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.     

氯乙烯与四氯化碳调聚反应生成1,1,1,3,3-五氯丙烷研究进展

叙述了以氯乙烯(CH2=CHCl)和四氯化碳(CCl4)为原料,通过调聚反应合成1,1,1,3,3-五氯丙烷(HCC-240fa)的研究进展,比较了Fe系、Cu系催化剂的调聚反应合成HCC-240fa的性能,Cu系催化剂的性能优于Fe系催化剂。认为进一步提高Cu系催化剂的性能是以后研究的重点,还应该注意催化剂的回收、原料的节约利用、提高原料的转化率、产物HCC-240fa的选择性,及其防止催化剂流失而对环境造成的污染等问题。     

Characterization and Preparation of Ce-Zr-O Solid Solution

ＣｅｒｉｕｍｏｘｉｄｅｗｉｔｈＣａＦ2 ｓｔｒｕｃｔｕｒｅｉｓｃｕｒ ｒｅｎｔｌｙｂｅｉｎｇｕｓｅｄａｓａｐｒｏｍｏｔｅｒｉｎｏｘｉｄａｔｉｏｎ .ＴｈｅｃａｐａｂｉｌｉｔｉｅｓｏｆｔｈｅｒｅｄｏｘｃｏｕｐｌｅＣｅ4 Ｃｅ3 ａｒｅｓｔｒｏｎｇｌｙｅｎｈａｎｃｅｄｉｆｏｔｈｅｒｅｌｅｍｅｎｔｉｓｉｎｔｒｏ ｄｕｃｅｄｉｎｔｏＣｅＯ2 ｌａｔｔｉｃｅｂｙｆｏｒｍｉｎｇｓｏｌｉｄｓｏｌｕ ｔｉｏｎ .ＳｅｖｅｒａｌａｐｐｒｏａｃｈｅｓｈａｖｅｂｅｅｎｕｓｅｄｔｏｐｒｅｐａｒｅＣｅＯ2 ＺｒＯ2 ｍｉｘｅｄｏｘｉｄｅ…     

A comparative study of formaldehyde and carbon monoxide complete oxidation on MnOx-CeO2 catalysts

MnOx-CeO2 composite catalysts were prepared by a coprecipitation method and tested for formaldehyde (HCHO) and carbon monoxide (CO) oxidation. X-ray photon spectroscopy (XPS) results indicated that the average oxidation state of surface Mn species in CeMn composite catalyst was higher compared to the pure MnOx. The enhancement of reactivity for HCHO oxidation was due to the activation of the lattice oxygen species in MnOx by the addition of CeO2, which was confirmed by the H2 temperature programmed reduction (H2-TPR) results. The remarkable enhancement of reactivity for CO oxidation by the addition of CeO2 was due to the active oxygen species generated on the CeO2 surface which directly participated in the reaction.     

助剂Ba对Pd/Al_2O_3和Pt/Al_2O_3催化剂的C1-C3烷烃催化燃烧性能的影响

通过浸渍法制备了Al_2O_3负载的Pd和Pt催化剂,考察催化剂的甲烷、乙烷和丙烷催化燃烧活性,以及助剂Ba对催化性能的影响。对于Pd/Al_2O_3催化剂,加入Ba使活性物种PdO颗粒变大和还原温度升高,形成更稳定的PdO活性物种,是Pd-Ba/Al_2O_3催化剂活性提升的主要原因。对于Pt/Al_2O_3催化剂,加入Ba助剂使活性物种Pt0含量降低,PtO_x与Al_2O_3载体相互作用增强,使PtO_x物种更难被还原为Pt~0,导致Pt-Ba/Al_2O_3催化剂活性降低。Pd和Pt催化剂催化烷烃氧化反应活性规律一致:丙烷乙烷甲烷。Pd/Al_2O_3催化剂有利于C—H键活化,Pt/Al_2O_3催化剂有利于C—C键活化。Pt/Al_2O_3催化剂对C1-C3烷烃氧化活性的差别明显大于Pd/Al_2O_3催化剂。Pt/Al_2O_3催化剂对碳比例高的烷烃活性更高。     

Mn-Fe-O/NM燃烧催化剂的研究

本文考察了以天然丝光沸石为载体,Mn、Fe为活性组分的Mn-Fe-O/NM催化剂对丙酮、甲苯的氧化活性,并与Pt/NM催化剂进行了对比。实验结果表明,双组分催化剂活性高于单组分催化剂。Mn/Fe相对原子比在3/1、负载量0.1mol/100gNM时活性最佳。对含氧有机物如丙酮、乙酸乙酯Mn-Fe-O/NM催化剂氧化活性高于Pt/NM催化剂,而对芳烃类有机物甲苯则相反。     

氧化铝颗粒表面A型分子筛膜的合成和表征

在氧化铝颗粒表面预涂分子筛晶种的基础上,水热晶化合成A型分子筛膜.用X射线衍射、扫描电镜和Raman光谱对复合体的物相结构、表面形貌和表面物种结构进行表征.初步探讨了粒状基底上分子筛膜的合成条件,研究了预涂晶种和合成次数对分子筛膜的影响.结果表明:增加合成次数,能有效改善分子筛膜的质量.二次合成后,颗粒Al2O3表面完全被致密均匀的A型分子筛膜覆盖,膜厚仅为15μm,三次合成的分子筛膜膜厚增至50 pm.     

Cu-Mn复合氧化物催化剂的制备和VOCs催化燃烧性能

以堇青石为载体,制备了堇青石负载Cu-Mn-Ag过渡金属氧化物催化剂.对其进行了甲苯催化燃烧活性评价,并采用TPR技术对催化剂进行了表征研究.探索了制备方法、助剂对催化剂的性能影响.表明Ag的引入有利于提高催化剂的甲苯的催化燃烧性能,而K的引入则抑制了其催化性能.     

纳米Ce0.9Cu0.1O2-δ固溶体的制备、表征和CO低温氧化性能

采用改进的柠檬酸溶胶-凝胶法(即前驱体先在N2气氛下高温预处理)制备了高比表面积纳米Ce0.9Cu0.1O2-δ固溶体。采用XRD、TEM和Raman等对催化剂进行表征,并考察了它们的低温CO氧化性能。研究结果表明,改进的柠檬酸溶胶-凝胶法可以制得晶相比较完整的Ce0.9Cu0.1O2-δ固溶体,晶粒小于10 nm,明显小于常规方法制得的样品。随着样品焙烧温度的提高,表征氧缺位的600 cm-1左右Raman峰的位置向高波数方向迁移。采用改进方法制得的Ce0.9Cu0.1O2-δ固溶体具有更高的CO氧化活性,其原因归结为晶粒的减小,容易形成氧缺位和表面高分散CuO的增加,从而促进了CO的氧化。     

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。