title: Highly coke-resistant ni nanoparticle catalysts with minimal sintering in dry reforming of methane.
abstract: Nickel catalysts are typically used for hydrogen production by reforming reactions. Reforming methane with carbon dioxide, called dry reforming of methane (DRM), is a good way to produce hydrogen or syngas (a mixture of hydrogen and carbon monoxide) from two notable greenhouse gases. However, Ni catalysts used for DRM suffer from severe coke deposition. It has been known that small Ni nanoparticles are advantageous to reduce coke formation, but the high reaction temperature of DRM (800 °C) inevitably induces aggregation of the nanoparticles, leading to severe coke formation and degraded activity. Here, we develop highly coke-resistant Ni catalysts by immobilizing premade Ni nanoparticles of 5.2 nm in size onto functionalized silica supports, and then coating the Ni/SiO2 catalyst with silica overlayers. The silica overlayers enable the transfer of reactants and products while preventing aggregation of the Ni nanoparticles. The silica-coated Ni catalysts operate stably for 170 h without any degradation in activity. No carbon deposition was observed by temperature programmed oxidation (TPO), transmission electron microscopy (TEM), X-ray diffraction (XRD), and Raman spectroscopy. The Ni catalysts without silica coating show severe sintering after DRM reaction, and the formation of filamentous carbon was observed. The coke-resistant Ni catalyst is potentially useful in various hydrocarbon transformations.
authors.affiliation: Department of Chemical and Biomolecular Engineering, Yonsei University, Seoul, 120-749 (South Korea), Fax: (+82) 2-312-6401.
authors.forename: Joung Woo
authors.initials: JW
authors.lastname: Han
authors.forename: Chanyeon
authors.initials: C
authors.lastname: Kim
authors.forename: Jun Seong
authors.initials: JS
authors.lastname: Park
authors.forename: Hyunjoo
authors.initials: H
authors.lastname: Lee
mesh_terms: D002384:Catalysis; D003077:Coke; D053768:Metal Nanoparticles / Q000737:chemistry*; D008697:Methane / Q000737:chemistry*; D009532:Nickel / Q000737:chemistry*; D012822:Silicon Dioxide / Q000737:chemistry
chemical_list: D003077:Coke; D012822:Silicon Dioxide; D009532:Nickel; D008697:Methane
keywords: coking; heterogeneous catalysis; methane; nickel; reforming