S. F. Tikhov

Honeycomb catalysts for clean-up of diesel exhausts based upon the anodic-spark oxidized aluminum foil

Abstract The technology of the aluminum foil anodic spark oxidation in the water-based electrolytes has been applied to form strongly adhering protective alumina layer at the surface. Basic features of the oxidation were studied by SEM and XRD. Secondary supports, promoters and modifiers including rare-earth elements were used to increase the thermal stability of these composites up to 900°C. These materials were assembled as thin wall honeycomb supports loaded with a number of active components. The catalysts were tested in the reactions of CO and CHx oxidation, NOx selective reduction by hydrocarbons and demonstrated a high performance and a low pressure drop at high space velocities. City diesel buses field tests of converters equipped with those catalysts demonstrated their high and stable performance in clean-up of exhausts from SOF, CO, gaseous hydrocarbons and NOx.

CrAl alloy-based cermet monolith with polymodal pore structure for partial oxidation of methane to synthesis gas

The main stages of the CrAl alloy-based monoliths preparation from the Al and Cr powders through mechanical alloying, hydrothernal treatment and calcination have been described. The textural, mechanical and catalytic properties in the partial oxidation of methane on the monolithic cermets are presented.

Monolith composite catalysts based on ceramometals for partial oxidation of hydrocarbons to synthesis gas

Microchannel ceramometal monoliths of a high thermal and mechanical stability have been synthesized via hydrothermal treatment of powdered mixtures containing aluminum and additives (oxides or/and Ni-Cr(Co) alloy) followed by calcination. The phase composition and textural properties of monoliths depend on the additive nature affecting the aluminum reactivity toward oxidation and the interaction of remaining Al0 as well. Microchannel ceramometal monoliths and catalysts based on them ensure a high performance and stability in CPO of hydrocarbons at short contact times.

Design of Some Oxide/Metal Composite Supports and Catalysts

Textural, mechanical and catalytic properties of porous composite materials Al2O3/Al, MeO x (Me)/Al2O3/Al with metal particles homogeneously distributed in the alumina matrix were studied. These materials were prepared by mixing the powdered components with aluminum followed by hydrothermal treatment and calcination. The macroporous structure was shown to be controlled by the size of large (>microns) particles in starting blends. The mesoporous structure is primarily determined by the properties of alumina formed by dehydration of hydroxide produced in turn via aluminum oxidation by water. The mechanical strength of porous cermets is determined by the number and properties of contacts between micron-size components of composites. Improved catalytic performance of composites is ensured by the developed macroporous structure providing enhanced mass transfer inside the cermet granules.

Synthesis gas production from bio-oil: steam reforming of ethanol as a model compound

Using original hydrothermal technology honeycomb corundum monoliths with a peculiar porous structure and high water-adsorbing capacity facilitating procedures of active component loading have been produced. The detailed study of ethanol steam reforming over Ru/Ce0.5Zr0.5O2(CZ), Ru/Ce0.4Zr0.4Sm0.2O2–(δ + γ)Al2O3 (granulated) and Ru/Ce0.4Zr0.4Sm0.2O2/α-Al2O3 (monolithic) has been performed. It has been revealed that the main route of the reaction over Ru/CZ is ethanol dehydrogenation while ethanol dehydration into ethylene mainly occurs over Ru/CZS–Al2O3. Variation of the H2O–EtOH ratio, contact time and temperature allows hydrogen and CO yield to be governed. The monolithic catalyst has shown a high performance and stability at short contact time (0.1–0.4 s) and low water concentration (H2O–EtOH ∼ 1–3).

Hydrogenated Zr-Fe alloys encapsulated in Al2O3/Al matrix as catalysts for Fischer-Tropsch synthesis

Abstract The genesis of the ZrFe intermetallides with different atomic ratios during preparation of Zr y Fe z H y /Al 2 O 3 /Al catalysts and their performance in Fischer-Tropsch synthesis has been studied. The effect of structural, surface and textural properties on their activity had have been discussed.

Formation of Intermetallic Phases during Mechanical Alloying and Annealing of Cr + 20 wt % Al Mixtures

We have studied phase-formation processes in mixtures of Cr and Al (20 wt %) powders in the course of mechanical alloying (MA) and the phase transformations of the samples during subsequent annealing at temperatures of up to 800°C. The resultant x-ray amorphous intermetallic phases were identified by a differential dissolution method, which allows one to follow the formation of x-ray amorphous and partially crystallized phases. During MA of Cr + Al mixtures, the first to form is x-ray amorphous Cr4Al, which then converts to partially crystallized Cr2Al through reaction with aluminum. The peritectoid decomposition of Cr4Al during heating of the MA samples is accompanied by heat release at 330–350°C. Heating to 420°C leads to the formation of Cr5Al8. At 800°C, Cr5Al8 reacts with Cr to form Cr2Al.

Catalytic combustion: Achievements and problems

A catalytic method of combustion of a solid fuel in a fluidized bed is compared with a noncatalytic method. It is shown that the use of catalysts reduces the fuel consumption and sizes of heat generators approximately by an order of magnitude, while the specific load on the reactor volume increases by more than a factor of 20. Emission of toxic substances with fuel combustion products drastically decreases. Comparative stability of oxide non-platinum catalysts is estimated in the course of catalytic burning of the fuel with addition of an inert material. In burning fuels with a large content of sulphur, the maximum deactivation is found to occur within the first several tens of hours; this process is accompanied by sulphur accumulation in catalysts. Later on, the catalyst activity remains almost unchanged. It is found that a critical factor of catalyst stability is attrition resistance. The prospects of fuel burning in a layer of cermet honeycomb catalysts are demonstrated.

Catalytic combustion of brown coal particulates over ceramometal honeycomb catalyst

Abstract Catalytic combustion of brown coal particulates over CuO/Al2O3/FeAlO/ FeAl honeycomb ceramometal catalyst in the fluidized bed regime with the sand as a heat transfer material has been studied during 100 hours at 973-1023 K. The catalyst before and after tests has been analyzed. The coal conversion in the presence of cermet catalyst was found to be in the range of 97.8-98.5% while without catalyst it was lower (91.2-94.6%). A substantial decrease of CO, NOx and SO2 emissions in catalytic combustion was also demonstrated.

Zrfe intermetallides for fischer-tropsch synthesis : Pure and encapsulated into alumina-containing matrices

Abstract Performance of the bulk hydrogenated ZrFe intermetallides both pure and encapsulated into alumina-containing matrix (Al 2 O 3 /Al, Al 2 O 3 ) was studied in catalysis of Fischer-Tropsch synthesis. Their structural, textural and surface properties were characterized by combination of such methods as XRD, SEM, TEM, nitrogen adsorption-desorption isotherms and XPS, and impact of these properties on catalytic activity and selectivity was analyzed. The highest activity per the surface Fe atom (~5·10 −19 CH x /at. Fe ·h) was obtained for pure active component, while the highest activity per the unit of volume (~168 g C 5 +/l · h) was revealed for a composite catalyst at 300°C, 3 MPa and space velocity ~7000 h −1 .