Исследование катализаторов на основе твердого раствора Ce0.72Zr0.18Pr0.1O2 c нанесенными Pt, Pd и Ru из ацетилацетонатных прекурсоров показало их высокую активность в процессах окисления CO и метана. Для установления природы активных центров катализаторов применялись методы: просвечивающей электронной микроскопии, рентгеновской абсорбционной спектроскопии и рентгеновской фотоэлектронной спектроскопии. Обнаружен эффект взаимодействия металлноситель, усиливающийся в ряду Ru < Pd < Pt, и установлена взаимосвязь между интенсивностью такого взаимодействия и каталитическим действием.
There were synthesized catalysts based on high-porous cellular materials by means of d- and f-elements oxides' impregnation. There were inves-tigated their textural characteristics and catalytic activity in oxidative reactions in gas and liquid phase. Received catalysts will be prospective for treatment of gas emissions and wastewater of industrial enterprises.
The solid solutions M0,1Zr0,18Ce0,72O2, where M is a rare earth metal (REM) are synthesized. The structural and textural characteristics of prepared compositions were studied by XRD, Raman spectroscopy, TEM and low-temperature nitrogen adsorption. It is shown that the introduction of 10 mol.% REM in the solid solution Zr0,2Ce0,8O2 allows to save the cubic fluorite structure. In this case the parameter of lattice of solid solution decreases with increasing the atomic number of REM. The synthesized samples are nanosized: the ceria crystallite size is 13,3 nm, Zr0,2Ce0,8O2 – 11,2 nm, M0,1Zr0,18Ce0,72O2 – about 8 nm. According to TEM, the average particle size is 15 nm. The incorporation of REM increases the specific surface area and porosity due to the formation of more defective structure. There is determination of the catalytic activity of the synthesized solid solutions in CO oxidation in a flow reactor under the conditions: pressure 0,1 MPa, temperature of 20–500 °C, space velocity of 1800 h–1 gas mixture (vol.%): CO – 3,6; O2 – 8,0; N2 – balance. The samples with light REM (praseodymium, samarium, neodymium) were the most active, they have a high oxygen storage capacity (OSC). That new catalysts have an interest for the purification processes from gas emissions of motor vehicles.
Nanoparticulate catalysts M/Ce0,72Zr0,18Pr0,1O2, where M – Pt, Pd, Ru at 0,5; 1,0 and 2,0 wt.%, for diesel exhaust soot afterburning in a «weak» contact were synthesized. Structural, textural and catalytic properties of the samples were studied using EDX, X-ray synchrotron diffraction, XANES, EXAFS, TEM, low-temperature nitrogen adsorption and TG-DSC. It is shown that in the process of impregnating of platinum metals on the surface of the support Ce0,72Zr0,18Pr0,1O2, metal-support interaction occurs and increases in a line Pt → Pd → Ru. Ruthenium-ontaining catalysts are the most active in the soot afterburning, not only due to the nature of the supported component, but relatively faint metal-support interaction as compared with platinum and palladium samples. For them it is characterized the reduction of start oxidation temperature on 190 °C and lowering the temperature of complete oxidation approximately on 120 °C compared with the same parameters for the support without platinum. Due to the high activity of 0,5%Ru/Ce0,72Zr0,18Pr0,1O2 the opportunity for effective cleaning of diesel soot emissions are created by using relatively small amounts of the precious metal, which will reduce the cost of catalytic converters of diesel emissions.
There are synthesized nanostructured solid solutions of Me-Zr-Ce-O (Me = Sc, Y, La, Pr, Nd, Sm) based on the cubic fluorite lattice of ceria. By the methods of X-ray fluorescence analysis, BET and gas chromatography, there are studied structural and catalytic properties of the samples. The catalysts have high catalytic activity and thermal stability, which indicates the possibility of their use in the process of detoxification of gaseous media from carbon monoxide.
