Rimma Bunina

A role of surface nitrite and nitrate complexes in NOx selective catalytic reduction by hydrocarbons under oxygen excess

NO adsorption over three types of catalytic systems, such as cation-exchanged zeolites, transition metal oxides supported on γ-Al2O3, and partially stabilised tetragonal ZrO2 (PSZ) was studied by using the TPD method. NO forms several surface complexes having different desorption temperatures. TPD results compared with catalytic properties of these systems in the selective reduction of NOx by propane under oxygen excess showed that strongly bound nitrites and nitrates appeared to be true intermediates in this reaction.

Honeycomb-supported perovskite catalysts for high-temperature processes

Pechini route [US Patent No. 3,330,697 (1967)] was used for supporting perovskite-like systems on thin-wall corundum honeycomb support to prepare catalysts for high-temperature processes of methane combustion and selective oxidation into syngas. In this preparation, the surface of corundum monoliths walls was shown to be covered by strongly adhering porous perovskite layer formed by rounded crystals. At high temperatures when pore diffusion is expected to affect catalysts performance in fast reactions, this spatial distribution of the active component could be attractive. In the kinetically controlled region of methane oxidation, samples prepared via Pechini route possess activity comparable with that of samples made via support wet impregnation with mixed nitrate solutions, when an active component is uniformly distributed across the wall thickness. Corundum-supported lanthanum manganite and ferrite are the most active in the reaction of methane combustion, while its selective oxidation into syngas effectively proceeds on supported lanthanum cobaltite and nickelates. Corundum-supported perovskites are more thermally stable as compared with those on γ-alumina support.

Cu, Co, Ag-Containing Pillared Clays as Catalysts for the Selective Reduction of NOx by Hydrocarbons in an Excess of Oxygen

Thermally stable Al- and Zr-PILC loaded with copper and cobalt cations and silver nanoparticles were synthesized. The structural and surface features of these nanosystems were studied and compared with those of bulk analogs – partially stabilized ZrO2 loaded with the same active components. Specificity of the catalytic properties of nanocomposites in SCR of NOx by propane, propylene and decane in the excess of oxygen appears to be determined both by distribution of active components on the catalytic surface and degree of their interaction with supports. Formation of ads.-NOx, nitroxyl-hydrocarbon CxHyNO2⋅ and isocyanate NCO intermediates was observed by ESR and IR spectroscopy in situ.

Study of synthesis gas production over structured catalysts based on LaNi(Pt)Ox- and Pt(LaPt)- CeO2-ZrO2 supported on corundum

Abstract Study of partial oxidation of methane (POM), steam (SR), authothermal (AR) and dry (DR) reforming of methane over catalysts containing LaNiO3 (pure or promoted by Pt) or LaPtO x /CeO 2 -ZrO 2 supported on the fragments of corundum monolith reveals that the most effective catalysts contain LaNiO 3 and LaPtO x with La excess. The reduction pretreatment as well as addition of Pt to LaNiO x facilitates the formation of syngas at a lower temperature, furthermore, Pt favors a high catalyst stability preventing catalyst coking.

A Sol–Gel Derived CuOx/Al2O3–ZrO2 Catalyst for the Selective Reduction of NO by Propane in the Presence of Excess Oxygen

Copper catalysts supported on alumina-doped zirconia were prepared by sol–gel processing followed by supercritical drying or aging in the mother solution at 100 °C. After drying and calcination, the catalyst supports were impregnated with a copper(II) nitrate aqueous solution by the incipient wetness method to achieve a Cu loading of about 2%. The samples showed ∼90% NO conversion at 350–400 °C. The catalytic performance of these systems appears to be determined by the degree of clustering of copper cations as probed by FTIR spectroscopy of adsorbed CO.

Nanocomposite Catalysts for Steam Reforming of Methane and Biofuels: Design and Performance

Vladislav Sadykov, Natalia Mezentseva, Galina Alikina, Rimma Bunina, Vladimir Pelipenko, Anton Lukashevich, Zakhar Vostrikov, Vladimir Rogov, Tamara Krieger, Arkady Ishchenko, Vladimir Zaikovsky, Lyudmila Bobrova, Julian Ross, Oleg Smorygo, Alevtina Smirnova, Bert Rietveld and Frans van Berkel, 1Boreskov Institute of Catalysis, Novosibirsk State University, 2University of Limerick, 3Powder Metallurgy Institute, 4Eastern Connecticut State University, 5Energy Research Center of the Netherlands, 1Russia 2Ireland 3Belarus 4USA 5Netherlands

Performance of monolithic catalysts with complex active component in partial oxidation of methane into syngas: experimental studies and modeling

Publisher Summary Partial oxidation of methane (POM) on monolithic catalysts at short contact times is a promising process for designing compact syngas generators. As is demonstrated for Rh- or Pt- supported catalysts, the optimization of their performance requires process modeling based upon a detailed elementary step reaction mechanism verified for pure metals. For more complex active components such as Pt-promoted LaNiO 3 /Ce-Zr-O etc, elucidation of such detailed elementary kinetics would require too extensive research. This chapter presents a verification of more simple approach to modeling of both steady-state and start-up performance based upon using the rate constants for the reactions of methane selective oxidation and reforming reactions estimated for small separate units of monolithic catalysts in nearly isothermal conditions. Two types of honeycomb monolithic substrates based on corundum (a hexagonal prism with a side of 40 mm and triangular channels with wall thickness of 0.2–0.3 mm) or fechraloy foil (cylindrer 50 mm diameter, 200–400 cpsi, 20 μm foil thickness) were used. The metal surface is protected by a thin (∼10 μm) nonporous layer of corundum supported by the dust blasting. The active component comprised of mixed LaNiO 3 /Ce-Zr-La-O oxides (up to 15 wt%) and Pt (up to 0.5 wt.%) was supported via washcoating and/or impregnation procedures followed by drying and calcination.

Doped Nanocrystalline Pt-Promoted Ceria-Zirconia as Anode Catalysts for IT SOFC: Synthesis and Properties

Ceria-zirconia samples doped with Gd, Pr, Sm, or La cations were prepared via Pechini route and promoted by Pt. Effect of their real structure and surface properties (characterized by neutronography, EXAFS, XPS, FTIRS of adsorbed CO) on the mobility and reactivity of the lattice oxygen (by oxygen isotope exchange and CH 4 TPR) was analyzed. For the reaction of CH 4 steam reforming (SR), catalytic performance is determined both by Pt dispersion and lattice oxygen mobility. Ni-YSZ anodes promoted by these catalysts possess a stable and efficient performance in CH 4 SR in the 600-800°C range in stoichiometric feeds without coking.

Nanocomposites Based Upon Alumina and Zirconia Pillared Clays Loaded with Transition Metal Cations and Clusters of Precious Metals: Synthesis, Properties and Catalysis of NO x Selective Reduction by Hydrocarbons

Thermally stable alumina and zirconia pillared clays loaded with copper and cobalt cations and silver nanoparticles were synthesized. The structural and surface features of these nanosystems were studied and compared with those of bulk analogs -partially stabilized zirconias and γ-alumina loaded with the same active components. Specificity of the catalytic properties of nanocomposites in the reactions of nitrogen oxides reduction by propane, propylene and decane in the excess of oxygen appears to be determined both by the degree of interaction between pillars and active components and the type of reducing agent.

HYDROCARBON SPECIFICITY IN THE SELECTIVE CATALYTIC REDUCTION OF NOX OVER CU-ZSM-5 AND CO-ZSM-5 CATALYSTS

Transformation of surface nitrates under CH4 (CH4+O2) was found to ensure steady-state activity of Co-ZSM-5 in the selective catalytic reduction of nitrogen oxides by methane (CH4-SCR). For Cu-ZSM-5, such species are mainly converted into NO. Relaxation of the coordination sphere due to oxygen and NO adsorption, stability of C,N-containing intermediates and activation routes of hydrocarbons (methane, propane) were analyzed as factors determining catalytic properties of Cu and Co cations.