title: Hierarchical copper-decorated nickel nanocatalysts supported on La2O3 for low-temperature steam reforming of ethanol.
abstract: Copper/nickel nanocatalysts with a unique morphology were prepared by thermal reduction of a perovskite LaNix Cu1-x O3 precursor (x=1, 0.9, and 0.7). During thermal reduction, copper was first reduced and reacted with lanthanum to form metastable Cu5 La and Cu13 La. When the thermal reduction temperature was increased, the perovskite decomposed to Ni and La2 O3 , CuLa alloys disappeared, and Cu deposits on Ni nanoparticles were generated, thereby forming Cu/Ni nanocatalysts with hierarchical structures. Nanosized nickel, decorated with copper and supported on La2 O3 , could be produced at 520-550 °C. The steam reforming of ethanol was used as a model reaction to demonstrate the catalytic capability of the materials formed. The hierarchical structure of the Cu/Ni/La2 O3 catalysts confers synergetic effects that greatly favor the dehydrogenation of ethanol and which break the C-C bond to produce a higher yield of hydrogen at a low reaction temperature, whereas La2 O3 provides the required stability during the reaction. The reaction at 290 °C achieved almost 100 % conversion with a hydrogen yield reaching 2.21 molH2  mol(-1) EtOH thus indicating that this special structural feature can achieve high activity for the SRE at low temperatures. The proposed synthesis of nanocatalysts appears to be a good way to generate oxide-supported hierarchically structured nanoparticles that can also be applied to other reactions catalyzed by a heterogeneous metal oxide system.
authors.affiliation: Department of Chemical Engineering, National Taiwan University of Science and Technology, 43, Keelung Road, Taipei 106 (Taiwan).
authors.forename: Jyong-Yue
authors.initials: JY
authors.lastname: Liu
authors.forename: Wei-Nien
authors.initials: WN
authors.lastname: Su
authors.forename: John
authors.initials: J
authors.lastname: Rick
authors.forename: Sheng-Chiang
authors.initials: SC
authors.lastname: Yang
authors.forename: Ju-Hsiang
authors.initials: JH
authors.lastname: Cheng
authors.forename: Chun-Jern
authors.initials: CJ
authors.lastname: Pan
authors.forename: Jyh-Fu
authors.initials: JF
authors.lastname: Lee
authors.forename: Bing-Joe
authors.initials: BJ
authors.lastname: Hwang
mesh_terms: D003300:Copper / Q000737:chemistry*; D000431:Ethanol / Q000737:chemistry*; D007811:Lanthanum / Q000737:chemistry*; D053768:Metal Nanoparticles / Q000737:chemistry*; D009532:Nickel / Q000737:chemistry*; D010087:Oxides / Q000737:chemistry*; D013227:Steam; D013696:Temperature
chemical_list: D010087:Oxides; D013227:Steam; D000431:Ethanol; C103829:lanthanum oxide; D007811:Lanthanum; D003300:Copper; D009532:Nickel
keywords: copper; heterogeneous catalysis; lanthanides; nanoparticles; nickel