制备参数对高比表面积介孔催化剂La-Co-Zr-O结构与性能的影响  

Effects of Preparation Parameters on Structures and Properties of Mesoporous La-Co-Zr-O Catalysts with High Specific Surface Area

作　　者：邹志强[1] 孟明[1] 李倩[1] 查宇清[1] 

机构地区：[1]天津大学化工学院催化科学与工程系,天津300072

出　　处：《无机化学学报》2007年第7期1213-1219,共7页Chinese Journal of Inorganic Chemistry

基　　金：国家高技术研究发展计划(863计划)(No.2006AA06Z348);国家自然科学基金资助项目(No.20676097)

摘　　要：采用双表面活性剂模板(十六烷基三甲基溴化铵和聚乙二醇辛基苯基醚的混合物)分解法制备了不同原子比(nLa+nCo)/(nLa+nCo+nZr)和不同温度焙烧的系列介孔混合氧化物催化剂La-Co-Zr-O。运用XRD、N2吸附/脱附、XPS和H2-TPR等技术对催化剂进行了表征,并以CO和C3H8氧化为模型反应,考察了组分配比和焙烧温度等参数对催化剂催化性能的影响。比表面积和孔径测试结果表明,样品具有很高的比表面积(108～266m2·g-1)和分布集中的孔径(3.4～3.9nm),Zr含量较高的样品比表面积较大。XRD结果表明,样品中的活性组分钴物种主要以Co3O4形式存在;XPS和H2-TPR结果表明,样品中可还原的晶格氧的数量、活动度以及表面钴原子浓度均与催化剂对CO和C3H8的氧化性能密切相关。原子比为0.5的样品中,较多的晶格氧易于在相对低温下还原;而原子比为0.7的样品表面钴原子浓度较高,这使得两样品均表现出较高的催化活性。经650℃焙烧的样品仍保持较高的比表面积(108m2·g-1)和分布集中的介孔孔径(最可几孔径约3.8nm),且催化活性下降幅度也很小,表明该系列介孔催化剂具有优良的抗烧结能力和介孔热稳定性。A series of mesoporous La-Co-Zr-O mixed oxide catalysts with various （nLa＋nCo）/（nLa＋nCo＋nZr） ratios and different calcination temperatures were prepared by decomposition of dual-organic templates of cetyhrimethyl-ammonium bromide （CTAB） and p-octyl polyethylene glycol phenyl ether （OP）. The catalysts were characterized by XRD, XPS, N2 adsorption/desorption and H2.TPR. The effects of component ratios and calcination temperatures on the catalytic properties were investigated using CO and C3H8 oxidation as model reactions. The results of N2 adsorption/desorption and pore size distribution measurements show that the samples possess very large specific surface area （108～266m^2·g^-1） and narrow pore size distribution （3.4～3.9nm）. The catalyst containing higher content of Zr shows larger specific surface area. The results of XRD indicate that the active component cobalt species in samples mainly exist as Co3O4. The results of H2-TPR and XPS indicate that the amount and mobility of the reducible lattice oxygen in samples and the concentration of surface cobalt atoms are closely relevant to the activities of the catalysts. There are more reducible lattice oxygen species for the sample with atomic ratio of 0.5 at low temperature than in other samples, and there are more surface cobalt atoms for the sample with atomic ratio of 0.7, thus making the two samples exhibited excellent catalytic oxidation activity. After calcination at 650℃, the sample still keeps high specific surface areas （108m^2·g^-1） and very narrow pore diameter distribution （the most probable pore size 3.83 nm） with a slightly decreased activity, indicating a very good ability ofsintering resistance and high thermal stability of mesoporous structures for this series of catalysts.

关 键 词：La-Co-Zr-O催化剂 CO氧化 C3H8氧化 十六烷基三甲基溴化铵 聚乙二醇辛基苯基醚 

分 类 号：O643[理学—物理化学]