS -2催化剂催化氧化二氯甲烷和乙酸乙酯的性能.结果表明,CeO2的加入并未改变OMS -2较好的八面体分子筛结构,CeO2的晶粒很小且以高分散的形式存在;负载CeO2的OMS -2催化剂比表面积都有增大趋势;随着CeO2负载量的增加,低温和高温的还原峰都先向低温方向偏移再向高温方向偏移;随着CeO2负载量的增加,高温处强酸性峰先向低温方向偏移再向高温方向偏移.反应活性结果表明,CeO2/OMS -2催化剂活性比载体OMS -2的活性好,随着铈负载量的增加,催化活性先升高再降低,其中,CeO2负载质量分数为1.0％(1.0Ce/OMS -2)时催化剂效果最好,这可能是由于铈的加入活化了OMS -2中的氧,影响了整体催化剂的酸性,进而影响反应性能.     

负载型CeO_2/OMS-2催化剂对VOCs的催化氧化性能

采用回流法合成了OMS-2,同时以OMS-2为载体,采用浸渍法负载CeO_2制备了Ce/OMS-2催化剂,运用X射线衍射、拉曼光谱、BET、H_2-TPR和NH_3-TPD等方法对催化剂进行表征,并考察CeO_2/OMS-2催化剂催化氧化二氯甲烷和乙酸乙酯的性能。结果表明,CeO_2的加入并未改变OMS-2较好的八面体分子筛结构,CeO_2的晶粒很小且以高分散的形式存在;负载CeO_2的OMS-2催化剂比表面积都有增大趋势;随着CeO_2负载量的增加,低温和高温的还原峰都先向低温方向偏移再向高温方向偏移;随着CeO_2负载量的增加,高温处强酸性峰先向低温方向偏移再向高温方向偏移。反应活性结果表明,CeO_2/OMS-2催化剂活性比载体OMS-2的活性好,随着铈负载量的增加,催化活性先升高再降低,其中,CeO_2负载质量分数为1.0%(1.0Ce/OMS-2)时催化剂效果最好,这可能是由于铈的加入活化了OMS-2中的氧,影响了整体催化剂的酸性,进而影响反应性能。     

捆绑式气动冲击锤嵌岩施工技术

气动冲击锤在国内外已被广泛用于硬岩地质条件下的工程施工，捆绑式气动冲击锤，可以直接一次性完成较单体冲击锤直径大得多的混凝土嵌岩灌注桩。文章介绍了两个工程实例：（1）采用捆绑式气动冲击锤对基岩直接出露的地基成孔，与爆破成孔相比，成孔规则，孔深相对较浅就能满足设计要求，成桩速度快。（2）用振动压管机压管、长螺旋钻取土和捆绑式气动冲击锤破岩的联合工法，可有效地解决桩长在20m左右嵌岩桩成孔难的问题。     

La2O3的添加方式对Al2O3热稳定性的影响

采用3种不同添加方式制备La₂O₃改性的Al₂O₃材料La-Al₂O₃。La-Al₂O₃分别经500 ℃、1 000 ℃和1 200 ℃焙烧,采用物理吸附、X射线衍射和荧光光谱等对高温处理的La-Al₂O₃进行比表面积和结构表征。结果表明,La₂O₃的添加能有效抑制Al₂O₃在高温条件下向热力学稳定态α-Al₂O₃转变,同时提高高温处理后La-Al₂O₃比表面积,使Al₂O₃热稳定性得到明显提高。在3种La₂O₃添加方式中,La(NO₃)₃浸渍法效果最为显著,制得的La-Al₂O₃(N)材料经1 200 ℃焙烧4 h的比表面积为30 m²·g^－1,是未经改性的Al₂O₃样品经同等温度焙烧比表面积的2.2倍。     

薏苡仁油对小鼠免疫功能影响的研究

探讨薏苡仁油对小鼠免疫功能的影响。分别以低、中、高剂量薏苡仁油(0.17、0.33、1.00 g/kg)和食用植物油连续经口灌胃ICR小鼠30 d,测定胸腺指数与脾指数,并进行脾淋巴细胞转化实验、迟发性变态反应实验、血清溶血素实验和抗体生成细胞检测、碳廓清实验、腹腔巨噬细胞吞噬鸡红细胞实验和NK细胞活性实验。结果表明:高剂量(1.00 g/kg)组能显著增强脾淋巴细胞增殖能力(以刀豆蛋白A(ConA)诱导)和迟发性变态反应(以二硝基氟苯(DNFB)诱导),升高小鼠血清溶血素水平,增强小鼠抗体生成能力和NK细胞活性。证明薏苡仁油具有增强免疫力作用。     

Preparation and characterizations of Ce-Cu-O monolithic catalysts for ethyl acetate catalytic combustion

Ce-Cu-O monolithic catalysts were prepared by using Ce0.9Cu0.1O1.9 solid solution or nitrate as precursors,and their catalytic performance for the combustion of ethyl acetate were studied.The catalysts calcined at a low temperature showed high catalytic activities.When calcined at high temperatures,the catalyst with Ce0.9Cu0.1O1.9 solid solution as precursor remained a high activity,while the catalyst with metal nitrates as precursors exhibited a suppressed reactivity.Therefore,the catalyst prepared with th...     

Palladium catalysts supported on novel CexY1-xO washcoats for toluene catalytic combustion

Novel CexY1-xO washcoats adhered on the cordierite honeycomb, used as supports for Pd catalysts, were prepared by an impregnation method. It was fotmd that the CexY1-xO washcoats had better adhesion and higher adsorption efficiency of H2PdCl4, and the optimal component of the washcoat was Ce0.8Y0.2O. Model reaction of catalytic combustion of toluene was chosen to evaluate the performance of the developed Pd/CexY1-xO/substrate catalysts. The results showed that the catalytic performance of the Pd/CexY1-xO/substrate catalysts depended on the component of the washcoats, with the Pd/Ce0.8Y0.2O/substrate catalyst giving the best catalytic activity and thermal stability.