以尿素替代水为溶剂,采用改良的尿素水解法制备不同结构的CeOHCO3和CeO2,并运用N2吸附-脱附、X射线衍射、H2程序升温还原、O2程序升温脱附、X射线光电子能谱、扫描电镜及甲烷燃烧反应对CeO2催化剂进行表征和催化性能测试.结果表明,CeO2催化性能和前驱体CeOHCO3的晶相结构(六方相或八面体相)存在直接关系.与以八面体为前驱体制得的颗粒状CeO2相比,以六方相为前驱体制得的棒状CeO2具有比表面积大、氧化还原能力强、表面氧空缺浓度高以及催化甲烷燃烧活性高的特点.
Abstract:A modified hydrothermal process method based on using urea instead of water as the solvent was used to prepare CeOHCO3.Pure CeOHCO3 with a single crystalline structure was produced by varying the experimental conditions.CeO2 particles obtained from these CeOHCO3 precursors were tested for CH4 oxidation.The temperatures for 90％ methane conversion were 604 and 647 ℃ for CeO2 catalysts obtained from hexagonal and orthorhombic CeOHCO3,respectively,indicating that the CeO2 catalyst from hexagonal CeOHCO3 (CeO2-A) was more active than that from the orthorhombic form (CeO2-D).The specific surface area and pore volume of CeO2-A were 45 m2/g and 0.35 cm3/g,respectively,which were higher than those of CeO2-D.H2-TPR showed a much lower reduction temperature and enhanced reducibility with CeO2-A.XPS and O2-TPD results demonstrated there were more oxygen vacancies on the surface of CeO2-A than on CeO2-D,which implied increased oxygen mobility.The CeOHCO3-strumcture dependent activity was investigated and found to originate from the morphologies of the CeOHCO3 precursors.Hexagonal CeOHCO3 had a rod-like shape while orthorhombic CeOHCO3 had a sphere-like morphology.After calcination,the obtained CeO2 had the morphology of the precursor.The difference in morphology gave CeO2 catalysts with different texture,structure,reducibility,and thus catalytic activity.
参考文献
| [1] | Zhang Y J;Gao M R;Han K D;Fang Z Y Yin X B Xu Z Y .[J].Journal of Alloys and Compounds,2009,474:598. |
| [2] | Zhang D S;Niu F H;Yan T T;Shi L Y Du X J Fang J H .[J].Applied Surface Science,2011,257:10161. |
| [3] | 李斌,李士杰,王颖霞,李能,张婉静,林炳雄.CeO2和γ-Al2O3混合氧化物的共生共存效应[J].催化学报,2010(05):528-534. |
| [4] | Zhao D L;Yang Q;Han Z H;Sun F Y Tang K B Yu F .[J].Solid State Sciences,2008,10:1028. |
| [5] | Mamontov E;Egami T;Brezny R;Koranne M Tyagi S .[J].Journal of Physical Chemistry B,2000,104:11110. |
| [6] | Wang H C;Lu C H .[J].Materials Research Bulletin,2002,37:783. |
| [7] | Bumajdad A;Eastoe J;Mathew A .Cerium oxide nanoparticles prepared in self-assembled systems[J].Advances in colloid and interface science,2009(0):56-66. |
| [8] | Zhou H P;Zhang Y W;Si R;Zhang L S Song W G Yan C H .[J].J Phvs Chem C,2008,112:20366. |
| [9] | Han Z H;Guo N;Tang K B;Yu S H Zhao H Q Qian Y T .[J].Journal of Crystal Growth,2000,219:315. |
| [10] | Cui M Y;He J X;Lu N P;Zheng Y Y Dong W J Tang W H Chen B Y Li C R .[J].Materials Chemistry and Physics,2010,121:314. |
| [11] | Yu J C;Zhang L;Lin J .[J].Journal of Colloid and Interface Science,2003,260:240. |
| [12] | Pan, CS;Zhang, DS;Shi, LY .CTAB assisted hydrothermal synthesis, controlled conversion and CO oxidation properties of CeO2 nanoplates, nanotubes, and nanorods[J].Journal of Solid State Chemistry,2008(6):1298-1306. |
| [13] | Li X D;Li J G;Huo D;Xiu Z M Sun X D .[J].Journal of Physical Chemistry C,2009,113:1806. |
| [14] | Guo Z Y;Du F L;Cui Z L .[J].Materials Chemistry and Physics,2009,113:53. |
| [15] | Sun C W;Li H;Wang Z X;Chcn L Q Huang X J .[J].Chemistry Letters,2004,33:662. |
| [16] | Mai H X;Sun L D;Zhang Y W;Si R,Feng W,Zhang H P.Liu H C,Yah C H .[J].Journal of Physical Chemistry B,2005,109:24380. |
| [17] | Sun M J;Zou G J;Xu S;Wang X L .[J].Materials Chemistry and Physics,2012,134:912. |
| [18] | Chen S F;Yu S H;Yu B;Ren L,Yao W T,C(o)l1fen H .[J].Chemistry-A European Journal,2004,10:3050. |
| [19] | Fu C;Li R X;Tang Q;Li C Q Yin S Sato T .[J].Research on Chemical Intermediates,2011,37:319. |
| [20] | Qiao D S;Lu G Z;Mao D S;Guo Y Guo Y L .[J].Journal of Materials Science,2011,46:641. |
| [21] | Zhou K B;Wang X;Sun X M;Peng Q Li Y D .[J].Journal of Catalysis,2005,229:206. |
| [22] | Li S Q;Wang X L .[J].Catalysis Communications,2007,8:410. |
| [23] | Mi(s)ta W;Malecka M A;Kepifiski L .[J].Applied Catalysis A:General,2009,368:71. |
| [24] | 单文娟,刘畅,郭红娟,杨利华,王晓楠,冯兆池.0,1,3维CeO2的可控制备及CuO/CeO2催化剂上CO氧化反应[J].催化学报,2011(08):1336-1341. |
| [25] | Cabús-Llauradó M C;Cesteros Y;Medina F;Salagre P Sueiras J E .[J].Microporous and Mesoporous Materials,2007,100:167. |
| [26] | Liang Q;Wu X D;Weng D;Xu H B .[J].Catalysis Today,2008,139:113. |
| [27] | Ji P F;Zhang J L;Chen F;Anpo M .[J].JPhys Chem C,2008,112:17809. |
| [28] | Ho C;Yu J C;Kwong T;Mak A C Lai S .[J].Chemistry of Materials,2005,17:4514. |
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